Astm mnl 1 2010

The sulfur content of spark-ignition engine fuel can be determined by the following methods: • ASTM D1266/IP 107, Test Method for Sulfur in Petro-leum Products Lamp Method • ASTM D2622,

Dr Salvatore J Rand is an independent consultant to the

petroleum industry, and a Fellow of ASTM International

He was awarded the baccalaureate degree in Chemistry

and Philosophy from Fordham University and a doctorate

in Physical Chemistry and Physics from Rensselaer

Polytechnic Institute He retired from the Texaco Research

Center following twenty-seven years of service During

that time he managed the Fuels Test Laboratory, and

provided technical information and services to company

facilities worldwide regarding fuel distribution, marketing

and operations, laboratory inspection and auditing, and

training of personnel both in proprietary and commercial

laboratories He also represented Texaco on various ASTM

D02 subcommittees His achievements include developing

company-wide quality control programs for the distribution

of fuels throughout the entire United States.

He has developed and conducts the ASTM training courses

Salvatore J Rand, Ph.D.

www.astm.org ISBN: 978-0-8031-7001-8

Stock #: MNL1-8TH

“Gasoline: Specifi cations, Testing and Technology” and

“Fuels Technology” and has taught these courses almost one hundred times throughout the world He previously held the position of Second Vice-Chairman of ASTM

Committee D02, Petroleum Products and Lubricants He was also Chairman of Subcommittee D02.05, Properties

of Fuels, Petroleum Coke and Carbon Material, Secretary

of Subcommittee D02.05.0C, Color and Reactivity, and a member of ASTM’s Committee on Technical Committee Operations (COTCO) He is the author of a number of publications in the scientifi c literature, is a fi ft y year member

of the American Chemical Society, and is a past Chairman

of its Mid-Hudson Section He is the recipient of numerous awards, including ASTM’s highest award, the Award of

Merit, D02’s highest award, the Scroll of Achievement, the George K Dyroff Award of Honorary D02 Membership,

and the Lowrie B Sargent Award.

Significance of Tests for Petroleum Products

8th Edition

Salvatore J Rand, Editor

ASTM Stock Number MNL1-8TH

Copyright 2009 by ASTM International www.astm.org

Library of Congress Cataloging-in-Publication Data

Significance of tests for petroleum products — 8th ed / [edited by] Salvatore J Rand

repro-Photocopy RightsAuthorization to photocopy items for internal, personal, or educational classroom use of specific clients is granted byASTM International provided that the appropriate fee is paid to ASTM International, 100 Barr Harbor Drive, PO BoxC700 West Conshohocken, PA 19428-2959, Tel: 610-832-9634; online: http://www.astm.org/copyright/

ASTM International is not responsible, as a body, for the statements and opinions advanced in the publication ASTMdoes not endorse any products represented in this publication

Printed in Newburyport, MA,ii

May, 2010

THIS PUBLICATION, Significance of Tests for Petroleum Products: 8th Edition, was sponsored by ASTM committee D02 on Petroleum Products and Lubricants The editor is Salvatore J Rand, Consultant, North Fort Myers, Florida This is the 8thedition of Manual 1 in the ASTM International manual series.

iii

To Mary, Cathy, Jeanne, Joseph, and Johniv

This manual was brought to fruition by the combined efforts of many individuals I would like to convey

my sincerest appreciation to all of them, particularly the publication staff of ASTM International, cially Kathy Dernoga and Monica Siperko, who have given us much behind-the-scenes guidance and assis- tance from the outset of this venture I also wish to thank Christine Urso of the American Institute of Physics, who was responsible for this logistically challenging project of handling the 24 chapters and 37 authors involved in this publication In addition, I wish to convey my accolades to the authors, who are all experts in their particular fields and who bring a broad spectrum of topics and interests to this manual They have devoted considerable time, energy, and resources to support this endeavor I am also grateful to the 46 experts who reviewed the various chapters, who through their perusal of the chapters and their sug- gestions permitted good manuscripts to be made better Finally, I would like to extend my appreciation to the industrial and governmental employers of all those involved in this publication They ultimately make

espe-it possible for us to produce manuals such as this for the benefespe-it of those who use petroleum standards worldwide.

v

Chapter 1—Introduction 1

by Salvatore J RandChapter 2—Automotive Spark-Ignition Engine Fuel 3

by Lewis M Gibbs, Ben R Bonazza, and Robert L FureyChapter 3—Fuel Oxygenates 16

by Marilyn J Herman and Lewis M GibbsChapter 4—Fuels for Land and Marine Diesel Engines and for Nonaviation Gas Turbines 33

by Steven R Westbrook and Richard T LeCrenChapter 5—Biodiesel 53

by Steve HowellChapter 6—Burner, Heating, and Lighting Fuels 65

by C J Martin and Lindsey HicksChapter 7—Aviation Fuels 80

by John RhodeChapter 8—Crude Oils 106

by Harry N GilesChapter 9—Properties of Petroleum Coke, Pitch, and Manufactured Carbon and Graphite 123

by C O Mills and F A IannuzziChapter 10—Sampling Techniques 136

by Peter W Kosewicz, Del J Major, and Dan ComstockChapter 11—Methods for Assessing Stability and Cleanliness of Liquid Fuels 151

by David R Forester and Harry N GilesChapter 12—Gaseous Fuels and Light Hydrocarbons [Methane through Butanes, Natural Gasoline,

and Light Olefins] 164

by Andy PickardChapter 13—Petroleum Solvents 173

by R G MontemayorChapter 14—White Mineral Oils 184

by C Monroe CopelandChapter 15—Lubricant Base Oils 189

by Jennifer D HallChapter 16—Lubricating Oils 197

by Dave WillsChapter 17—Passenger Car Engine Oil and Performance Testing 210

by Raj Shah and Theodore SelbyChapter 18—Petroleum Oils for Rubber 224

by John M Long and John H BachmannChapter 19—Lubricating Greases 229

by Raj ShahChapter 20—Petroleum Waxes Including Petrolatums 252

by Alan R CaseChapter 21—Methods for the Environmental Testing of Petroleum Products 261

by Mark L HinmanChapter 22—Determination of Inorganic Species in Petroleum Products and Lubricants 283

by R A Kishore NadkarniChapter 23—Standard Test Method Data Quality Assurance 299

by Alex T C LauChapter 24—Synthetic Liquid Fuels 304

by Lelani Collier, Carl Viljoen, Mirriam Ajam, Mazwi Ndlovu, Debby Yoell,Paul Gravett, and Nico Esterhuyse

Index 316

vii

Dr Salvatore J Rand is an independent consultant to the

petroleum industry, and a Fellow of ASTM International

He was awarded the baccalaureate degree in Chemistry

and Philosophy from Fordham University and a doctorate

in Physical Chemistry and Physics from Rensselaer

Polytechnic Institute He retired from the Texaco Research

Center following twenty-seven years of service During

that time he managed the Fuels Test Laboratory, and

provided technical information and services to company

facilities worldwide regarding fuel distribution, marketing

and operations, laboratory inspection and auditing, and

training of personnel both in proprietary and commercial

laboratories He also represented Texaco on various ASTM

D02 subcommittees His achievements include developing

company-wide quality control programs for the distribution

of fuels throughout the entire United States.

He has developed and conducts the ASTM training courses

Salvatore J Rand, Ph.D.

www.astm.org ISBN: 978-0-8031-7001-8 Stock #: MNL1-8TH

“Gasoline: Specifi cations, Testing and Technology” and

“Fuels Technology” and has taught these courses almost one hundred times throughout the world He previously held the position of Second Vice-Chairman of ASTM Committee D02, Petroleum Products and Lubricants He was also Chairman of Subcommittee D02.05, Properties

of Fuels, Petroleum Coke and Carbon Material, Secretary

of Subcommittee D02.05.0C, Color and Reactivity, and a member of ASTM’s Committee on Technical Committee Operations (COTCO) He is the author of a number of publications in the scientifi c literature, is a fi ft y year member

of the American Chemical Society, and is a past Chairman

of its Mid-Hudson Section He is the recipient of numerous awards, including ASTM’s highest award, the Award of Merit, D02’s highest award, the Scroll of Achievement, the George K Dyroff Award of Honorary D02 Membership, and the Lowrie B Sargent Award.

Introduction

Salvatore J Rand1

change No longer do people have to wait months or even

years for analytical methods to be submitted to ASTM

Inter-national, tested, and voted for approval The response of the

various committees of ASTM International to new

develop-ments in the industrial and petroleum industries, and to

unexpected occurrences in the field, is both swift and

focused It is because of this unprecedented and exponential

increase in new testing methods that Manual 1 is being

revised only 6 years after its prior publication

Committee D02 on Petroleum Products and Lubricants

has assumed the responsibility of revisingManual on

Signifi-cance of Tests for Petroleum Products (ASTM Manual Series:

MNL 1), although other national and international standards

organizations contribute significantly to the development of

standard test methods for petroleum products These

organi-zations include the Energy Institute (EI), formerly known

as the Institute of Petroleum in the United Kingdom, the

Deutsches Institut fu¨r Normung (DIN) in Germany, the

Asso-ciation Française de Normalisation (AFNOR) in France, the

Japanese Industrial Standards (JIS) in Japan, the CEN

(Euro-pean Committee for Standardization), and the International

Organization for Standardization (ISO) Selected test

meth-ods from these organizations have been cross-referenced

where relevant with ASTM International standards in selected

chapters in this publication There are discussions presently

in progress to harmonize many standard test methods so they

are technically equivalent to one another

The chapters in this manual are not intended to be

research papers or exhaustive treatises of a particular field

The purpose of the discussions herein is to answer two

ques-tions: What are the relevant tests that are done on various

petroleum products and why do we perform these particular

tests? All tests are designed to measure properties of a

prod-uct such that the “quality” of that prodprod-uct may be described

I consider a workable definition of a quality product to be

“that which meets agreed-on specifications.” It is not

neces-sary that the quality of a product be judged by its high

purity, although it may very well be, but merely that it meets

specifications previously agreed on among buyers, sellers,

regulators, transferors, etc The various chapters in this

pub-lication discuss individual or classes of petroleum products

and describe the standardized testing that must be done on

those products to assure all parties involved that they are

dealing with quality products

Since publication of the previous edition of the manual,

not only has the number available but also the type of some

petroleum products undergone dramatic changes The result

is that most products have had changes incorporated into

their methods of test, and that these new procedures havebeen standardized and accepted into specifications as required.The generic petroleum products discussed in this eighth edi-tion of Manual 1 are similar to those products described inthe chapters of the previous edition All chapters with oneexception have been updated to reflect new specification andtesting standards, where applicable Chapter 21, “Methods forthe Environmental Testing of Petroleum Products,” has beenreprinted in its entirety from the previous edition becausethe test procedures and protocols have been essentiallyunchanged and the discussion of toxicity and biodegradation

of petroleum products is relevant to today’s products In thediscussion of some of the various petroleum products,selected sections of chapters have been retained from theseventh edition for the sake of completeness and to providemore complete background information The authors of thechapters in the seventh edition have been credited in thefootnotes to the appropriate chapters where necessary.This edition has been enlarged by the inclusion of threenew chapters to more fully reflect today’s new products andnew testing procedures, while the original 21 chapters con-tained in the seventh edition have been retained andupdated One new chapter, “Biodiesel,” has been added inresponse to the worldwide interest in developing renewablefuels In addition to oxygenates, which are generally blendedfor gasoline engines, specifications for diesel fuel are beingchanged to incorporate materials of biological origin for thepurpose of sustainability of fuels products Government regu-lators are mandating the use of biodiesel fuels (“biodiesels”)and are presently in discussions with petroleum companiesand engine manufacturers to ensure conformance with pub-lished timetables for the use of these fuels Committee D02has responded with the development of specifications andnew test methods, as described in this new chapter

Another new chapter is entitled “Synthetic Liquid Fuels.”Again, due to the worldwide interest in diminishing depen-dence on traditional petroleum fuels, research in alternativefuels is being conducted by many organizations includingpetroleum companies Specifications and test methods forsynthetic fuels are continually being developed by CommitteeD02 to define the characteristics of these new materials, andthese are discussed in the new chapter

The various petroleum products, including crude oils,have always been tested to determine the qualitative andquantitative nature of inorganic substances contained therein.This is discussed in the new chapter “Determination ofInorganic Species in Petroleum Products and Lubricants.”The techniques used are many and varied, the product andthe nature and concentration of the inorganic species In

1 Consultant, North Fort Myers, FL.

1

Copyright © 2010 by ASTM International www.astm.org

addition, a number of unexpected problems have recently

arisen in the field regarding inorganic materials affecting the

performance of petroleum fuels One such problem is the

deposition of silicon dioxide on gasoline engine parts due to

the contamination of gasoline with very small quantities of

silicon Another problem is the inactivation of silver alloy–

sensing units in fuel tanks with the use of some low-sulfur

gasoline fuels Still another concern is the deposition of

sulfate-containing materials in fuel metering systems and on

fuel dispenser filters when certain ethanol batches are

blended with gasoline These problems require methods that

measure inorganic contaminants at extremely low levels using

new techniques, all of which are under development in

Com-mittee D02

Many of the test procedures described in this manual are

newer correlative methods, which represent the way of the

future due to their simplicity, objectivity, economy, and, inmany cases, portability Quality assurance methods must beintegrated into analytical procedures and protocols, so that wecan demonstrate that these methods provide accuracy and pre-cision equal to or better than the referee methods they super-sede A major thrust in analytical chemistry at the present isthe development of methods that count individual molecules.While we have not yet achieved this level of sensitivity in thetesting of petroleum products, when these new tools do arrive,and they will, we will be able to determine the concentration

of an analyte in a petroleum product with 100% accuracy.The chapters that follow show that the technology asso-ciated with the testing of petroleum products is advancing at

an increasingly rapid rate They also demonstrate that ASTMInternational continues to be the foremost standardizationorganization in the world

Automotive Spark-Ignition Engine Fuel

Lewis M Gibbs,1Ben R Bonazza,2 and Robert L Furey3

consists of gasoline or gasoline-oxygenate blends used in

internal combustion spark-ignition engines, as opposed to

engine fuels used in diesel or compression-ignition engines

These spark-ignition engine fuels are used primarily in

pas-senger car and highway truck service They are also used in

off-highway utility trucks, farm machinery, two- and

four-stroke cycle marine engines, and other spark-ignition engines

used in a variety of service applications

ASTM D4814, Specification for Automotive

Spark-Ignition Engine Fuel, definesgasoline as a volatile mixture of

liquid hydrocarbons, containing small amounts of additives

Agasoline-oxygenate blend is defined as a fuel consisting

pri-marily of gasoline, along with a substantial amount of one or

more oxygenates Anoxygenate is an oxygen-containing,

ash-less organic compound, such as an alcohol or ether, which

can be used as a fuel or fuel supplement Ethanol is the

pre-dominant oxygenate in use today Spark-ignition engine fuel

includes both gasolines and gasoline-oxygenate blends

Gasoline is a complex mixture of relatively volatile

hydrocar-bons that vary widely in their physical and chemical properties

It is a blend of many hydrocarbons derived from the fractional

distillation of crude petroleum and from complex refinery

proc-esses that increase either the amount or the quality of gasoline

The hundreds of individual hydrocarbons in gasoline

typ-ically range from those having just four carbon atoms

(desig-nated C4, composed of butanes and butenes) to those having

as many as 11 carbon atoms (designated C11, such as

methyl-naphthalene) The types of hydrocarbons in gasoline are

par-affins, isoparpar-affins, naphthenes, olefins, and aromatics The

properties of commercial gasolines are predominantly

influ-enced by the refinery practices that are used and partially

influenced by the nature of the crude oils from which they

are produced Finished gasolines have a boiling range from

about 30 to 225
C (86 to 437
F) in a standard distillation test

Gasoline may be blended, or may be required to be

blended, with oxygenates to improve the octane rating, extend

the fuel supply, reduce vehicle exhaust emissions, or comply

with regulatory requirements The oxygenated components of

spark-ignition engine fuel include aliphatic ethers, such as

methyltert-butyl ether (MTBE), and alcohols such as ethanol

The ethers are allowed by U.S Environmental Protection

Agency (EPA) regulations to be used in concentrations where

they provide not more than 2.7 mass percent oxygen in the final

fuel blend Because of concerns over ground water

contamina-tion, MTBE is banned in many states and is no longer widely

used in the United States Ethanol and certain other alcohols

may provide not more than 3.7 mass percent oxygen in the fuel

Legal restrictions exist on the use of methanol in gasoline, and

it is not currently intentionally added to any gasolines marketed

in the United States These restrictions will be discussed later.The federal Renewable Fuel Standard (RFS) established underthe Energy Independence and Security Act of 2007 requires anational minimum volume usage requirement of ethanol thatincreases annually until 2022 In addition, a number of states orportions of states mandate that spark-ignition engine fuel con-tain 10 volume percent ethanol blended with gasoline

Spark-ignition engine fuels are blended to satisfy diverseautomotive requirements In addition, the fuels are exposed

to a variety of mechanical, physical, and chemical ments Therefore, the properties of the fuel must be bal-anced to give satisfactory engine performance over anextremely wide range of operating conditions The prevailingstandards for fuel represent compromises among the numer-ous quality, environmental, and performance requirements.Antiknock rating, distillation characteristics, vapor pressure,sulfur content, oxidation stability, corrosion protection, andother properties are balanced to provide satisfactory vehicleperformance In most gasolines, additives are used to pro-vide or enhance specific performance features

environ-In recent years, there has been an ever-growing body of ernmental regulations to address concerns about the environ-ment Initially, most of the regulations were aimed at theautomobile and have resulted in technologies that have signifi-cantly reduced vehicle emissions Regulations have also beenaimed at compositional changes to the fuels that result inreduced vehicle emissions The first major change in fuel compo-sition was the introduction of unleaded gasoline in the early1970s, followed by the phase-down of lead levels in leaded gaso-line (1979–1986) Most passenger cars and light-duty trucksbeginning with the 1975 model year have required unleaded fuel

gov-In 1989, the U.S EPA implemented gasoline volatilityregulations Reductions in fuel vapor pressure limits duringthe summer were implemented under these regulations, fol-lowed by further reductions in 1992

Beginning in 1987, several states required the addition

of oxygenates to gasoline during the winter months in tain geographic areas to reduce vehicle carbon monoxideemissions The added oxygenates are especially effective inreducing carbon monoxide during a cold start with oldervehicles When a vehicle is started cold, the catalyst is inac-tive and the computer is not controlling the air-fuel ratio inclosed-loop mode Added oxygen in the fuel leans thevehicle’s fuel mixture, lowering carbon monoxide emissions.The Clean Air Act Amendments of 1990 required addi-tional compositional changes to automotive spark-ignition

cer-1

Chevron Products Company, Richmond, CA.

2 TI Automotive (retired), Lapeer, MI.

3 Furey & Associates, LLC, Rochester Hills, MI.

3

Copyright © 2010 by ASTM International www.astm.org

engine fuels In November 1992, 39 areas failing to meet the

federal standard for carbon monoxide were required to

implement oxygenated fuel programs similar to those

men-tioned previously There are also provisions in the act that

address ozone nonattainment Beginning in 1995, the use of

a cleaner-burning “reformulated gasoline” was required in

the nine worst ozone nonattainment areas Other ozone

non-attainment areas have the option of participating in the

pro-gram Federal reformulated gasoline is a gasoline-oxygenate

blend certified to meet the specifications and emission

reduction requirements established by the Clean Air Act

Amendments of 1990; therefore, it would be more correctly

referred to as federal reformulated spark-ignition engine

fuel Federal and state regulations frequently use the term

“gasoline” to cover both gasoline and gasoline-oxygenate

blends (See ASTM Committee D02 on Petroleum Products

and Lubricants Research Report D02: 1347, Research

Report on Reformulated Spark-Ignition Engine Fuel for

reformulated gasoline requirements and test methods.)

This chapter summarizes the significance of the more

important physical and chemical characteristics of

automo-tive spark-ignition engine fuel and describes pertinent test

methods for defining or evaluating these properties

Infor-mation on governmental requirements is also provided This

discussion applies only to those fuels that can be used in

engines designed for spark-ignition engine fuel It does not

include fuels that are primarily oxygenates, such as M85, a

blend of 85 volume percent methanol and 15 volume

per-cent gasoline, or E85, a blend of 85 volume perper-cent ethanol

and 15 volume percent gasoline, which are for use in

flexi-ble fuel vehicles These fuels and the oxygenates commonly

used in gasoline are discussed in detail in Chapter 3 [See

ASTM D5797, Specification for Fuel Methanol (M70-M85) for

Automotive Spark-Ignition Engines, or ASTM D5798,

Specifi-cation for Fuel Ethanol (Ed75-Ed85) for Automotive

Spark-Ignition Engines.]

GRADES OF SPARK-IGNITION ENGINE FUEL

Until 1970, with the exception of one brand of

premium-grade fuel marketed on the East Coast and southern areas

of the United States, all grades of automotive fuel contained

lead alkyl compounds to increase the antiknock rating The

Antiknock Index [the average of the Research Octane

Num-ber (RON) and the Motor Octane NumNum-ber (MON)] of the

leaded premium-grade fuel pool increased steadily from

about 82 at the end of World War II to about 96 in 1968

During the same time, the Antiknock Index of the leaded

regular grade followed a parallel trend from about 77 to 90

Leaded fuel began to be phased out during the 1970s, and

in 1996 all lead was banned from highway fuel

In 1971, U.S passenger car manufacturers began a

tran-sition to engines that would operate satisfactorily on fuels

with lower octane ratings, namely, a minimum RON of 91

This octane level was chosen because unleaded fuels are

needed to prolong the effectiveness of automotive emission

catalyst systems and because unleaded fuels of 91 RON could

be produced in the required quantities using refinery

process-ing equipment then available In 1970, fuel marketers

intro-duced unleaded and low-lead fuels of this octane level to

supplement the conventional leaded fuels already available

Beginning in July 1974, the U.S EPA mandated that

most service stations have available a grade of unleaded fuel

defined as having a lead content not exceeding 0.013 gram of

lead/liter (g Pb/L) [0.05 gram of lead/U.S gallon (0.05 g Pb/gal)] and a RON of at least 91 (This was changed to a mini-mum Antiknock Index of 87 in 1983, and the requirementwas dropped in 1991.) Starting in the 1975 model year, mostspark-ignition engine–powered automobiles and light-dutytrucks required the use of unleaded fuel With this require-ment, low-lead fuels [0.13 g Pb/L (0.5 g Pb/gal)] disappeared

In addition, leaded premium began to be superseded byunleaded premium in the late 1970s and early 1980s In themid-1980s, an unleaded midgrade fuel became widely avail-able, and many fuel marketers now offer three grades ofunleaded fuel: regular, midgrade, and premium Lead usage

in motor fuels was banned entirely in California effective in

1992 and was banned from all U.S reformulated fuels in

1995 and from all U.S motor fuels in 1996 Leaded fuel canstill be produced for off-road use and for use as a racing fuel.ANTIKNOCK RATING

The definitions and test methods for antiknock rating forautomotive spark-ignition engine fuels are set forth in Appen-dix X1 in ASTM D4814, Specification for Automotive Spark-Ignition Engine Fuel Antiknock rating and volatility are per-haps the two most important characteristics of spark-ignitionengine fuel If the antiknock rating of the fuel is lower thanthat required by the engine, knock occurs Knock is a high-pitch, metallic rapping noise Fuel with an antiknock ratinghigher than that required for knock-free operation generallydoes not improve performance However, vehicles equippedwith knock sensors may show a performance improvement

as the antiknock rating of the fuel is increased, provided thatthe antiknock rating of the fuel is lower than that required

by the engine Conversely, reductions in fuel antiknock ing may cause a loss in vehicle performance The loss ofpower and the damage to an automotive engine due toknocking are generally not significant until the knock inten-sity becomes severe and prolonged

rat-Knock depends on complex physical and chemical nomena highly interrelated with engine design and operat-ing conditions It has not been possible to characterizecompletely the antiknock performance of spark-ignitionengine fuel with any single measurement The antiknock per-formance of a fuel is related intimately to the engine inwhich it is used and the engine operating conditions Fur-thermore, this relationship varies from one engine design toanother and may even be different among engines of thesame design, due to normal production variations

phe-The antiknock rating of a spark-ignition engine fuel ismeasured in single-cylinder laboratory engines Two methodshave been standardized and are presented in ASTM D2699/

IP 237, Test Method for Research Octane Number of Ignition Engine Fuel, and ASTM D2700/IP 236, Test Methodfor Motor Octane Number of Spark-Ignition Engine Fuel.Another method used for quality control in fuel blending isgiven in ASTM D2885/IP 360, Test Method for Research andMotor Method Octane Ratings Using On-Line Analyzers.These single-cylinder engine test procedures use a variable-compression-ratio engine The Motor method operates at ahigher speed and inlet mixture temperature than the Researchmethod The procedures relate the knocking characteristics of

Spark-a test fuel to stSpark-andSpark-ard fuels, which Spark-are blends of two purehydrocarbons: 2,2,4-trimethylpentane (“isooctane”) andn-heptane These blends are called primary reference fuels Bydefinition, the octane number of isooctane is 100, and the

octane number ofn-heptane is 0 At octane levels below 100,

the octane number of a given fuel is the percentage by volume

of isooctane in a blend withn-heptane that knocks with the

same intensity at the same compression ratio as the fuel when

compared by one of the standardized engine test methods The

octane number of a fuel greater than 100 is based on the

vol-ume of tetraethyl lead that must be added to isooctane to

pro-duce knock with the same intensity as the fuel The volume of

tetraethyl lead in isooctane is converted to octane numbers

greater than 100 by use of tables included in the Research and

Motor methods

The octane number of a given blend of either isooctane

andn-heptane or tetraethyl lead in isooctane is, by definition,

the same for the Research and Motor methods However, the

RON and MON will rarely be the same for commercial fuels

Therefore, when considering the octane number of a given

fuel, it is necessary to know the engine test method RON

is, in general, the better indicator of antiknock rating for

engines operating at full throttle and low engine speed MON

is the better indicator at full throttle, high engine speed, and

part throttle, low and high engine speed The difference

between RON and MON is called “sensitivity.” According to

recent surveys of U.S commercial fuels, the average

sensitiv-ity is about 9 units for unleaded regular grade and about 10

units for unleaded premium grade

For most automotive engines and operating conditions,

the antiknock performance of a fuel will be between its RON

and MON The exact relationship is dependent on the vehicle

and operating conditions Antiknock Index [the average of

RON and MON, that is, (Rþ M)/2] is a currently accepted

method of relating RON and MON to actual road antiknock

performance in vehicles U.S Federal Trade Commission

(FTC) regulations require a label on each service station

dis-pensing pump showing the minimum (Rþ M)/2 value of the

fuel dispensed For fuels sold in the United States, regular

grade is typically 87 (Rþ M)/2 (often slightly lower at high

alti-tudes), midgrade is typically about 89, and premium is

typi-cally 91 or higher Other grades also exist The terms used to

describe the various grades (e.g., regular, midgrade, super,

pre-mium, etc.) vary among fuel marketers and location With the

FTC regulation, a consumer can match the (Rþ M)/2 value

specified in the owner’s manual with the value on the pump

Because octane quality is a marketing issue, ASTM does not

specify a minimum Antiknock Index in ASTM D4814

VOLATILITY

The volatility characteristics of a spark-ignition engine fuel

are of prime importance to the driveability of vehicles under

all conditions encountered in normal service The large

var-iations in operating conditions and wide ranges of

atmos-pheric temperatures and pressures impose many limitations

on a fuel if it is to give satisfactory vehicle performance

Fuels that vaporize too readily in pumps, fuel lines,

carburet-ors, or fuel injectors will cause decreased fuel flow to the

engine, resulting in hard starting, rough engine operation, or

stoppage (vapor lock) Under certain atmospheric

condi-tions, fuels that vaporize too readily can also cause ice

for-mation in the throat of a carburetor, resulting in rough idle

and stalling This problem occurs primarily in older cars

Conversely, fuels that do not vaporize readily enough may

cause hard starting and poor warm-up driveability and

accel-eration These low-volatility fuels may also cause an unequal

distribution of fuel to the individual cylinders

The volatility of automotive spark-ignition engine fuelmust be carefully “balanced” to provide the optimum com-promise among performance features that depend on thevaporization behavior Superior performance in one respectmay give serious trouble in another Therefore, volatilitycharacteristics of automotive fuel must be adjusted for sea-sonal variations in atmospheric temperatures and geographicvariations in altitude Four common volatility properties aredescribed later The effect of these volatility parameters onthe performance of the vehicle is also presented

Vapor PressureOne of the most common measures of fuel volatility is thevapor pressure at 37.8
C (100
F) measured in a chamberhaving a 4:1 ratio of air to liquid fuel ASTM D323, TestMethod for Vapor Pressure of Petroleum Products (ReidMethod), can be used for hydrocarbon-only gasolines andgasoline-ether blends but not for gasoline-alcohol blendsbecause traces of water in the apparatus can extract thealcohol from the blend and lead to incorrect results There-fore, this method is no longer listed as an acceptable testmethod for spark-ignition engine fuels in ASTM D4814

To avoid the alcohol–water interaction problem in TestMethod D323, a similar method using the same apparatusand procedure, but maintaining dry conditions, has beendeveloped—ASTM D4953, Test Method for Vapor Pressure ofGasoline and Gasoline-Oxygenate Blends (Dry Method) Theresults are reported as Dry Vapor Pressure Equivalent(DVPE) rather than Reid Vapor Pressure (RVP), which is onlydetermined using Test Method D323 For hydrocarbon-onlygasolines, there is no statistically significant difference in theresults obtained by Test Methods D323 and D4953 Advances

in instrumentation have led to the development of threeother methods that can be used for both gasolines and gaso-line-oxygenate blends They are ASTM D5190, Test Methodfor Vapor Pressure of Petroleum Products (Automatic Method),ASTM D5191, Test Method for Vapor Pressure of PetroleumProducts (Mini Method), and ASTM D5482, Test Methodfor Vapor Pressure of Petroleum Products (Mini Method-Atmospheric) The precision (repeatability and reproducibil-ity) of these three methods is much better than that forD4953 Another method, ASTM D6378, Test Method forDetermination of Vapor Pressure (VPX) of Petroleum Prod-ucts, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures(Triple Expansion Method), is reported to not require air sat-uration and cooling of the sample before testing This testmethod reports results as VPX An equation is provided inthe test method to convert the results to DVPE to determinecompliance with Specification D4814 maximum limits.The U.S EPA and the California Air Resources Boarduse the D5191 test method However, each uses a slightly dif-ferent equation than that used by ASTM to calculate vaporpressure from the instrument’s total pressure reading Theequation used depends on the brand of the instrument.Distillation

The tendency of a fuel to vaporize is also characterized bydetermining a series of temperatures at which various per-centages of the fuel have evaporated, as described in ASTMD86, Test Method for Distillation of Petroleum Products atAtmospheric Pressure A plot of the results is commonlycalled the distillation curve The 10, 50, and 90 volume per-cent evaporated temperatures are often used to characterize

the volatility of spark-ignition engine fuel The fuel also can

be characterized by reporting the percentage evaporated at

specified temperatures (e.g., E100) Two gas chromatography

test methods that can be used to determine the distillation

characteristics are ASTM D3710, Test Method for Boiling

Range Distribution of Gasoline and Gasoline Fractions by

Gas Chromatography, and D7096, Test Method for

Determi-nation of the Boiling Range Distribution of Gasoline by

Wide-Bore Capillary Gas Chromatography Two distillation

test methods requiring considerably smaller sample sizes

than Test Method D86 are D7344, Test Method for

Distilla-tion of Petroleum Products at Atmospheric Pressure (Mini

Method), and D7345, Test Method for Distillation of

Petro-leum Products at Atmospheric Pressure (Micro Distillation

Method) To improve the correlation of reported results with

those of Test Method D86, bias corrections are provided

Driveability Index

While each area of the distillation curve is important, the

combination of the various points that describe the whole

curve must be taken into account to describe adequately

vehi-cle driveability The ASTM Driveability Task Force, using data

from the Coordinating Research Council (CRC) and others,

has developed a correlation between various distillation

points and vehicle cold-start and warm-up driveability This

correlation is called Driveability Index (DI) and is defined as:

DI¼ 1.5 3 T10 þ 3.0 3 T50 þ 1.0 3 T90 þ 1.33
C (2.4
F)

3 Ethanol Volume percent, where T10, T50, and T90 are the

temperatures at the 10, 50, and 90 % evaporated points of a

Test Method D86 distillation, respectively; 1.33 is the

coeffi-cient for the volume percent ethanol present when the

distil-lation results are determined in degrees Celsius; and 2.4 is

the coefficient when distillation results are determined in

degrees Fahrenheit The ethanol correction term is required

because the reduction in the T50resulting from the addition

of ethanol does not provide as much improvement in

drive-ability as would such a reduction by a hydrocarbon

Vapor-Liquid Ratio

The vaporization tendency of spark-ignition engine fuel can

also be expressed in terms of vapor-to-liquid ratio (V/L) at

temperatures approximating those found in critical parts of

the fuel system The standard test method is ASTM D5188,

Test Method for Vapor-Liquid Ratio Temperature

Determina-tion of Fuels (Evacuated Chamber Method) This method is

applicable to samples for which the determined temperature

is between 36 and 80
C and the V/L is between 8:1 and 75:1

The fuel temperature at a V/L of approximately 20

(TV/L ¼20) was shown to be indicative of the tendency of a

fuel to cause vapor lock, as evidenced by loss of power

dur-ing full-throttle accelerations V/L–temperature relationships

were originally developed for vehicles equipped with

carbu-retors and suction-type fuel pumps The applicability of such

relationships to late-model vehicles equipped with fuel

injec-tion and pressurized fuel systems has been shown by CRC

test programs Appendix X2 of ASTM D4814 includes a

com-puter method and a linear equation method that can be

used for estimating V/L of spark-ignition engine fuels from

vapor pressure and distillation test results However, until

recently these estimation methods were not applicable to

gasoline-oxygenate blends ASTM D4814 in Appendix X2 now

provides equations for correcting the estimated values

appli-cable to ethanol blends

Volatility and Performance

In general terms, the following relationships between ity and performance apply:

volatil-1 High vapor pressures and low 10 % evaporated tures are both conducive to ease of cold starting How-ever, under hot operating conditions, they are alsoconducive to vapor lock and increased vapor formation

tempera-in fuel tanks, carburetors, and fuel tempera-injectors The amount

of vapor formed in fuel tanks and carburetors, whichmust be contained by the evaporative emissions controlsystem, is related to the vapor pressure and distillationtemperatures Thus, a proper balance of vapor pressureand 10 % evaporated temperature must be maintainedand seasonally adjusted for good overall performance

2 Although vapor pressure is a factor in the amount ofvapor formed under vapor locking conditions, vaporpressure alone is not a good index A better index formeasuring the vapor locking performance of spark-igni-tion engine fuels is the temperature at which the V/L is

20 at atmospheric pressure The lower the temperature atwhich V/L¼ 20, the greater is the tendency to cause vaporlock and hot-fuel–handling driveability problems Vaporlock is much less of a problem for fuel-injected cars,which have pressurized fuel systems However, driveabil-ity symptoms are similar to carbureted vehicles; a too-volatile fuel in fuel-injected cars can cause hard startingand rough idling, and in the extreme, the car will not start

3 The distillation temperature at which 50 % of the fuelhas evaporated is a broad indicator of warm-up andacceleration performance under cold-starting conditions.The lower the 50 % evaporated temperature, the better

is the performance (This statement is not always validfor gasoline-oxygenate blends, especially those contain-ing alcohol.) The temperatures for 10 and 90 % evapo-rated are also indicators of warm-up performance undercold-starting conditions, but to a lesser degree than the

50 % evaporated temperature Lowering the 50 % orated point, within limits, also has been shown toreduce exhaust hydrocarbon emissions

evap-4 The temperatures for 90 % evaporated and the final ing point, or end point, indicate the amount of relativelyhigh-boiling components in gasoline A high 90 % evapo-rated temperature, because it is usually associated withhigher density and high-octane number components, maycontribute to improved fuel economy and resistance toknock If the 90 % evaporated temperature and the endpoint are too high, they can cause poor mixture distribu-tion in the intake manifold and combustion chambers,increased hydrocarbon emissions, excessive combustionchamber deposits, and dilution of the crankcase oil

boil-5 DI represents the entire distillation curve Lower values of

DI mean greater volatility, which equates to better start and warm-up driveability until some minimum level

cold-is reached where no further improvement cold-is observed Ifthe DI is too high, vehicle cold-start and warm-up drive-ability can be adversely affected Maximum DI for eachvolatility class is limited by ASTM D4814 and other specifi-cations developed by motor vehicle manufacturers and byfuel suppliers A DI specification limit allows a refinermore flexibility in blending spark-ignition engine fuel thatprovides proper cold-start and warm-up driveability, com-pared to tight restrictions on individual distillation points

As ambient temperature is reduced, fuels with lower DI

are required The impact of oxygenates on DI and

drive-ability is not well established Some testing has shown that

at the same DI level, poorer driveability occurs with

oxy-genated fuels Other data have not shown this effect The

oxygenate effect may depend on the ambient

tempera-ture, type of oxygenate, and DI level of the fuel The DI

equation now contains a correction for ethanol blends

The CRC continues to investigate this issue

ASTM D4814, Specification for Automotive

Spark-Igni-tion Engine Fuel, includes a table of six volatility classes for

vapor pressure, distillation temperatures, and DI, and a

sepa-rate vapor lock protection table of six volatility classes for

TV/L ¼20 A combination of limits from these two tables defines

the fuel volatility requirements for each month and

geo-graphic area of the United States The specification also

accounts for the EPA regulations on vapor pressure and state

implementation plan (SIP) vapor pressure limits approved by

the EPA These volatility characteristics have been established

on the basis of broad experience and cooperation between

fuel suppliers and manufacturers and users of automotive

vehicles and equipment Spark-ignition engine fuels meeting

this specification have usually provided satisfactory

perform-ance in typical passenger car service However, certain

equip-ment or operating conditions may require or permit

variations from these limits Modern vehicles, designed to

exacting tolerances for good emission control, fuel economy,

and driveability, may require more restrictive limits

OTHER PROPERTIES

In addition to providing acceptable antiknock performance

and volatility characteristics, automotive spark-ignition engine

fuels must also provide for satisfactory engine and fuel

sys-tem cleanliness and durability The following properties have

a direct bearing on the overall performance of a fuel

Workmanship and Contamination

A finished fuel is expected to be visually free of undissolved

water, sediment, and suspended matter It should be clear

and bright when observed at 21
C (70
F) It should also be

free of any adulterant or contaminant that may render the

fuel unacceptable for its commonly used applications

Physi-cal contamination may occur during refining or distribution

of the fuel Control of such contamination is a matter

requir-ing constant vigilance by refiners, distributors, and

market-ers Solid and liquid contamination can lead to restriction of

fuel metering orifices, corrosion, fuel line freezing, gel

for-mation, filter plugging, and fuel pump wear ASTM D2709,

Test Method for Water and Sediment in Distillate Fuels by

Centrifuge, or ASTM D2276/IP 216, Test Method for

Particu-late Contaminant in Aviation Fuel by Line Sampling, can be

used to determine the presence of contaminants Appendix

X6 of ASTM D4814 contains a recommendation that all fuel

dispensers be equipped with filters of 10-micron

(microme-ter) or less nominal pore size at point of delivery to the

customer

Petroleum products pick up microbes during refining,

distribution, and storage Most growth takes place where fuel

and water meet Therefore, it is most important to minimize

water in storage tanks Microbial contamination in fuel was

not much of a problem until lead was removed Appendix

X5 of ASTM D4814 discusses microbial contamination and

references ASTM D6469, Guide for Microbial Contamination

in Fuels and Fuel Systems

Lead ContentConstraints imposed by emission control regulations andhealth concerns have led to the exclusive availability ofunleaded fuels for street and highway use Leaded fuel is stillallowed for nonroad use, such as for farm equipment and forracing The lead content of unleaded fuel is limited to a maxi-mum of 0.013 g Pb/L (0.05 g Pb/gal), but typical lead contents

in U.S unleaded fuels are 0.001 g Pb/L or less Although theEPA regulations prohibit the deliberate addition of lead tounleaded fuels, some contamination by small amounts of leadcan occur in the distribution system Such occurrences are rare,because leaded fuel has been eliminated from the market.The following methods are suitable for determining theconcentration of lead in spark-ignition engine fuel:

FOR LEADED FUELASTM D3341, Test Method for Lead in Gasoline–Iodine Mono-chloride Method

ASTM D5059/IP 228, Test Methods for Lead in Gasoline byX-Ray Spectroscopy

FOR UNLEADED FUELASTM D3237, Test Method for Lead in Gasoline by AtomicAbsorption Spectroscopy

ASTM D3348, Test Method for Rapid Field Test for TraceLead in Unleaded Gasoline (Colorimetric Method)ASTM D5059/IP 228, Test Methods for Lead in Gasoline byX-Ray Spectroscopy

Phosphorus Content

In the past, phosphorus compounds were sometimes added toleaded fuels as combustion chamber deposit modifiers However,because phosphorus adversely affects exhaust emission controlsystem components, particularly the catalytic converter, todayEPA regulations limit its concentration in unleaded fuel to a max-imum of 0.0013 g P/L (0.005 g P/gal) Furthermore, phosphorusmay not be intentionally added to unleaded fuel in any concen-tration The concentration of phosphorus can be determined byASTM D3231, Test Method for Phosphorus in Gasoline

Manganese Content

In the 1970s, methylcyclopentadienyl manganese tricarbonyl(MMT) was added to some unleaded fuels for octane improve-ment However, the use of MMT was banned in 1977 in Califor-nia In October 1978, the EPA banned its use in unleaded fuelthroughout the United States because it increased vehiclehydrocarbon emissions in various test programs, including the63-vehicle CRC program in 1977 In 1995, after much testingand court action, MMT was granted a waiver by the EPA foruse at a maximum concentration of 0.008 g Mn/L (0.031 g Mn/gal) According to the EPA’s website, “the Agency determinedthat MMT added at 1/32 gpg Mn will not cause or contribute toregulated emissions failures of vehicles.” Nevertheless, the use

of MMT remains controversial The EPA’s website notes theagency’s uncertainty about the health risks of using MMT Themanganese content of spark-ignition engine fuel can be deter-mined by ASTM D3831, Test Method for Manganese in Gaso-line by Atomic Absorption Spectroscopy

Sulfur ContentCrude petroleum contains sulfur compounds, most of whichare removed during refining The maximum amount of sul-fur as specified in ASTM D4814 is 0.0080 mass percent,

which is the federal per-gallon maximum limit The federal

regulations also have a refinery annual average maximum

limit of 0.0030 mass percent There are a few exceptions for

qualified refineries that expire by the end of 2010

Sulfur oxides formed during combustion may be

con-verted to acids that promote rusting and corrosion of engine

parts and exhaust systems Sulfur oxides formed in the exhaust

are undesirable atmospheric pollutants However, the

contri-bution of automotive exhaust to total sulfur oxide emissions is

negligible Sulfur also reduces the effectiveness of exhaust gas

catalytic converters In 1996, California set an average

maxi-mum limit of 0.0030 mass percent and then at the end of 2003

lowered it to 0.0015 mass percent More details on sulfur

requirements are presented later in this chapter

The sulfur content of spark-ignition engine fuel can be

determined by the following methods:

• ASTM D1266/IP 107, Test Method for Sulfur in

Petro-leum Products (Lamp Method)

• ASTM D2622, Test Method for Sulfur in Petroleum Products

by Wavelength Dispersive X-Ray Fluorescence Spectrometry

• ASTM D3120, Test Method for Trace Quantities of Sulfur in

Light Liquid Hydrocarbons by Oxidative Microcoulometry

• ASTM D4045, Test Method for Sulfur in Petroleum

Prod-ucts by Hydrogenolysis and Rateometric Colorimetry

• ASTM D4294, Test Method for Sulfur in Petroleum and

Petroleum Products by Energy-Dispersive X-Ray

Fluores-cence Spectrometry

• ASTM D5453, Test Method for Determination of Total

Sulfur in Light Hydrocarbons, Spark Ignition Engine

Fuel and Engine Oil by Ultraviolet Fluorescence

• ASTM D6334, Test Method for Sulfur in Gasoline by

Wavelength Dispersive X-Ray Fluorescence

• ASTM D6445, Test Method for Sulfur in Gasoline by

Energy-Dispersive X-Ray Fluorescence Spectrometry

• ASTM D6920, Test Method for Total Sulfur in Naphthas,

Distillates, Reformulated Gasolines, Diesels, Biodiesels,

and Motor Fuel by Oxidative Combustion and

Electro-chemical Detection

• ASTM D7039, Test Method for Sulfur in Gasoline and

Diesel Fuel by Monochromatic Wavelength Dispersive

X-Ray Fluorescence Spectrometry

It is important to review the sulfur content determination

minimum and maximum levels before selecting a test method

to ensure it is applicable for the test sample of interest

The presence of free sulfur or reactive sulfur compounds

can be detected by ASTM D130/IP 154, Test Method for

Detec-tion of Copper Corrosion from Petroleum Products by the

Copper Strip Tarnish Test, or by ASTM D4952, Test Method

for Qualitative Analysis for Active Sulfur Species in Fuels and

Solvents (Doctor Test) Sulfur in the form of mercaptans can

be determined by ASTM D3227/IP 342, Test Method for (Thiol

Mercaptan) Sulfur in Gasoline, Kerosene, Aviation Turbine,

and Distillate Fuels (Potentiometric Method)

Gum and Stability

During storage, fuels can oxidize slowly in the presence of

air and form undesirable oxidation products such as

perox-ides and/or gum These products are usually soluble in the

fuel, but the gum may appear as a sticky residue on

evapora-tion These residues can deposit on carburetor surfaces, fuel

injectors, and intake manifolds, valves, stems, guides, and

ports ASTM D4814 limits the solvent-washed gum content

of spark-ignition engine fuel to a maximum of 5 mg/100 mL

ASTM D381/IP 131, Test Method for Gum Content in Fuels

by Jet Evaporation, is used to determine gum content.Many fuels are deliberately blended with nonvolatile oils

or additives or both, which remain as residues in the ration step of the gum test A heptane-washing step is, there-fore, a necessary part of the procedure to remove suchmaterials, so that the solvent washed gum may be deter-mined The unwashed gum content (determined before theheptanes-washing step) indicates the presence of nonvolatileoils or additives ASTM Test Method D381/IP 131 also is used

evapo-to determine the unwashed gum content There is no cation limit for unwashed gum content in ASTM D4814.Automotive fuels usually have a very low gum contentwhen manufactured but may oxidize to form gum duringextended storage ASTM D525/IP 40, Test Method for OxidationStability of Gasoline (Induction Period Method), is a test to indi-cate the tendency of a fuel to resist oxidation and gum forma-tion It should be recognized, however, that the method’scorrelation with actual field service may vary markedly underdifferent storage conditions and with different fuel blends Mostautomotive fuels contain special additives (antioxidants) to pre-vent oxidation and gum formation Some fuels also containmetal deactivators for this purpose Commercial fuels available

specifi-in service stations move rather rapidly from refspecifi-inery tion to vehicle usage and are not designed for extended storage.Fuels purchased for severe bulk storage conditions or for pro-longed storage in vehicle fuel systems generally have additionalamounts of antioxidant and metal deactivator added

produc-Although not designed for automotive fuel, ASTM D873,Test Method for Oxidation Stability of Aviation Fuels (Poten-tial Residue Method), is sometimes used to evaluate the sta-bility of fuel under severe conditions, and like ASTM D525,

it can indicate the tendency of the fuel to oxidize No lation has been established between the results of this testand actual automotive service, but the comparative rankings

corre-of fuels tested by D873 are corre-often useful

Peroxides are undesirable in automotive fuel becausethey can attack fuel system elastomers and copper commuta-tors in fuel pumps Peroxides can participate in an autocata-lytic reaction to form more peroxides, thus accelerating thedeterioration of fuel system components Also, peroxidesreduce the octane rating of the fuel Hydroperoxides andreactive peroxides can be determined by ASTM D3703, TestMethod for Peroxide Number of Aviation Turbine Fuels, or

by ASTM D6447, Test Method for Hydroperoxide Number ofAviation Turbine Fuels by Voltammetric Analysis

Density and Relative DensityASTM D4814 does not set limits on the density of spark-ignitionengine fuels, because the density is fixed by the other chemicaland physical properties of the fuel Density relates to the volu-metric energy content of the fuel—the more dense the fuel, thehigher is the volumetric energy content Density is important,also, because fuel is often bought and sold with reference to aspecific temperature, usually 15.6
C (60
F) Because the fuel isusually not at the specified temperature, volume correction fac-tors based on the change in density with temperature are used

to correct the volume to that temperature Volume correctionfactors for oxygenates differ somewhat from those for hydro-carbons, and work is in progress to determine precise correc-tion factors for gasoline-oxygenate blends

Rather than using absolute density (in units of kg/m3, forexample), relative density is often used Relative density, or

specific gravity, is the ratio of the mass of a given volume of

fuel at a given temperature to the mass of an equal volume of

water at the same temperature Most automotive fuels have

relative densities between 0.70 and 0.78 at 15.6
C (60
F)

The American Petroleum Institute (API) gravity is often

used as a measure of a fuel’s relative density, although this

practice is now discouraged with the move toward the use of

SI units API gravity is based on an arbitrary hydrometer scale

and is related to specific gravity at 15.6
C (60
F) as follows:

API Gravity; Deg: ¼sp grð15:6=15:6141:5
CÞ 131:5 ð1Þ

Fuel density is determined by ASTM D1298/IP 160, Test

Method for Density, Relative Density (Specific Gravity), or

API Gravity of Crude Petroleum and Liquid Petroleum

Prod-ucts by Hydrometer Method, or by ASTM D4052/IP 365, Test

Method for Density and Relative Density of Liquids by

Digi-tal Density Meter

Rust and Corrosion

Filter plugging and engine wear problems are reduced by

minimizing rust and corrosion in fuel distribution and

vehi-cle fuel systems Modifications of ASTM D665/IP 135, Test

Method for Rust-Preventing Characteristics of Inhibited

Min-eral Oil in the Presence of Water, are sometimes used to

measure rust protection of fuels

Silver Corrosion

Reactive trace sulfur compounds (elemental sulfur,

hydro-gen sulfide, and mercaptans) present in fuel under some

cir-cumstances can corrode or tarnish silver alloy fuel gage

in-tank sending units, causing them to fail To minimize the

failure of the silver fuel gage sending units, the fuel must

pass the silver corrosion test method described in Annex A1

in ASTM Specification D4814 The test method uses the

ASTM Test Method D130 test apparatus except a silver

cou-pon replaces the normal copper one ASTM is working to

develop a new silver corrosion test method ASTM D4814

limits the silver corrosion rating to a maximum of “1.”

Hydrocarbon Composition

The three major types of hydrocarbons in gasoline are the

sat-urates (paraffins, isoparaffins, naphthenes), olefins, and

aro-matics They are identified by ASTM D1319/IP 156, Test

Method for Hydrocarbon Types in Liquid Petroleum Products

by Fluorescent Indicator Adsorption This method ignores

oxy-genates in the fuel and only measures the percentages of

satu-rates, olefins, and aromatics in the hydrocarbon portion of the

fuel Therefore, the results must be corrected for any

oxygen-ates that are present ASTM D6293, Test Method for

Oxygen-ates and Paraffin, Olefin, Naphthene, Aromatic (O-PONA)

Hydrocarbon Types in Low-Olefin Spark Ignition Engine Fuel

by Gas Chromatography, is another method A more detailed

compositional analysis can be determined using one of the

fol-lowing methods: ASTM D6729, Test Method for

Determina-tion of Individual Components in Spark IgniDetermina-tion Engine Fuels

by 100 Metre Capillary High Resolution Gas Chromatography,

ASTM D6730, Test Method for Determination of Individual

Components in Spark Ignition Engine Fuels by 100 Metre

Capillary (with Precolumn) High Resolution Gas

Chromatog-raphy, or ASTM D6733, Test Method for Determination of

Individual Components in Spark Ignition Engine Fuels by

50 Metre Capillary High Resolution Gas Chromatography

The amount of benzene can be determined by ASTMD4053, Test Method for Benzene in Motor and Aviation Gaso-line by Infrared Spectroscopy The amounts of benzene andother aromatics can be determined by ASTM D3606, TestMethod for Benzene and Toluene in Finished Motor and Avia-tion Gasoline by Gas Chromatography, although there are inter-ferences from methanol and ethanol ASTM D5580, TestMethod for the Determination of Benzene, Toluene, Ethylben-zene, p/m-Xylene, o-Xylene, C9 and Heavier Aromatics, andTotal Aromatics in Finished Gasoline by Gas Chromatography,and ASTM D5769, Test Method for Determination of Benzene,Toluene, and Total Aromatics in Finished Gasoline by Gas Chro-matography/Mass Spectrometry, can also be used Anothermethod for the determination of aromatics is ASTM D5986,Test Method for Determination of Oxygenates, Benzene, Tolu-ene, C8-C12Aromatics and Total Aromatics in Finished Gasoline

by Gas Chromatography/Fourier Transform Infrared copy The benzene content of reformulated gasoline is limited

Spectros-to 1 volume percent by legislation, because benzene is ered toxic and a carcinogen Beginning in 2011 under theMobile Source Air Toxics (MSAT) Rule, benzene will be con-trolled for all gasoline at a refinery maximum average of 0.62volume percent with a credit and trading program

consid-The total olefin content of automotive fuel can be mined by ASTM D6296, Test Method for Total Olefins inSpark-Ignition Engine Fuels by Multi-dimensional Gas Chro-matography, or by ASTM D6550, Test Method for Determina-tion of Olefin Content of Gasolines by Supercritical-FluidChromatography The latter method has recently been desig-nated by the California Air Resources Board as their stand-ard test method for olefins

deter-OxygenatesOxygenates are discussed in detail later in this chapter, andadditional information on oxygenates is presented in Chapter 3.Nevertheless, it is appropriate to mention here that alcohols

or ethers are often added to gasoline to improve octane ing, extend the fuel supply, or reduce vehicle emissions Cer-tain governmental regulations require such addition, as will

rat-be discussed Consequently, it is often necessary to mine the oxygenate content or the oxygen content of spark-ignition engine fuels ASTM D4815, Test Method for Determi-nation of MTBE, ETBE, TAME, DIPE, tertiary-Amyl Alcoholand C1 to C4 Alcohols in Gasoline by Gas Chromatography,can be used to determine the identity and concentrations oflow-molecular-weight aliphatic alcohols and ethers Alterna-tive methods for determining the amounts of oxygenates areASTM D5599, Test Method for Determination of Oxygenates

deter-in Gasoldeter-ine by Gas Chromatography and Oxygen SelectiveFlame Ionization Detection, and ASTM D5845, Test Methodfor Determination of MTBE, ETBE, TAME, DIPE, Methanol,Ethanol and tert-Butanol in Gasoline by Infrared Spectros-copy Appendix X4 in Specification D4814 describes a proce-dure for calculating the oxygen content of the fuel from theoxygenate content

AdditivesFuel additives are used to provide or enhance various per-formance features related to the satisfactory operation ofengines, as well as to minimize fuel handling and storageproblems These chemicals complement refinery processing

in attaining the desired level of product quality The mostcommonly used additives are listed in Table 1 With few

exceptions, standardized test methods are not available to

determine the identity and concentration of specific additives

As mentioned previously, standard test methods are available

for determining lead, manganese, and oxygenate content

U.S LEGAL REQUIREMENTS FOR

SPARK-IGNITION ENGINE FUEL

Fuel Composition

The U.S EPA has established vehicle exhaust and

evapora-tive emissions standards as part of the U.S effort to attain

acceptable ambient air quality To meet these EPA vehicle

requirements, extensive modifications have been made to

automotive engines and emissions systems Because some

fuel components can harm the effectiveness of vehicle

emis-sions control systems, the EPA also exercises control over

automotive fuels EPA regulations on availability of unleaded

automotive fuels, and on limits of lead, phosphorus, and

manganese contents in the fuel, have been mentioned

In addition, the Clean Air Act Amendments of 1977

pro-hibit the introduction into U.S commerce, or increases in

the concentration of, any fuel or fuel additive for use in

1975 and later light-duty motor vehicles, which is not

“substantially similar” to the fuel or fuel additives used in

the emissions certification of such vehicles

The EPA considers fuels to be “substantially similar” if

the following criteria are met:

1 The fuel must contain carbon, hydrogen, and oxygen,

nitrogen, and/or sulfur, exclusively, in the form of some

combination of the following:

a Hydrocarbons

b Aliphatic ethers

c Aliphatic alcohols other than methanol(i) Up to 0.3 % methanol by volume(ii) Up to 2.75 % methanol by volume with anequal volume of butanol or higher-molecular-weight alcohol

d A fuel additive at a concentration of no more than0.25 % by weight, which contributes no more than

15 ppm sulfur by weight to the fuel

2 The fuel must contain no more than 2.0 % oxygen byweight, except fuels containing aliphatic ethers and/oralcohols (excluding methanol) and must contain no morethan 2.7 % oxygen by weight (Note As mentioned previ-ously, ethanol and certain other alcohols have receivedwaivers allowing as much as 3.7 % oxygen in the fuel.)

3 The fuel must possess, at the time of manufacture, all ofthe physical and chemical characteristics of an unleadedgasoline, as specified by ASTM Standard D4814-88, for atleast one of the Seasonal and Geographical VolatilityClasses specified in the standard (Note The EPA’s Febru-ary 11, 1991, notice specified the 1988 version of D4814.)

4 The fuel additive must contain only carbon, hydrogen,and any one or all of the following elements: oxygen,nitrogen, and/or sulfur

Fuels or fuel additives that are not “substantially similar”may only be used if a waiver of this prohibition is obtainedfrom the EPA Manufacturers of fuels and fuel additives mustapply for such a waiver and must establish to the satisfaction

of the EPA that the fuel or additive does not cause or ute to a failure of any emission control device or system overthe useful life of the vehicle for which it was certified Underprior law, if the EPA Administrator had not acted to grant or

contrib-TABLE 1—Commercial Spark-Ignition Engine Fuel Additives

Oxidation inhibitors (antioxidants) Minimize oxidation and gum formation Aromatic amines and hindered phenols Corrosion inhibitors Inhibit ferrous corrosion in pipelines, stor-

age tanks, and vehicle fuel systems

Carboxylic acids and carboxylates

Silver corrosion inhibitors Inhibit corrosion of silver fuel gage sender

units

Substituted thiadiazole

cata-lyzed by ions of copper and other metals

Chelating agent

Carburetor/injector detergents Prevent and remove deposits in

carburet-ors and port fuel injectcarburet-ors

Amines, amides, and amine carboxylates

Deposit control additives Remove and prevent deposits throughout

fuel injectors, carburetors, intake ports and valves, and intake manifold

Polybutene amines and polyether amines

improv-ing water separation

Polyglycol derivatives

Anti-icing additives Minimize engine stalling and starting

problems by preventing ice formation in the carburetor and fuel system

Surfactants, alcohols, and glycols

Antiknock compounds Improve octane quality of automotive fuel Lead alkyls and methylcyclopentadienyl

manganese tricarbonyl

fluorescent compounds

Note Some materials are multifunctional or multipurpose additives, performing more than one function Source: SAE J312-Automotive Gasolines, Society

of Automotive Engineers, Inc.

deny the waiver within 180 days after its filing, the waiver

was treated as granted The waiver process has been changed

to now require the EPA to act within 270 days The EPA has

granted several waivers for gasoline-oxygenate blends The

reader is referred to the EPA for the latest information on

waivers and the conditions under which they may be used

Any fuel or fuel additive that had a waiver as of May 27,

1994, has to have had a supplemental registration with

addi-tional toxics data by November 27, 1994, to continue

market-ing the material These registered products are subjected to

a three-tier toxicological testing program A new fuel or

addi-tive that was not registered as of May 27, 1994, will not be

registered until all Tier 1 and Tier 2 information has been

supplied At present, no methanol-containing fuel additive

has obtained a supplemental registration, and therefore, the

addition of methanol to gasoline is prohibited

Volatility

Concerns over increased evaporative emissions prompted the

EPA to promulgate regulations that, beginning in 1989,

reduced fuel vapor pressure Spark-ignition engine fuels sold

between June 1 and September 15 of each year were limited

to maximum vapor pressures of 9.0, 9.5, or 10.5 psi, depending

on the month and the region of the country (Vapor pressure

restrictions applied to fuels in the distribution system as early

as May 1.) In 1992, the EPA implemented Phase II of the

vola-tility controls, which limited fuels sold between June 1 and

September 15 to a maximum vapor pressure of 9.0 psi The

regulations are more restrictive in ozone nonattainment areas

in the southern and western areas of the United States, where

fuels sold during certain months of the control period are

lim-ited to a maximum vapor pressure of 7.8 psi The EPA permits

conventional (i.e., not reformulated) fuels containing between

9 and 10 volume percent ethanol to have a vapor pressure 1.0

psi higher than the maximum limit for other fuels

California was the first state to control spark-ignition

engine fuel vapor pressure and, in 1971, mandated a

maxi-mum vapor pressure limit of 9.0 psi By 1992, the maximaxi-mum

vapor pressure limit was lowered to 7.8 psi In 1996, it was

further lowered to 7.0 psi maximum A number of other

states have set maximum limits on vapor pressure in certain

areas as part of their SIPs The EPA vapor pressure limits

and the EPA-approved SIP limits are an integral part of

ASTM D4814

Sulfur Regulations

California’s Phase 2 reformulated gasoline specification

lim-ited the maximum sulfur content of fuel to 30 ppm average,

with an 80 ppm cap On December 31, 2003, new Phase 3

specifications lowered the sulfur maximum to 15 ppm

aver-age and the cap limits to 60 ppm The cap limits were

fur-ther reduced to 30 ppm on December 31, 2005

Federal Tier 2 regulations required that in 2004, refiners

meet an annual corporate average sulfur level of 120 ppm,

with a cap of 300 ppm In 2005, the required refinery average

was 30 ppm, with a corporate average of 90 ppm and a cap of

300 ppm Both of the average standards can be met with the

use of credits generated by other refiners who reduce sulfur

levels early Beginning in 2006, refiners were required to meet

a final 30 ppm average with a cap of 80 ppm Fuel produced

for sale in parts of the western United States must comply

with a 150-ppm refinery average and a 300-ppm cap through

2006 but are required to meet the 30-ppm average/80-ppm

cap by 2007 Refiners demonstrating a severe economic ship may apply for an extension of up to two years The regu-lations provide for some special sulfur limit exemptions forsmall refineries relating to the early introduction of ultralowsulfur diesel fuel, but these all expire at the end of 2010 Theregulations include an averaging program Some statesinclude fuel sulfur limits in their SIPs

hard-Sampling, Containers, and Sample HandlingCorrect sampling procedures are critical to obtain a samplerepresentative of the lot intended to be tested ASTM D4057,Practice for Manual Sampling of Petroleum and PetroleumProducts, provides several procedures for manual sampling.ASTM D4177, Practice for Automatic Sampling of Petroleumand Petroleum Products, provides automatic sampling proce-dures For volatility determinations of a sample, ASTMD5842, Practice for Sampling and Handling of Fuels for Vol-atility Measurement, contains special precautions for sam-pling and handling techniques to maintain sample integrity.ASTM D4306, Practice for Aviation Fuel Sample Containersfor Tests Affected by Trace Contamination, should be used

to select appropriate containers, especially for tests sensitive

to trace contamination Also ASTM D5854, Practice for ing and Handling of Liquid Samples of Petroleum and Petro-leum Products, provides procedures for container selectionand sample mixing and handling For octane number deter-mination, protection from light is important Collect andstore fuel samples in an opaque container, such as a darkbrown glass bottle, metal can, or minimally reactive plasticcontainer, to minimize exposure to UV emissions from sour-ces such as sunlight or fluorescent lamps

Mix-Oxygenated Fuel Programs and Reformulated Spark-Ignition Engine Fuel

In January 1987, Colorado became the first state to mandatethe use of oxygenated fuels in certain areas during the win-ter months to reduce vehicle carbon monoxide (CO) emis-sions By 1991, areas in Arizona, Nevada, New Mexico, andTexas had also implemented oxygenated-fuels programs.The 1990 amendments to the Clean Air Act require theuse of oxygenated fuels in 39 CO nonattainment areas dur-ing the winter months, effective November 1992 The pro-gram had to be implemented by the states using one of thefollowing options If averaging is allowed, the average fueloxygen content must be at least 2.7 mass percent, with aminimum oxygen content of 2.0 mass percent in each gallon

of fuel Without averaging, the minimum oxygen content ofeach fuel must be 2.7 mass percent (This is equivalent toabout 7.3 volume percent ethanol or 15 volume percentMTBE.) The first control period was November 1, 1992,through January or February 1993, depending on the area.Subsequent control periods can be longer in some areas.Over time a number of states have come into conformancewith CO regulations, and only about eight states still requirewintertime ethanol requirements

Beginning in 1995, the nine areas with the worst ozonelevels, designated as extreme or severe, were required to sellreformulated spark-ignition engine fuel Later four additionalareas were added, but two are still pending implementation.Areas with less severe ozone levels were permitted to partici-pate in (“opt-in” to) the program Initially, about 37 otherozone nonattainment areas opted into participating in theprogram Since then, about 17 have chosen to opt-out of the

program The reformulated fuel program is directed toward

reducing ground level ozone and toxics concentrations

The Clean Air Act Amendments of 1990 set specific

guidelines for reformulated spark-ignition engine fuel for

1995 through 1997 Fuels sold in the control areas were

required to meet the specifications of what is called the

“Simple Model.” Limits were established for vapor pressure

(June 1 through September 15) and benzene content,

deposit control additives were required in all fuels, and the

use of heavy-metal additives was prohibited A minimum

oxy-gen content of 2.0 mass percent was required all year

(aver-aged) The sulfur and olefin contents and the 90 %

evaporated temperature were not allowed to exceed 125 %

of the average values of the refiner’s 1990 fuels The use of

the “Simple Model” expired December 31, 1997

Effective January 1, 1998, a “Complex Model” had to be

used for determining conformance to standards for

reformu-lated fuel blends Fuel properties in the “Complex Model”

included vapor pressure, oxygen content, aromatics content,

benzene content, olefins content, sulfur content, E200 and

E300 (distillation properties), and the particular oxygenate

used The benzene limit, the ban on heavy metals, the

mini-mum oxygen content, and the requirement for a deposit

control additive remained the same as under the “Simple

Model.” As a result of the adoption of the RFS, the

mini-mum oxygen requirement for reformulated fuel was

elimi-nated effective in 2006

The Clean Air Act Amendments of 1990 also contain an

antidumping provision In the production of reformulated

spark-ignition engine fuel, a refiner cannot “dump” into its

“conventional” fuel pool those polluting components

removed from the refiner’s reformulated fuel These

require-ments apply to all fuel produced, imported, and consumed

in the United States and its territories

In 1992, California instituted its Phase 1 fuel

regula-tions, which were followed in 1996 by its Phase 2

reformu-lated fuel regulations The Phase 2 specifications controlled

vapor pressure, sulfur content, benzene content, aromatics

content, olefins content, 50 % evaporated point, and 90 %

evaporated point These same variables were used in

Califor-nia’s “Predictive Model,” which is similar to the federal

“Complex Model,” but with different equations Beginning

December 31, 2003, California required fuel to meet a Phase

3 reformulated fuel regulation

An excellent source of information on reformulated fuels

(federal and California) and their associated requirements can

be found in the ASTM Committee D02 on Petroleum Products

and Lubricants Research Report D02: 1347, Research Report

on Reformulated Spark-Ignition Engine Fuel for current

fed-eral and state future reformulated fuel (cleaner burning fuels)

requirements and approved test methods

Renewable Fuel Standard

In 2007, the EPA finalized regulations for the RFS, which was

authorized by the Energy Policy Act of 2005 The RFS

estab-lishes a minimum requirement for the volume of renewable

fuels blended into automotive spark-ignition and diesel fuels

The national minimum volume requirement started at 4.0

bil-lion gallons per year of renewable fuel in 2006 and increases

to 7.5 billion gallons per year in 2012 Each producer and

importer of fuel in the United States is obligated to

demon-strate compliance with this requirement based on the pro

rata share of fuel it produces or imports With the passage of

the Energy Independence and Security Act (EISA) of 2007,the amount of renewable fuels required was increased to 15.2billion gallons per year in 2012 and ends with a requirement

of 36.0 billion gallons per year by 2022 The proportionalrequirement for cellulosic biofuel in the act begins in 2010and scales up to 16.0 billion gallons per year by 2022

Deposit Control Additive RequirementsCalifornia in 1992 and the EPA in 1995 required the use ofdeposit control additives to minimize the formation of fuelinjector and intake valve deposits Both California and theEPA required that additives be certified in specified test fuels

in vehicle tests The fuel injector test procedure is ASTMD5598, Test Method for Evaluating Unleaded AutomotiveSpark-Ignition Engine Fuel for Electronic Port Fuel InjectorFouling, and the intake valve deposit test procedure is ASTMD5500, Test Method for Vehicle Evaluation of UnleadedAutomotive Spark-Ignition Engine Fuel for Intake ValveDeposit Formation ASTM developed more recent, nonve-hicle versions of these tests for consideration by the EPA.These are ASTM D6201, Test Method for Dynamometer Eval-uation of Unleaded Spark-Ignition Engine Fuel for IntakeValve Deposit Formation, and ASTM D6421, Test Method forEvaluating Automotive Spark-Ignition Engine Fuel for Elec-tronic Port Fuel Injector Fouling by Bench Procedure.GASOLINE-OXYGENATE BLENDS

Blends of gasoline with oxygenates are common in the U.S.marketplace and, in fact, are required in certain areas, as dis-cussed previously These blends consist primarily of gasolinewith substantial amounts of oxygenates, which are oxygen-containing, ashless, organic compounds such as alcohols andethers The most common oxygenate in the United States isethanol MTBE was widely used but has been phased out inmany states because of concern over ground water pollution

It is still used in some European countries as an octane ming agent Other ethers, such as ethyl tert-butyl ether(ETBE),tert-amyl methyl ether (TAME), and diisopropyl ether(DIPE), are receiving some attention, but have not yetachieved widespread use Like MTBE, these ethers also arebanned in some states Methanol/tert-butyl alcohol mixtureswere blended with gasoline on a very limited scale in theearly 1980s but cannot be used now until they have a supple-mental toxics registration When methanol was used as ablending component, it had to be accompanied by a cosol-vent (a higher-molecular-weight alcohol) to help preventphase separation of the methanol and gasoline in the pres-ence of trace amounts of water EPA waiver provisions alsorequired corrosion inhibitors in gasoline-methanol blends.ASTM D4806, Specification for Denatured Fuel Ethanolfor Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel, describes a fuel-grade ethanol that issuitable for blending with gasoline ASTM D5983, Specifica-tion for Methyl Tertiary-Butyl Ether (MTBE) for DownstreamBlending with Automotive Spark-Ignition Fuel, provides lim-its for blending MTBE in gasoline

trim-Sampling of Gasoline-Oxygenate BlendsSampling of blends can be conducted according to the pro-cedures discussed earlier; however, water displacement mustnot be used, because of potential problems associated withthe interaction of water with oxygenates contained in somespark-ignition engine fuels

Test Methods for Gasoline-Oxygenate Blends

Some of the test methods originally developed for gasoline

can be used for gasoline-oxygenate blends, while certain

other test methods for gasoline are not suitable for blends

To avoid the necessity of determining in advance whether a

fuel contains oxygenates, ASTM D4814 now specifies test

methods that can be used for both gasolines and

gasoline-oxygenate blends This has been made possible by

experi-ence with some test methods, modification of existing test

methods, and the development of new ones

Gasoline-ethanol blends are not included in the scopes of many test

methods, and the precision statements do not apply ASTM

is working to modify the scopes and develop precision

statements for the test methods specified in ASTM D4814

to cover gasoline-ethanol blends Additional test methods

and limits need to be developed to protect against

incom-patibility with elastomers and plastics, corrosion of metals,

and other factors that may affect vehicle performance and

durability

In general, the test methods discussed previously for

determining distillation temperatures, lead content, sulfur

content, copper corrosion, solvent-washed gum, and

oxida-tion stability can be used for both gasolines and

gasoline-oxy-genate blends In some cases, standard solutions with which

to calibrate the instrument must be prepared in the same

type of fuel blend as the sample to be analyzed

Some of the test methods for vapor pressure and vapor/

liquid ratio are sensitive to the presence of oxygenates in the

fuel, and approved procedures were discussed earlier in this

chapter

Water Tolerance

The term “water tolerance” is used to indicate the ability of a

gasoline-alcohol blend to dissolve water without phase

separa-tion Gasoline and water are almost entirely immiscible and

will readily separate into two phases Gasoline-alcohol blends

will dissolve some water but will also separate into two phases

when contacted with more water than they can dissolve This

water can be absorbed from ambient air or can occur as

liq-uid water in the bottom of tanks in the storage, distribution,

and vehicle fuel system When gasoline-alcohol blends are

exposed to a greater amount of water than they can dissolve,

about 0.1 to 0.7 mass percent water, they separate into a

lower alcohol-rich aqueous phase and an upper alcohol-poor

hydrocarbon phase The aqueous phase can be corrosive to

metals, and the engine cannot operate on it Because the fuel

pump is at the bottom of an automotive fuel tank, the

aque-ous phase will be sent to the engine if the fuel separates

Therefore, this type of phase separation is undesirable

Sepa-ration occurs more readily with the lower-molecular-weight

alcohols and at lower alcohol concentrations With ethanol,

the 10 volume percent levels used in the United States are

eas-ily handled; however, the 5 volume percent levels used in

Europe are much more sensitive to separation Several years

of experience in California with 5.7 volume percent ethanol

has shown no phase separation problems using ethanol

meet-ing a 1.0 volume percent maximum water content limit

Phase separation can usually be avoided if the fuels are

sufficiently water free initially and care is taken during

dis-tribution to prevent contact with water Formation of a haze

must be carefully distinguished from separation into two

dis-tinct phases with a more or less disdis-tinct boundary Haze

for-mation is not grounds for rejection Actual separation into

two distinct phases is the criterion for failure The testmethod originally developed to measure the water tolerance

of ethanol blends was determined in an interlaboratorystudy to not be sufficiently accurate and was withdrawn Thelimits were removed from the specification section of ASTMD4814 and placed in Appendix X8 for reference The needfor a water tolerance test is still thought to be important,and a water tolerance specification would be included inASTM D4814 if a suitable test can be developed

Compatibility with Plastics and ElastomersPlastics and elastomers used in current automotive fuel sys-tems such as gaskets, O-rings, diaphragms, filters, seals, etc.,may be affected in time by exposure to motor fuels Theseeffects include dimensional changes, embrittlement, soften-ing, delamination, increase in permeability, loss of plasticiz-ers, and disintegration Certain gasoline-oxygenate blendscan aggravate these effects

The effects depend on the type and amount of the genates in the blend, the aromatics content of the gasoline,the generic polymer and specific composition of the elasto-meric compound, the temperature and duration of contact,and whether the exposure is to liquid or vapor

oxy-Currently, there are no generally accepted tests that relate with field experience to allow estimates of tolerance

cor-of specific plastics or elastomers to oxygenates

Metal CorrosionCorrosion of metals on prolonged contact with gasolines alonecan be a problem, but it is generally more severe with gasoline-alcohol blends When gasoline-alcohol blends are contacted bywater, the aqueous phase that separates is particularly aggres-sive in its attack on fuel system metals The tern (lead-tin alloy)coating on fuel tanks and aluminum, magnesium, and zinccastings and steel components such as fuel senders, fuel lines,pump housings, and injectors are susceptible

A number of test procedures, other than long-term cle tests, have been used or proposed to evaluate the corro-sive effects of fuels on metals The tests range from staticsoaking of metal coupons to operation of a complete auto-motive fuel system None of these tests has yet achieved thestatus of an ASTM standard

vehi-Applicable ASTM Specifications

D4806 Specification for Denatured Fuel Ethanol for

Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel

D4814 Specification for Automotive Spark-Ignition Engine

Fuel D5797 Specification for Fuel Methanol (M70-M85) for

Automotive Spark-Ignition Engines D5798 Specification for Fuel Ethanol (Ed75-Ed85) for

Automotive Spark-Ignition Engines D5983 Specification for Methyl Tertiary-Butyl Ether

(MTBE) for Downstream Blending with motive Spark-Ignition Engine Fuel

Auto-D02:1347 Committee D02 Research Report on Reformulated

Spark-Ignition Engine Fuel

Applicable ASTM/IP Test Methods

Before using any test method, the scope shall be reviewed to make

sure the test method is applicable to the product being tested and

that the specified measurement range covers the area of interest.

D86 Test Method for Distillation of Petroleum

Products at Atmospheric Pressure D130 154 Test Method for Detection of Copper

Corrosion from Petroleum Products by the Copper Strip Tarnish Test

D323 Test Method for Vapor Pressure of

Petro-leum Products (Reid Method) D381 Test Method for Gum Content in Fuels by

Jet Evaporation D525 40 Test Method for Oxidation Stability of

Gasoline (Induction Period Method) D665 135 Test Method for Rust-Preventing Character-

istics of Inhibited Mineral Oil in the ence of Water

Pres-D873 138 Test Method for Oxidation Stability of

Avia-tion Fuels (Potential Residue Method) D1266 107 Test Method for Sulfur in Petroleum Prod-

ucts (Lamp Method) D1298 160 Test Method for Density, Relative Density

(Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products

by Hydrometer Method D1319 156 Test Method for Hydrocarbon Types in Liq-

uid Petroleum Products by Fluorescent cator Adsorption

Indi-D2276 216 Test Method for Particulate Contaminant in

Aviation Fuel by Line Sampling D2622 Test Method for Sulfur in Petroleum Prod-

ucts by Wavelength Dispersive X-Ray rescence Spectrometry

Fluo-D2699 237 Test Method for Research Octane Number

of Spark-Ignition Engine Fuel D2700 236 Test Method for Motor Octane Number of

Spark-Ignition Engine Fuel D2709 Test Method for Water and Sediment in

Distillate Fuels by Centrifuge D2885 360 Test Method for Research and Motor Method

Octane Ratings Using On-Line Analyzers D3120 Test Method for Trace Quantities of Sulfur

in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry

D3227 342 Test Method for (Thiol Mercaptan) Sulfur in

Gasoline, Kerosene, Aviation Turbine, and Distillate Fuels (Potentiometric Method) D3231 Test Method for Phosphorus in Gasoline

D3237 Test Method for Lead in Gasoline by Atomic

Absorption Spectroscopy

D3341 Test Method for Lead in Gasoline–Iodine

Monochloride Method D3348 Test Method for Rapid Field Test for Trace

Lead in Unleaded Gasoline (Colorimetric Method)

D3606 Test Method for Determination of Benzene

and Toluene in Finished Motor and Aviation Gasoline by Gas Chromatography

D3703 Test Method for Peroxide Number of

Aviation Turbine Fuels D3710 Test Method for Boiling Range Distribution

of Gasoline and Gasoline Fractions by Gas Chromatography

D3831 Test Method for Manganese in Gasoline by

Atomic Absorption Spectroscopy D4045 Test Method for Sulfur in Petroleum Products

by Hydrogenolysis and Rateometric Colorimetry D4052 365 Test Method for Density and Relative Den-

sity of Liquids by Digital Density Meter D4053 Test Method for Benzene in Motor and

Aviation Gasoline by Infrared Spectroscopy D4057 Practice for Manual Sampling of Petroleum

and Petroleum Products D4177 Practice for Automatic Sampling of

Petroleum and Petroleum Products D4294 Test Method for Sulfur in Petroleum and

Petroleum Products by Energy-Dispersive X-Ray Fluorescence Spectrometry D4306 Practice for Aviation Fuel Sample Containers

for Tests Affected by Trace Contamination D4815 Test Method for Determination of MTBE,

ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C 1 to C 4 Alcohols in Gasoline by Gas Chromatography

D4952 Test Method for Qualitative Analysis for

Active Sulfur Species in Fuels and Solvents (Doctor Test)

D4953 Test Method for Vapor Pressure of Gasoline

and Gasoline-Oxygenate Blends (Dry Method)

D5059 228 Test Methods for Lead in Gasoline by X-Ray

Spectroscopy D5188 Test Method for Vapor-Liquid Ratio Tem-

perature Determination of Fuels (Evacuated Chamber Method)

D5190 Test Method for Vapor Pressure of

Petro-leum Products (Automatic Method) D5191 Test Method for Vapor Pressure of Petro-

leum Products (Mini Method) D5453 Test Method for Determination of Total

Sulfur in Light Hydrocarbons, Spark Ignition Engine Fuel and Engine Oil by Ultraviolet Fluorescence

ASTM IP Title

D5482 Test Method for Vapor Pressure of

Petroleum Products (Mini Atmospheric)

Method-D5500 Test Method for Vehicle Evaluation of

Unleaded Automotive Spark-Ignition Engine Fuel for Intake Valve Deposit Formation D5580 Test Method for Determination of Benzene,

Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C 9 and Heavier Aromatics, and Total Aromatics in Finished Gasoline by Gas Chromatography

D5598 Test Method for Evaluating Unleaded

Auto-motive Spark-Ignition Engine Fuel for tronic Port Fuel Injector Fouling

Elec-D5599 Test Method for Determination of

Oxygen-ates in Gasoline by Gas Chromatography and Oxygen Selective Flame Ionization Detection

D5769 Test Method for Determination of Benzene,

Toluene, and Total Aromatics in Finished Gasoline by Gas Chromatography/Mass Spectrometry

D5842 Practice for Sampling and Handling of Fuels

for Volatility Measurement D5845 Test Method for Determination of MTBE,

ETBE, TAME, DIPE, Methanol, Ethanol and tert-Butanol in Gasoline by Infrared Spectroscopy

D5854 Practice for Mixing and Handling of Liquid

Samples of Petroleum and Petroleum Products D5986 Test Method for Determination of Oxygen-

ates, Benzene, Toluene, C 8 -C 12 Aromatics and Total Aromatics in Finished Gasoline by Gas Chromatography/Fourier Transform Infrared Spectroscopy

D6201 Test Method for Dynamometer Evaluation

of Unleaded Spark-Ignition Engine Fuel for Intake Valve Deposit Formation

D6293 Test Method for Oxygenates and Paraffin,

Olefin, Naphthene, Aromatic (O-PONA) Hydrocarbon Types in Low-Olefin Spark Ignition Engine Fuel by Gas

Chromatography D6296 Test Method for Total Olefins in Spark-

Ignition Engine Fuels by Multi-dimensional Gas Chromatography

D6334 Test Method for Sulfur in Gasoline by

Wavelength Dispersive X-Ray Fluorescence

D6378 Test Method for Determination of Vapor

Pressure (VP X ) of Petroleum Products, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures (Triple Expansion Method) D6421 Test Method for Evaluating Automotive

Spark-Ignition Engine Fuel for Electronic Port Fuel Injector Fouling by Bench Procedure

D6445 Test Method for Sulfur in Gasoline by

Energy-Dispersive X-Ray Fluorescence Spectrometry

D6447 Test Method for Hydroperoxide Number of

Aviation Turbine Fuels by Voltammetric Analysis

D6469 Guide for Microbial Contamination in Fuels

and Fuel Systems D6550 Test Method for Determination of Olefin

Content of Gasolines by Supercritical-Fluid Chromatography

D6729 Test Method for Determination of

Individ-ual Components in Spark Ignition Engine Fuels by 100 Metre Capillary High Resolu- tion Gas Chromatography

D6730 Test Method for Determination of

Individ-ual Components in Spark Ignition Engine Fuels by 100 Metre Capillary (with Precol- umn) High Resolution Gas Chromatography D6733 Test Method for Determination of Individ-

ual Components in Spark Ignition Engine Fuels by 50 Metre Capillary High Resolution Gas Chromatography

D6920 Test Method for Total Sulfur in Naphthas,

Distillates, Reformulated Gasolines, Diesels, Biodiesels, and Motor Fuel by Oxidative Combustion and Electrochemical Detection

D7039 Test Method for Sulfur in Gasoline and

Die-sel Fuel by Monochromatic Wavelength persive X-Ray Fluorescence Spectrometry D7096 Test Method for Determination of the Boil-

Dis-ing Range Distribution of Gasoline by Bore Capillary Gas Chromatography D7344 Test Method for Distillation of Petroleum

Wide-Products at Atmospheric Pressure (Mini Method)

D7345 Test Method for Distillation of Petroleum

Products at Atmospheric Pressure (Micro Distillation Method)

Fuel Oxygenates

Marilyn J Herman1and Lewis M Gibbs2

FUEL OXYGENATES ARE WIDELY USED IN THE

United States In the late 1970s and early 1980s, as lead

anti-knocks were removed from motor gasoline, gasoline

pro-ducers used oxygenates to offset the loss in octane number

from the removal of lead In the 1990s, oxygenates were

required by the government as an emission reduction control

strategy More recently, the United States has required the use

of renewable fuels in order to help reduce U.S dependence

on foreign sources of oil In December 2007, the President

signed into law the Energy Independence and Security Act of

2007 (P.L 110-140) The Energy Independence and Security

Act of 2007 (EISA) significantly expands and increases the

Renewable Fuels Standard established under the Energy

Pol-icy Act of 2005 requiring the use of 9.0 billion gallons of

renewable fuel in 2008, increasing to 36 billion gallons by

2022 In 2022, 21 billion gallons of the total renewable fuels

requirement must be obtained from cellulosic ethanol and

other advanced biofuels

Under the Clean Air Act, oxygenates have been used as

an emission control strategy to reduce carbon monoxide

(CO) in wintertime oxygenated fuel programs and as a

required component in federal reformulated gasoline

pro-grams to help reduce ozone The Clean Air Act Amendments

(CAA) of 1990 require states with areas exceeding the

national ambient air quality standard for carbon monoxide

to implement programs requiring the sale of oxygenated

gas-oline containing a minimum of 2.7 weight percent oxygen

during the winter months

The Clean Air Act Amendments also require the use of

reformulated gasoline (RFG) in those areas of the United

States with the most severe ozone pollution Under the Clean

Air Act Amendments and the Energy Policy Act of 1992,

Con-gress enacted legislation requiring the use of alternative fuels

and alternative fuel vehicles Fuels containing high

concen-trations of ethanol or methanol, where oxygenate is the

pri-mary component of the blend, qualify as alternative fuels

E85, a blend of 85 volume percent ethanol and 15 volume

percent hydrocarbons, and M85, a blend of 85 volume

per-cent methanol and 15 volume perper-cent hydrocarbons, may be

used in specially designed vehicles to comply with state and

local alternative fuel programs

An oxygenate is defined under ASTM specifications as

an oxygen-containing, ashless, organic compound, such as

an alcohol or ether, which can be used as a fuel or fuel

sup-plement Agasoline-oxygenate blend is defined as a fuel

con-sisting primarily of gasoline along with a substantial amount

(more than 0.35 mass percent oxygen, or more than 0.15

mass percent oxygen if methanol is the only oxygenate) of

one or more oxygenates

While there are several oxygenates that can be used tomeet federal oxygen requirements in gasoline, ethanol is cur-rently the primary oxygenate used to comply with Clean AirAct requirements While methyl tertiary-butyl ether (MTBE)had been used to meet Clean Air Act requirements, statelegislation banning the use of MTBE in gasoline has virtuallyeliminated its use in the United States Other oxygenates,such as methanol, tertiary-amyl methyl ether (TAME), ethyltertiary-butyl ether (ETBE), and diisopropyl ether (DIPE)have been used in much smaller quantities In the early1980s, methanol/tertiary-butyl alcohol mixtures were blendedwith gasoline on a limited scale When methanol is used as

a blending component, it must be accompanied by a vent (a higher molecular weight alcohol) to help preventphase separation of the methanol and gasoline in the pres-ence of trace amounts of water

co-sol-Oxygenated fuels are subject to a number of federal ulations The U.S Environmental Protection Agency regu-lates the allowable use of oxygenates in unleaded gasolineand is responsible for promulgating regulations and enforc-ing the Renewable Fuels Standard program The Alcohol andTobacco Tax and Trade Bureau (TTB) of the Department ofTreasury regulates the composition of alcohol used for fuel.The Internal Revenue Service (IRS) regulates the characteris-tics of fuels qualifying for special tax treatment

reg-This chapter focuses on ethanol and other oxygenatesfor use as blending components in fuel or for use as highethanol content fuels in spark-ignition engines This chaptersummarizes the significance of the more important physicaland chemical characteristics of these oxygenates and the per-tinent test methods for determining these properties Infor-mation on government regulations and tax incentives foroxygenated fuels is provided ASTM specifications for oxy-genates and other biofuels discussed are:

• ASTM D4806, Specification for Denatured Fuel Ethanolfor Blending with Gasolines for Use as Automotive Spark-Ignition Engine Fuel, covers a denatured fuel ethanol suit-able for blending up to 10 volume percent with gasoline

• ASTM D5798, Specification for Fuel Ethanol Ed85) for Automotive Spark-Ignition Engines, covers afuel blend, nominally 75 to 85 volume percent denaturedfuel ethanol and 25 to 15 additional volume percenthydrocarbons for use in ground vehicles with automotivespark-ignition engines

(Ed75-• ASTM D5797, Specification for Fuel Methanol M70-M85for Automotive Spark-Ignition Engine Fuels, covers afuel blend, nominally 70 to 85 volume percent methanoland 30 to 15 volume percent hydrocarbons for use inground vehicles with automotive spark-ignition engines

1 Herman and Associates, Washington, DC.

2 Chevron Products Company, Richmond, CA.

16

Copyright © 2010 by ASTM International www.astm.org

• ASTM D5983, Specification for Methyl Tertiary-Butyl

Ether (MTBE) for Downstream Blending for Use in

Automotive Spark-Ignition Engine Fuel, covers

require-ments for fuel grade methyltertiary-butyl ether utilized

in commerce, terminal blending, or downstream

blend-ing with fuels for spark-ignition engines

• ASTM D6751, Specification for Biodiesel Fuel Blend

Stock (B100) for Distillate Fuels, covers low-sulfur

bio-diesel (B100) for use as a blend component with bio-diesel

fuel oils as defined by ASTM D975, Specification for

Diesel Fuel Oils

• ASTM D7467, Standard Specification for Diesel Fuel Oil,

Biodiesel Blend (B6 to B20), covers fuel blend grades of

6 to 20 volume percent biodiesel with the remainder

being a light middle or middle distillate diesel fuel,

col-lectively designated as B6 to B20

• ASTM D975, Standard Specification for Diesel Fuel Oils,

covers biodiesel blends containing up to 5 volume

per-cent biodiesel fuel

• ASTM D396, Standard Specification for Fuel Oils, covers

biodiesel blends containing up to 5 volume percent

bio-diesel fuel

Gasoline and gasoline-oxygenate blends are subject to

the limits and test methods contained in ASTM D4814,

Standard Specification for Automotive Spark-Ignition Engine

Fuel This chapter does not address the physical and

chemi-cal characteristics of finished gasoline-oxygenate blends The

properties and significance of gasoline-oxygenate blends are

discussed in the chapter, “Automotive Spark-Ignition Engine

Fuel.” Diesel fuel and diesel fuel-biodiesel fuel blends up to

5 volume percent biodiesel fuel are subject to the limits and

test methods contained in ASTM D975, Standard

Specifica-tion for Diesel Fuel Oils, and ASTM D7467, Standard

Specifi-cation for Diesel Fuel Oil, Biodiesel Blend (B6 to B20) The

properties and significance for these fuels are discussed in

the chapter, “Fuels for Land and Marine Diesel Engines for

Non-Aviation Gas Turbines.” Fuel oils and fuel oil-biodiesel

fuel blends up to 5 volume percent biodiesel fuel are subject

to the limits and test methods contained in ASTM D396

Standard Specification for Fuel Oils The properties and

sig-nificance for these fuels are discussed in the chapter,

“Burner, Heating, and Lighting Fuels.”

GOVERNMENT REGULATIONS

Oxygenated Fuels and Reformulated Gasoline

Section 211(m) of the Clean Air Act Amendments of 1990

requires states with wintertime carbon monoxide (CO)

nonat-tainment areas having design values of 9.5 parts per million

(ppm) CO or more based on 1988 and 1989 data to submit

revisions to their State Implementation Plans (SIPs) to

estab-lish a wintertime oxygenated gasoline program The Act

requires that any gasoline sold or dispensed to the ultimate

consumer in a carbon monoxide nonattainment area during

the regulated time period must contain not less than 2.7

weight percent oxygen A number of areas have been

redesig-nated into attainment for carbon monoxide and are no

lon-ger required to have a wintertime oxygenated gasoline

program At the present time, ten areas have wintertime

oxy-genated fuels programs

The Clean Air Act also requires the use of reformulated

gasoline (RFG) in certain areas in order to reduce vehicle

emissions of toxic and ozone-forming compounds Section

211(k)(l) of the Clean Air Act, as amended, prohibits the sale

of conventional gasoline (gasoline that has not been certified

as reformulated) in the nine largest metropolitan areas withthe most severe summertime ozone levels, as well as otherozone nonattainment areas that opt in to the program.Under the Clean Air Act, RFG was originally required in thefollowing nine areas of the country with the highest levels ofozone: Baltimore, Chicago, Hartford, Houston, Los Angeles,Milwaukee, New York, Philadelphia, and San Diego Anyarea reclassified as a severe ozone nonattainment area isrequired to have reformulated gasoline Subsequent to pas-sage of the Clean Air Act, additional areas in the countywere reclassified as severe ozone nonattainment areas andwere thus required to be a covered area under the federalRFG program Other areas with less severe air pollutionproblems were allowed to opt into the reformulated gasolineprogram

The Clean Air Act established a two-phase program forthe implementation of RFG Federal Phase I RFG require-ments began January 1, 1995, and were in effect untilDecember 31, 1999 Phase II performance standards beganJanuary 1, 2000 Under Phase I, the EPA required reformu-lated gasoline to achieve a 15 percent reduction in volatileorganic emissions and toxic air pollutants During Phase II,the EPA requires a 5.5 % reduction in NOx, as well as fur-ther reductions in volatile organic emissions and toxic airpollutants General requirements (under the 1990 Clean AirAct Amendments as amended by the Energy Policy Act of2005) for federal reformulated gasoline are a maximum 1.0volume percent benzene content, a limit on heavy metals,and not causing an increase in emissions of oxides ofnitrogen

Additional information on federal and state lated gasoline requirements and test methods is provided inASTM Committee D02 Research Report, D02:1347, ResearchReport on Reformulated Spark-Ignition Engine Fuel

reformu-Renewable Fuels Standard

On August 8, 2005, the President signed into law the EnergyPolicy Act of 2005 (P.L 109-58) This legislation made signifi-cant revisions to the federal RFG program, and established aRenewable Fuels Standard (RFS) mandating the use of 4 bil-lion gallons of renewable fuels in the U.S starting in 2006,increasing to 7.5 billion gallons by the year 2012 Other keyprovisions of the Energy Policy Act of 2005 (EPACT 2005)included elimination of the minimum 2.0 weight percentoxygen requirement in RFG, establishment of a credits trad-ing program, consolidation of VOC Control Regions, estab-lishment of small refiner provisions, modifications to themobile source air toxics program and baselines, commin-gling of compliant RFG fuels, and other fuel relatedprovisions

In response to EPACT 2005, the EPA enacted a rule toeliminate the minimum oxygen content requirement forRFG both nationally and in California The rule eliminatingthe oxygen content requirement for Federal RFG areas inCalifornia became effective April 24, 2006 The rule eliminat-ing the oxygen requirement for all other RFG areas becameeffective May 5, 2006

For 2006, EPA adopted the default renewable fuels dard set forth in EPACT 2005 The final rule establishing thecomplete RFS program for 2007 and beyond became effec-tive September 1, 2007 The rule established annual renew-able fuel standards through 2012, defined the responsibilities

stan-of refiners and other fuel producers and importers,

estab-lished a credit trading system and set forth recordkeeping

and reporting requirements Under the RFS regulations, any

party that produces or imports gasoline for use in the U.S is

considered an obligated party and is required to meet the

annual renewable fuels standard through the purchase of

renewable identification numbers (RINs) Qualifying small

refiners and small refineries are exempt from meeting the

renewable fuel requirements through 2010 Gasoline

pro-ducers located in Alaska, and noncontiguous U.S territories

are exempt from the RFS program indefinitely, but may

opt into the program Hawaii opted into the program on

January 1, 2008

On December 19, 2007, the President signed into law “the

Energy Independence and Security Act of 2007” (P.L

110-140) This legislation significantly expanded and increased the

Renewable Fuels Standard established under the Energy

Pol-icy Act of 2005 Section 202 of the Energy Independence and

Security Act of 2007 (EISA) requires the use of 9 billion

gal-lons of renewable fuel in 2008, increasing to 36 billion galgal-lons

by 2022 EISA also establishes targets for cellulosic ethanol

and other advanced biofuels By 2022, 21 billion gallons of the

total renewable fuels requirement must be obtained from

cel-lulosic ethanol and other advanced biofuels Figure 1 shows

the applicable volumes of total renewable fuels required

under the EISA of 2007

The EISA of 2007 establishes annual standards for four

categories of renewable fuel: cellulosic biofuel,

biomass-based diesel, total advanced biofuel, and total renewable

fuel To qualify under any of these categories, a renewable

fuel must meet a certain lifecycle greenhouse gas emission

threshold, unless the fuel is produced in a facility that had

commenced construction prior to enactment of the

legisla-tion The U.S Environmental Protection Agency is charged

with issuing regulations to implement the Renewable Fuel

Standard provisions of EISA 2007 The new regulations will

address how the four standards will be set and how

obli-gated parties will comply with the four standards in addition

to other detailed provisions of the legislation

State Biofuel Mandates

In order to encourage the use of renewable fuels, a number

of states have enacted laws mandating the use of ethanol,biodiesel, and/or other biofuels Certain states require that adesignated percentage of the gasoline and/or diesel pool becomprised of renewable fuel Other states have adopted acontent requirement mandating that each gallon of gasoline

or diesel fuel contain a certain percentage of biofuel At thepresent time, twelve states and one county have adoptedlegislation mandating the use of ethanol, biodiesel, and/ orother renewable fuels Those states are Florida, Hawaii, Iowa,Louisiana, Massachusetts, Minnesota, Missouri, Montana, NewMexico, Oregon, Pennsylvania, and Washington as well as thecounty of Portland, OR

Clean Fleets and Alternative Fuels ProgramThe Clean Air Act Amendments of 1990 created a CleanFleets Program to introduce clean fuel vehicles nationwide

In model-year 1996, automobile manufacturers wererequired to produce 150,000 clean-fueled cars and lighttrucks per year under a California pilot program For modelyears 1999 and thereafter, manufacturers must produce300,000 clean fuel vehicles each year

Beginning in model year 1998, 22 cities classified ashaving serious, severe, and extreme ozone nonattainmentareas plus Denver, Colorado, for carbon monoxide nonat-tainment purchased clean fuel vehicles for their fleets Mar-ginal and moderate ozone nonattainment areas are notrequired to participate, but may elect to do so

The Energy Policy Act of 1992 defines alternative fuels

as natural gas, propane, and blends of alcohol with gasoline

or other fuels containing 85 volume percent or more hol, hydrogen, fuels derived from biomass, and liquid fuelsderived from coal and electricity Vehicles can be flexible-fuel or dual-fuel, but must use alternative fuels within thenonattainment areas

alco-Under the legislation, designated federal, state, and fuelprovider fleets are required to replace their gasoline-pow-ered vehicles with alternative fuel vehicles over time Many

Fig 1

fleets are choosing flexible fuel vehicles (FFVs) that can

operate on 85 volume percent ethanol (E85), gasoline, or

any combination of gasoline and alcohol in the same tank

Private-sector companies that produce alternative fuels,

such as natural gas companies or electric utilities, are

required to introduce alternative fuel vehicles into their fleets

as follows: 30 % in model-year 1996, 50 % in model-year 1997,

70 % in model-year 1998, 90 % in model-year 1999 and

there-after The minimum federal fleet requirements for light-duty

alternative fuel vehicles are as follows: 5,000 in fiscal year

1993, 7,500 in fiscal year 1994, 10,000 in fiscal year 1995, 25

% in fiscal year 1996, 33 % in fiscal year 1997, 50 % in fiscal

year 1998, and 75 % in fiscal year 1999 and thereafter

State governments are required to purchase alternative

fuel vehicles in the following amounts: 10 % in model-year

1996, 15 % in model-year 1997, 25 % in model-year 1998, 50

% in model-year 1999, and 75 % in model-year 2000 and

thereafter

Regulations Governing Oxygenated Fuels

The use of oxygenates in blends with unleaded gasoline is

governed by Section 211 (f) of the Clean Air Act and EPA

Fuel and Fuel Additive Registration regulations at 40 CFR 79

EPA waivers granted under Section 211(f), the “substantially

similar” Interpretive Rule, and compliance with EPA

registra-tion requirements govern the allowable amounts of

oxygen-ates that may be added to unleaded gasoline

Section 211(f)(1)(A) of the Clean Air Act prohibits fuel

or fuel additive manufacturers from introducing into

com-merce, or increasing the concentration in use, of any fuel or

fuel additive for general use in light-duty motor vehicles

that is not substantially similar to any fuel or fuel additive

utilized in the certification of any 1975 or subsequent

model year vehicle or engine under Section 206 of the act

EPA treats a fuel or fuel additive as “substantially similar” if

the following criteria are met:

1 The fuel must contain carbon, hydrogen, and oxygen,

nitrogen, and/or sulfur, exclusively in the form of some

of the following:

a Hydrocarbons;

b Aliphatic ethers;

c Aliphatic alcohols other than methanol;

(i) Up to 0.3 volume percent methanol;

(ii) Up to 2.75 volume percent methanol with an

equal volume of butanol, or higher molecular

weight alcohol;

2 A fuel additive at a concentration of no more than 0.25

weight percent that contributes no more than 15 ppm

sulfur by weight to the fuel The fuel must contain no

more than 2.0 weight percent oxygen, except fuels

con-taining aliphatic ethers and/or alcohols (excluding

meth-anol) must contain no more than 2.7 weight percent

oxygen

3 The fuel must possess, at the time of manufacture, all of

the physical characteristics of an unleaded gasoline as

specified in ASTM Standard D4814-88 for at least one of

the seasonal and geographic volatility classes specified

in the standard

4 The fuel additive must contain only carbon, hydrogen,

and any one or all of the following elements: oxygen,

nitrogen, and/or sulfur

For those fuels or fuel additives that are not

“substantially similar,” the manufacturer may apply for a

waiver of the prohibitions as provided in Section 211 (f) (4)

of the Clean Air Act The applicant must establish that thefuel or fuel additive will not cause or contribute to a failure

of any emission control device or system (over the useful life

of any vehicle in which such device or system is used) Prior

to December 2007, if the EPA administrator did not act togrant or deny an application within 180 days of receipt ofthe waiver application, the waiver was deemed as granted.Under the EISA of 2007, the EPA now is required to grant ordeny an application for a waiver within 270 days of its filing.However, in order to be marketed, fuels receiving awaiver or fuels permitted under the “Substantially Similar”rule must also comply with EPA fuels and fuel additive regis-tration requirements

Under 40 CFR 79, “Registration of Fuels and FuelAdditives,” any manufacturer of motor vehicle gasoline ordiesel fuel, or an additive for use in gasoline or diesel fuel,must register with the Environmental Protection Agencyprior to the proposed introduction into commerce of thefuel or fuel additive On May 27, 1994, under Section 211(b)

of the Clean Air Act, the EPA promulgated a rule addinghealth effects information and testing requirements to theagency’s existing registration program for motor vehicle fuelsand fuel additives

For fuels/fuel additives registered before May 27, 1994,Tier 1 data and evidence of a suitable contractual arrange-ment for completion of Tier 2 requirements were required

to be submitted to EPA by May 27, 1997 Fuels/fuel additivesnot registered as of May 27, 1994, are considered either

“registrable” or “new.” “Registrable” fuels/fuel additives arecompositionally similar to currently registered products ingeneral use and may be marketed upon EPA’s receipt of thebasic registration data “New” fuels/fuel additives must com-plete all testing requirements before registration and intro-duction into commerce

With respect to methanol, before the establishment ofthe health effects testing requirement in 1994, methanol co-solvent combinations were allowed under several waiversand/or the Substantially Similar Interpretive Rule at levels

up to 3.5 weight percent oxygen The health effects testingregulations established separate testing categories for eachoxygenate used at a concentration of 1.5 weight percent oxy-gen or greater

Testing is under way for MTBE, ethanol, ETBE,Tertiarybutyl alcohol (TBA), DIPE, and TAME Any other oxygenate

or combination of oxygenates previously allowed by theInterpretive Rule or waiver, such as a methanol co-solventcombination, is now limited to the baseline category, whichmust contain less than 1.5 weight % oxygen Methanolblends, which contribute greater than 1.5 weight % total oxy-gen to the fuel, may not be marketed unless a health effectstesting program is conducted Because the current potentialfor methanol blends is limited, it is unlikely that any fuelmanufacturer would perform the health effects testing nec-essary for higher usage

Table 1, “EPA Waivers and Substantially Similar Levelsfor Oxygenated Fuels,” summarizes oxygenated fuels granted

a waiver from EPA or permitted under the EPA “SubstantiallySimilar” interpretive rule

Alcohol and Tobacco Tax and Trade BureauThe Alcohol and Tobacco Tax and Trade Bureau (TTB) is thegovernment agency responsible for regulating distilled spirits

TABLE 1—EPA Waivers and Substantially Similar Levels for Oxygenated Fuels

Ethanol must be anhydrous.

Ethanol Additive (Synco 76) Proprietary stabilizer mixed

with anhydrous ethanol and denatured with methyl isobutyl ketone Additive must include

67 % hexanol, 4 % pentanol,

2 % octanol, and 27 % nates derived from the coal liquefaction process

araffi-Waiver granted to Synco 76 Fuel Corporation, 1982

Must be used in 1:20 ratio with ethanol ( 1 = 4 gal stabilizer to 5 gal ethanol added to 45 gal of finished unleaded gasoline Must meet ASTM volatility requirements for time of year and location.

of commingling during storage

or transport, and not fully added.

of 1:1.

Methanol without Cosolvents A Cannot exceed 0.3 % straight

methanol (i.e., without cosolvents)

Substantially Similar Rule, 1981, modified in 1991

Must meet ASTM volatility its for one of ASTM volatility classes.

lim-Methanol with Cosolvents A 2.75 % with equal butanol or

other higher molecular weight alcohols

Substantially Similar Rule 1981, modified in 1991

Must meet ASTM volatility its for one of ASTM volatility classes.

Methanol/Cosolvents A

(Sun Waiver)

5 % methanol, 2.5 % cosolvent alcohols Max 3.7 % oxygen (w)

Waiver granted to Sun Refining and Marketing, 1985

Must meet ASTM volatility limits.

Methanol/Cosolvents A

(Dupont Waiver)

5 % methanol, 2.5 % cosolvent alcohols having a carbon num- ber of 4 or less (i.e., ethanol, propanol, butanol, and/or GTBA)

Waiver granted to E I DuPont

de Nemours and Company,

1985 modified in 1986 and 1987

Must contain one of three specified corrosion inhibitors, must meet ASTM volatility limits.

alcohols with a carbon number

of 8 or less Pentanols, nols, heptanols, and octanols or mixtures are limited to a maxi- mum of 40 % (w)

hexa-Heptanols and octanols are ited to 5 % max (w)

lim-Waiver granted to Texas Methanol Corporation, 1988

Corrosion inhibitor required Must meet ASTM D439-85a, plus maximum temperature for phase separation and alcohol purity.

and alcohol fuel plants (AFPs) The TTB requires that all

ethanol must be denatured in accordance with two specified

formulae in order to render it unfit for human

consump-tion For fuel quality purposes, ASTM limits the allowable

denaturants approved by the TTB for fuel ethanol

[Addi-tional information on denaturants is provided under

“Denatured Fuel Ethanol for Blending with Gasoline.”]

Internal Revenue Service

Effective January 1, 2009, under the Food, Conservation, and

Energy Act of 2008 (P.L.110-246) (2008 Farm Bill), Congress

reduced the maximum allowable denaturant content for

pur-poses of claiming the tax credit from 5 volume percent to

2 volume percent of the volume of alcohol The IRS of the

Department of Treasury is responsible for developing

regula-tions to implement the denaturant provisions of the 2008

Farm Bill In order to provide temporary “safe harbor” and

study the issue further, IRS issued a temporary rule

indicat-ing that IRS will not challenge a claim to a credit or

pay-ment with respect to the volume of denaturant in alcohol

fuel mixtures as long as the added denaturants do not

exceed 2.5 % of the volume of alcohol Final regulations are

under development

FEDERAL TAX INCENTIVES FOR

RENEWABLE FUELS

In order to encourage the use of renewable energy and

alter-native fuels, the federal government has provided a number

of tax incentives for biofuels, including ethanol, biodiesel,

renewable diesel, and cellulosic biofuel Some of the tax

incentives provided by Congress for biofuels include:

• An excise tax credit from the federal excise tax on

gaso-line or income tax credits for ethanol not derived from

petroleum, natural gas, or coal (including peat);

• An excise tax credit from the federal excise tax on diesel

fuel or income tax credits for each gallon of biodiesel

and renewable diesel used by the taxpayer in producing

a qualified biodiesel mixture for sale or use in a trade

or business;

• An excise tax credit for producers of cellulosic biofuel;

• An excise tax exemption from the federal excise tax on

special motor fuels for fuel containing at least 85%

methanol, ethanol, or other alcohol produced from

nat-ural gas; and

• Income tax credits for blenders of alcohol mixtures, users

of straight alcohol fuel, and small ethanol producers

Present law provides a tax credit for alcohol used as fuel

The credit is allowed to those who blend the alcohol and

gas-oline mixture for sale or use in their trade or business

“Alcohol fuel mixtures” containing ethanol are provided a

$0.45 cents per gallon excise tax credit for each gallon of

ethanol used in the mixture Under the 2008 Farm Bill, “H.R

6124 Food, Conservation, and Energy Act of 2008” (P.L

110-246), effective January 1, 2009, the ethanol tax incentive was

reduced from $0.51 cents to $0.45 cents per gallon for

qualify-ing mixtures Under the excise tax credit system, gasoline

refin-ers and marketrefin-ers are required to pay the full rate of tax (18.4

cents per gallon) on the total gasoline-ethanol mixture

(includ-ing the ethanol portion), but are able to claim a $0.45 per

gal-lon tax credit or refund for each galgal-lon of ethanol used in the

mixture The credit is paid on the amount of alcohol added to

the fuel mixture Under present law, the current excise tax

credit for ethanol is in effect until December 31, 2010

The Food, Conservation and Energy Act of 2008, H.R

2419, includes an income tax credit for producers of losic alcohol and other cellulosic biofuels The credit is $1.01per gallon If the cellulosic biofuel is ethanol, this amount isreduced by the amount of credit available for alcohol fuels.Present law provides an excise tax credit for qualifyingbiodiesel mixtures The credit or payment amount is $1.00per gallon A credit is available for each gallon of biodieselused by the taxpayer in producing a qualified biodiesel mix-ture for sale or use in a trade or business A qualified biodie-sel mixture is a mixture of biodiesel and diesel fuel that (1)

cellu-is sold by the taxpayer producing the mixture to any personfor use as a fuel, or (2) is used as a fuel by the taxpayer pro-ducing the mixture The IRS has determined that a renew-able diesel mixture is treated as a biodiesel mixture and thusqualifies for the tax credit allowable for biodiesel Underpresent law, the tax credit for biodiesel mixtures is in effectuntil December 31, 2009

FUEL ETHANOLEthanol has been used in gasoline blends (known as

“gasohol”) in the U.S for many years Under the EPA waiverfor gasohol, a maximum 10 volume percent ethanol may beused While in 1978 ethanol was used as an octane enhancerand gasoline extender, market penetration of gasoline-etha-nol blends has significantly expanded in response to govern-ment programs mandating increased use of renewable fuels.During 2008, the U.S ethanol industry produced 9 billiongallons of ethanol Ethanol blended gasoline now representsapproximately 70 % of the U.S motor fuel market

While the majority of fuel ethanol marketed in the U.S

is used as a blending component in gasoline in tions up to 10 volume percent, ethanol is also being used asfuel, in concentrations as high as 85 volume percent ethanol

concentra-in specially designed flexible fuel vehicles Ethanol is anapproved alternative fuel as defined in the Energy Policy Act

In certain locations throughout the country, ethanol fuels arebeing used in fleets, urban buses and heavy-duty engines.Under current regulations, EPA limits the maximumamount of ethanol that can be added to unleaded gasoline

at 10 volume percent However, due to increased marketpenetration of ethanol in response to government mandates,

it is likely that in the near future a “blend wall” will occur –where by all U.S gasoline will contain the maximumamount of ethanol, i.e., 10 volume percent, currently allowedunder EPA regulations In order to surpass this “blend wall”and enable greater use of renewable fuels, the U.S govern-ment and industry are conducting a major research program

to collect the necessary data to determine whether higherlevel ethanol blends in amounts higher than 10 volume %can be used safely in conventional vehicles, small engine,and marine applications without jeopardizing emissionrequirements and durability

ASTM has adopted two specifications governing theproperties and limits of fuel ethanol:

• ASTM D4806, Specification for Denatured Fuel Ethanolfor Blending with Gasolines for Use as AutomotiveSpark-Ignition Engine Fuel, covers a denatured fuel-grade ethanol that is suitable for blending up to 10 vol-ume percent with gasoline

• ASTM D5798, Specification for Fuel Ethanol (Ed75-Ed85)for Automotive Spark-Ignition Engines, covers a fuelblend, nominally 75 to 85 volume percent denatured fuel

ethanol and 25 to 15 additional volume percent

hydrocar-bons for use in flexible fuel and dedicated E85 fuel

vehicles with automotive spark-ignition engines

Following is a discussion of ASTM specifications and

test methods for fuel ethanol [Note: Blends of ethanol and

gasoline are also governed by the limits and test methods of

ASTM D4814, Specification for Automotive Spark-Ignition

Fuel See the chapter “Automotive Spark-Ignition Engine

Fuel” for a discussion of these limits and test methods.]

Test Methods for Gasoline-Oxygenate Blends

Many of the original test methods used to measure the

prop-erties of gasoline-oxygenate blends were developed for

hydrocarbons, and are not necessarily applicable for

gaso-line-oxygenate blends A new program is under way within

ASTM to review existing test methods and determine their

applicability for biofuels As part of this program, ASTM is

working to modify the scopes and develop precision

state-ments for the test methods specified in D4814, D4806, and

D5798 In certain cases, modifications have already been

made to the scopes of various test methods In other

instan-ces, where no standardized test method currently exists,

(such as a direct test for denaturant content in ethanol), new

test methods may need to be developed

DENATURED FUEL ETHANOL FOR BLENDING

WITH GASOLINE

ASTM D4806, Standard Specification for Denatured Fuel

Ethanol for Blending with Gasolines for Use as Automotive

Spark-Ignition Engine Fuel, establishes limits and test

meth-ods for denatured fuel ethanol This specification covers

nominally anhydrous denatured fuel ethanol intended to be

blended with unleaded or leaded gasolines at 1 to 10 volume

percent for use as an automotive spark-ignition engine fuel

The specified property limits in ASTM D4806 limits are

not designed for blending E85 Denatured fuel ethanol for

blending E85 must conform with the limits and test methods

in D5798, Specification for Fuel Ethanol (Ed75-Ed85) for

Automotive Spark-Ignition Engines

Denaturants

The TTB, formerly the Bureau of Alcohol, Tobacco, and

Fire-arms, under the U.S Department of Treasury, requires that

certain materials must be added to ethanol under a formula

approved by the TTB in order to make the alcohol unfit for

beverage or internal human medicinal use and therefore not

subject to alcohol beverage tax These materials are called

denaturants

Under ASTM D4806, the only denaturants allowed to be

used for fuel ethanol shall be natural gasoline, gasoline

com-ponents, or unleaded gasoline at a minimum concentration

of two parts by volume per 100 parts by volume of fuel

etha-nol The denatured fuel ethanol covered by ASTM D4806

may contain between 1.96 and 5.0 volume percent

denatur-ant As discussed earlier, the IRS is developing new

regula-tions to implement a federal law requiring that for tax

purposes, the maximum allowable denaturant is 2 volume

percent of the total alcohol

The denaturant content is determined by the ratio of

metered denaturant and ethanol volumes at the time of

denaturing Approved ASTM analytical methods do not exist

to determine that the amount of denaturant added during

the denaturing process or contained in the denatured fuel

ethanol are within the appropriate limits allowed by theTTB

One denatured formula specifically designed for fueluse by the TTB is Formula CDA-20 It requires that for every

100 gal of ethanol of not less than 195 proof, a total of 2.0gal of denaturant be added Another fuel alcohol renderedunfit for beverage use and manufactured at an alcohol fuelplant requires the addition of 2 gal or more of materialslisted by the TTB director to each 100 gal of ethanol ASTMdoes not allow certain formulas permitted by federal denatur-ant regulations because they can be harmful to automotiveengines ASTM D4806 does not allow the use of hydrocarbonswith an end boiling point higher than 225
C (437
F) as deter-mined by ASTM D86, Test Method for Distillation of Petro-leum Products at Atmospheric Pressure ASTM D4806prohibits such denaturants because they can adversely affectfuel stability, automotive engines, and fuel systems Prohibiteddenaturants are methanol that does not meet ASTM D1152,Specification for Methanol (Methyl Alcohol), pyrroles, turpen-tine, ketones, and tars (high-molecular weight pyrolysis prod-ucts of fossil or nonfossil vegetable matter)

The California Air Resources Board (ARB) has adoptedadditional restrictions on denaturants ARB regulations limitthe amounts of benzene, aromatics, and olefins present.ASTM D5580, Standard Test Method for Determination ofBenzene, Toluene, Ethylbenzene, p/m-Xylene, o-Xylene, C9and Heavier Aromatics, and Total Aromatics in Finished Gas-oline by Gas Chromatography, is used to determine the ben-zene and aromatics contents of the denaturant ASTMD6550, Standard Test Method for Determination of OlefinContent of Gasolines by Supercritical-Fluid Chromatography,

is used to determine the olefins content of the denaturant.Water Content

The water content of denatured fuel ethanol must be limitedwhen blended with gasoline Blends of fuel ethanol and gaso-line have a limited solvency for water This solvency will varywith the ethanol content, the temperature of the blend, andthe aromatics content of the base gasoline A fuel made byblending 10 volume percent fuel ethanol with a gasoline contain-ing 14 volume percent aromatics and 0.6 mass percent dissolvedwater (about 0.5 volume percent) will separate into a lower alco-hol-rich aqueous phase and an upper hydrocarbon phase ifcooled to about 7
C (45
F) As normal spark-ignition engineswill not run on the aqueous phase material, such a separation

is likely to cause serious operating problems Because somedegree of water contamination is practically unavoidable intransport and handling, and because gasoline-ethanol blendsare hygroscopic, the water content of the denatured fuel etha-nol must be limited when blended with gasoline to reduce therisk of phase separation

ASTM E203, Test Method for Water Using VolumetricKarl Fischer Titration, is generally the only consistently reli-able procedure for the determination of water in denaturedfuel ethanol ASTM E203 includes modifications required

to run the test in the presence of alcohols Because theaddition of denaturants will normally affect specific gravity,specific gravity methods such as ASTM D891, Test Methodsfor Specific Gravity, Apparent, of Liquid Industrial Chemi-cals, and ASTM D3505, Test Method for Density or RelativeDensity of Pure Liquid Chemicals, are generally not suitablefor determining the water content of denatured fuelethanol

Solvent Washed Gum

Solvent washed gum is important because it can contribute

to deposits on the surfaces of carburetors, fuel injectors, and

intake manifolds, ports, valves, and valve guides Solvent

washed gum consists of fuel-insoluble gum The

fuel-insolu-ble portion can clog fuel filters Both types of gum can be

deposited on surfaces when the fuel evaporates

ASTM D381, Test Method for Gum Content in Fuels by

Jet Evaporation, is used to determine solvent washed gum

This test method is used to detect the presence of

high-boiling, heptane-insoluble impurities and measures the

amount of residue remaining after the fuel evaporates and

after a heptane wash is performed However, the precision

statements for ASTM D381 were developed using only data

on hydrocarbons and may not be applicable to denatured

fuel ethanol

pHe

pHe is a measure of the acid strength of alcohol fuels The

pHe of ethanol is important to reduce the risk of fuel

injec-tor failure and engine cylinder wear When the pHe of

etha-nol used as a fuel for automotive spark-ignition engines is

below 6.5, fuel pumps can malfunction as a result of film

forming between the brushes and commutator, fuel injectors

can fail from corrosive wear, and excessive engine cylinder

wear can occur When the pHe is above 9.0, fuel pump

plas-tic parts can fail The adverse effects are less when ethanol

is used at concentrations of 10 volume percent or less in

gasoline

ASTM D6423, Test Method for Determination of pHe of

Ethanol, Denatured Fuel Ethanol, and Fuel Ethanol

(Ed75-Ed85), is used to determine the pHe levels of fuel ethanol

The test method is applicable to fuels containing nominally

70 volume % ethanol or higher, as described in ASTM

D4806, Specification for Denatured Fuel Ethanol for

Blend-ing With Gasolines for Use as Automotive Spark-Ignition

Engine Fuel, and ASTM D5798, Specification for Fuel

Etha-nol (Ed75-Ed85) for Automotive Spark-Ignition Engines The

pHe value will depend somewhat on the fuel blend, the

stir-ring rate, and the time the electrode is in the fuel

Chloride Ion Content

Low concentrations of chloride ions are corrosive to many

metals ASTM D7319, Test Method for Determination of

Total and Potential Sulfate and Inorganic Chloride in Fuel

Ethanol by Direct Injection Suppressed Ion

Chromatogra-phy, or ASTM D7328, Test Method for Determination of

Total and Potential Inorganic Sulfate and Total Inorganic

Chloride in Fuel Ethanol by Ion Chromatography Using

Aqueous Sample Injection, is used to determine inorganic

chloride content in ethanol

Sulfate Content

The presence of small amounts of inorganic sulfates in

dena-tured fuel ethanol under the right conditions can contribute

to turbine meter deposits and the premature plugging of

fuel dispensing pump filters in the fuel distribution system

The sulfates also have been shown to cause fuel injector

sticking, resulting in engine misfiring and poor driveability

in automobiles ASTM D7318, Test Method for Total

Inor-ganic Sulfate in Ethanol by Potentiometric Titration, ASTM

D7319, Test Method for Determination of Total and

Poten-tial Sulfate and Inorganic Chloride in Fuel Ethanol by Direct

Injection Suppressed Ion Chromatography, or ASTM D7328,Test Method for Determination of Total and Potential Inor-ganic Sulfate and Total Inorganic Chloride in Fuel Ethanol

by Ion Chromatography Using Aqueous Sample Injection, isapplicable to determine sulfate content in ethanol

Copper ContentCopper is an active catalyst for the low-temperature oxida-tion of hydrocarbons Experimental work has shown thatcopper concentrations higher than 0.012 mg/kg in commer-cial gasoline may significantly increase the rate of gum for-mation ASTM D1688, Test Methods for Copper in Water,Test Method A, has been modified for determining the cop-per content of denatured fuel ethanol The modification ofTest Method A (atomic absorption, direct) consists of mixingreagent grade ethanol (which may be denatured according

to the TTB Formula 3A or 30) in place of water as the vent or diluent for the preparation of reagents and standardsolutions Because a violent reaction may occur between theacid and the ethanol, use water, as specified, in the acid solu-tion part of the procedure to prepare the stock copper solu-tion Use ethanol for the rinse and final dilution only Theprecision of this modified method has not been determined,but the precision is expected to be similar to the precision

sol-of Test Method A in ASTM D1688

AcidityDenatured fuel ethanol may contain additives such as corro-sion inhibitors and detergents that may affect the titratableacidity (acidity as acetic acid) of the finished fuel ethanol.Very dilute aqueous solutions of low-molecular weightorganic acids such as acetic acid (CH3COOH) are highly cor-rosive to many metals It is necessary to keep such acids at avery low level ASTM D1613, Test Method for Acidity in Vola-tile Solvents and Chemical Intermediates Used in Paint, Var-nish, Lacquer, and Related Products, is used to determinethe acidity of denatured fuel ethanol

AppearanceDenatured fuel ethanol is required to be visibly free of sus-pended or precipitated contaminants (clear and bright) Tur-bidity or evidence of precipitation normally indicates majorcontamination This shall be determined at indoor ambienttemperature unless otherwise agreed upon between the sup-plier and the purchaser

Ethanol PurityThe presence of even small quantities of some organic oxy-gen compounds other than ethanol may adversely affect theproperties of gasoline-ethanol blends ASTM D5501, TestMethod for the Determination of Ethanol Content of Dena-tured Fuel Ethanol by Gas Chromatography, determines theethanol and methanol contents of denatured fuel ethanol.FUEL ETHANOL: ED75-ED85

ASTM D5798, Specification for Fuel Ethanol (Ed75-Ed85) forAutomotive Spark-Ignition Engines, covers a fuel blend, nom-inally 75 to 85 volume percent denatured fuel ethanol and

25 to 15 additional volume percent hydrocarbons for use inground vehicles with automotive spark-ignition enginesdesigned to use it, which are designated as dedicated E85vehicles or as flexible fuel vehicles Fuel ethanol (Ed75-Ed85) is defined as a blend of ethanol and hydrocarbons of

which the measured ethanol portion is nominally 70 to 79

volume percent

Denatured fuel ethanol for blending E85 is required

to meet the limits and test methods of D5798, Specification

for Fuel Ethanol (Ed75-Ed85) for Automotive Spark-Ignition

Engines Since the specified property limits in ASTM D4806

limits are not designed for blending E85, blenders of E85

need to ensure that the final E85 blend conforms with the

requirements of ASTM D5798

While the performance requirements of ASTM D5798

are based on the best technical information available, these

requirements are still under development Certain

perfor-mance limits in ASTM D5798 are likely to change in the

future as improvements in vehicle technology occur and

greater field experience is gained from field use of fuel

etha-nol vehicles

The ethanol content of fuel ethanol (Ed75-Ed85) is a

critical parameter since it affects the capability of the fuel

metering system of dedicated Ed75-Ed85 vehicles to

estab-lish the proper air/fuel ratio for optimum vehicle operation

This is much less of a concern for flexible fuel vehicles than

for dedicated Ed75-Ed85 vehicles Ethanol content may also

affect the lubricating properties of the fuel, water tolerance,

and the ability to meet cold and cool area volatility

require-ments The inclusion of impurities, some denaturants, and

contaminants, can adversely affect the properties and

per-formance of fuel ethanol (Ed75-Ed85) The quantities of

some of these materials are controlled by specified property

limits The limits on water, higher molecular weight alcohols,

and methanol and on types of denaturants as well as

mini-mums on the amount of ethanol and hydrocarbons limit,

but do not prevent, the presence of trace materials ASTM

D5501, Test Method for the Determination of Ethanol

Con-tent of Denatured Fuel Ethanol by Gas Chromatography, is

used to determine ethanol and methanol contents

Vapor Pressure

Denatured fuel ethanol has a low vapor pressure, and the

addition of volatile hydrocarbons to make fuel ethanol

(Ed75-Ed85) is required for adequate cold startability The

addition of hydrocarbons that are too volatile can contribute

to hot fuel handling problems Higher vapor pressures are

required at colder ambient temperatures, while lower

volatil-ity fuels are less prone to hot fuel-handling problems at

higher (summertime) ambient temperatures Excessive vapor

pressure contributes to evaporative emissions

Lower and upper limits on vapor pressure for the three

volatility classes are used to define the acceptable range of

volatile components to ensure adequate vehicle

perform-ance Vapor pressure is varied for seasonal and climatic

changes by providing three vapor pressure classes for fuel

ethanol (Ed75-Ed85) Class 1 encompasses geographic areas

with six-hour tenth percentile minimum ambient

tempera-ture greater than 5
C (41
F) Class 2 encompasses

geo-graphic areas with six-hour tenth percentile minimum

ambient temperature greater than5
C (23
F) but less than

þ 5
C (41
F) Class 3 encompasses geographic areas with

six-hour tenth percentile minimum ambient temperature less

than or equal to5
C (23
F) ASTM D4953, Test Method for

Vapor pressure of Gasoline and Gasoline-Oxygenate Blends

(Dry Method), ASTM D5190, Test Method for Vapor Pressure

of Petroleum Products (Automatic Method), or ASTM D5191,

Test Method for Vapor Pressure of Petroleum Products (Mini

Method), shall be used to determine the vapor pressure ofEd75-Ed85

HydrocarbonsHydrocarbons are deliberately added to provide improvedcold startability and warm-up driveability For cold ambientconditions, increasing the hydrocarbon content improves coldstartability The addition of hydrocarbons also contributes toflame visibility (luminous flame), nonexplosive air-fuel mix-tures in storage tanks (rich mixture vapor space), and denatu-ration (malodorant and taste deterrent) The hydrocarbonportion of the fuel must be unleaded While the composition

of the hydrocarbons added to fuel ethanol is not controlled,the hydrocarbons should be stable, noncorrosive, and be inthe boiling range of spark-ignition engine fuel as specified inSpecification D4814, Standard Specification for Automotive-Spark Ignition Engine Fuel It should have sufficient vaporpressure to meet the requirements of ASTM D5798 ApprovedASTM analytical methods do not exist to determine theamount of hydrocarbon added during the blending process.Acidity

Ed75-Ed85 as well as denatured fuel ethanol may containadditives such as corrosion inhibitors and detergents thatcould affect the titratable acidity (acidity as acetic acid) ofthe fuel [See acidity discussion under “Denatured Fuel Etha-nol for Blending with Gasoline” for additional information.]ASTM D1613, Test Method for Acidity in Volatile Solventsand Chemical Intermediates Used in Paint, Varnish, Lacquer,and Related Products, is used to determine the acidity ofdenatured fuel ethanol

pHeThe pHe of Ed75-Ed85 is important to reduce the risk offuel injector failure and engine cylinder wear [See pHe dis-cussion under “Denatured Fuel Ethanol for Blending withGasoline” for additional information.] The adverse effectsare believed to be greater when ethanol is used at higherconcentrations than in a 10 volume percent blend with gaso-line ASTM D6423, Test Method for Determination of pHe ofEthanol, Denatured Fuel Ethanol, and Fuel Ethanol (Ed75-Ed85), is used to determine the pHe levels of fuel ethanol.The test method is applicable to fuels containing nominally

70 volume percent ethanol or higher, as described in ASTMD4806, Specification for Denatured Fuel Ethanol for Blend-ing With Gasolines for Use as Automotive Spark-IgnitionEngine Fuel, and ASTM D5798, Specification for Fuel Etha-nol (Ed75-Ed85) for Automotive Spark-Ignition Engines.Gum Content, Solvent Washed and UnwashedSolvent washed gum can contribute to deposits on the sur-face of carburetors, fuel injectors, and intake manifolds,ports, valves, and valve guides The impact of solvent washedgum on engines that can operate on fuel ethanol (Ed75-Ed85) has not been fully established but is based on limitedexperience gained with M70-M85 fuels in field tests and fromhistoric gasoline limits Performance effects depend onwhere the deposits form and the amount of deposit The testfor solvent washed gum content measures the amount of res-idue after the evaporation of the fuel and following a hep-tane wash The heptane wash removes the heptane-soluble,nonvolatile material, such as additives, carrier oils used withthe additives, and diesel fuel

Unwashed gum content consists of fuel-insoluble and

fuel-soluble gum The fuel-insoluble portion can clog fuel

fil-ters Both can be deposited on surfaces when the fuel

evapo-rates The difference between the unwashed and solvent

washed gum content values can be used to assess the

pres-ence and amount of nonvolatile material in the fuel

Addi-tional analytical testing is required to determine if the

material is additive, carrier oil, diesel fuel, or other

The unwashed gum content limit is intended to limit

high-boiling contaminants, like diesel fuel, that can affect

engine performance, yet allow the use of appropriate levels

of deposit control additives with carrier fluids in fuel ethanol

(Ed75-Ed85) ASTM D381, Test Method for Gum Content in

Fuels by Jet Evaporation, is used to determine unwashed and

solvent washed gum Because the precision statements for

ASTM D381 were developed using only data on

hydrocar-bons, they may not be applicable to fuel ethanol (Ed75-Ed85)

Ionic Chloride

Ionic (inorganic) chloride is corrosive to many metals, and it

is desirable to minimize ionic chlorine compounds in fuel

ethanol (Ed75-Ed85) An inorganic chloride limit of a

maxi-mum 1 mg/kg has been found to be adequate in protecting

fuel system components ASTM D7319, Test Method for

Determination of Total and Potential Sulfate and Inorganic

Chloride in Fuel Ethanol by Direct Injection Suppressed Ion

Chromatography or ASTM D7328, Test Method for

Determi-nation of Total and Potential Inorganic Sulfate and Total

Inorganic Chloride in Fuel Ethanol by Ion Chromatography

Using Aqueous Sample Injection, determines inorganic

chlo-ride content in Ed75-Ed85

Sulfur

The limit on sulfur content is included to protect against

engine wear, deterioration of engine oil, corrosion of

exhaust system parts, and exhaust catalyst deactivation

Sul-fur content can be determined using ASTM D1266, Test

Method for Sulfur in Petroleum Products (Lamp Method),

ASTM D2622, Test Method for Sulfur in Petroleum Products

by Wavelength Dispersive X-Ray Fluorescence Spectrometry,

ASTM D3120, Test Method for Trace Quantities of Sulfur in

Light Liquid Petroleum Hydrocarbons by Oxidative

Micro-coulometry, or ASTM D5453, Test Method for Determination

of Total Sulfur in Light Hydrocarbons, Motor Fuels and Oil

by Ultraviolet Fluorescence With ASTM D2622, prepare the

calibration standards using ethanol (reagent grade) as the

solvent to prevent errors caused by large differences in

car-bon/hydrogen ratios

Lead

Most vehicles equipped to operate on fuel ethanol

(Ed75-Ed85) are equipped with exhaust catalysts that control

emis-sions of aldehydes (formaldehyde and acetaldehyde) as well

as regulated emissions Lead compounds deactivate the

cata-lyst and are limited to trace amounts ASTM D5059, Test

Methods for Lead in Gasoline by X-Ray Spectroscopy, is

used to determine lead content

Phosphorus

Phosphorus deactivates exhaust catalysts and is limited by

federal regulations to trace amounts ASTM D3231, Test

Method for Phosphorus in Gasoline, is used to determine

phosphorus levels

WaterThe solubility of hydrocarbons in fuel ethanol (Ed75-Ed85)decreases with lowering temperature and increasing watercontent Separation of the hydrocarbon from the fuel willadversely affect cold starting, driveability, and denaturing.Water may affect the calibration of some types of composi-tion sensors of flexible-fuel vehicles Water also reduces theenergy content of the fuel and thus adversely affects fueleconomy and power Because some degree of water contam-ination is unavoidable in transport and handling, andbecause fuel ethanol (Ed75-Ed85) is miscible with water, thewater content of fuel ethanol (Ed75-Ed85) is limited toreduce the potential for problems ASTM E203, Test Methodfor Water Using Karl Fischer Titration or E1064, TestMethod for Water in Organic Liquids by Coulometric KarlFischer Titration, is a suitable test method for determiningwater content

CopperCopper is an active catalyst for low-temperature oxidation ofhydrocarbons Experimental work has shown that copperconcentrations higher than 0.012 mg/kg in commercial gaso-lines may significantly increase the rate of gum formation.ASTM D1688, Test Methods for Copper in Water, is used todetermine copper content

FUEL METHANOL: M70-M85ASTM D5797, Standard Specification for Fuel MethanolM70-M85 for Automotive Spark-Ignition Engines, covers afuel blend, nominally 70 to 85 volume percent methanol and

30 to 15 volume percent hydrocarbons for use in groundvehicles with automotive spark-ignition engines.Fuel metha-nol (M70-M85) is defined as a blend of methanol and hydro-carbons of which the methanol portion is nominally 70 to

85 volume percent

MethanolThe methanol content of M70-M85 is a crucial parameter,

as it affects the capability of the fuel metering system ofthe vehicle to establish the proper air/fuel ratio for opti-mum vehicle operation This is much less of a concern forflexible-fuel vehicles (FFVs) than for dedicated M70-M85vehicles Methanol content affects the lubrication proper-ties of the fuel and affects the water tolerance of the M70-M85 The inclusion of impurities and contaminants, exceptfor deliberately added hydrocarbons or additives, canimpact adversely on the properties and performance offuel methanol (M70-M85) as an automotive spark-ignitionengine fuel The quantities of some of these materials arelimited by specified property limits Trace amounts ofunspecified materials including higher alcohols, methyl for-mate, acetone, and dimethyl ether can be present The maxi-mum limit on water, the maximum limit on higher alcohols,and minimum and maximum limits on hydrocarbon/aliphaticether content control the amount of some impurities andcontaminants

Test Method for Determination of Methanol in FuelMethanol (M70-M85) for Automotive Spark-Ignition Engines,which appears in Annex A1 of ASTM D5797, provides a pro-cedure for measuring methanol content by gas chromatogra-phy for fuels containing 70 to 95 volume percent methanol.However, the precision of this test method may not beadequate

Hydrocarbons are deliberately added to provide improved

cold startability and warm-up driveability The addition of

hydrocarbons also contributes to flame visibility (luminous

flame), nonexplosive air/fuel mixtures in storage tanks (rich

mixture vapor space), and denaturation (malodorant and

taste deterrent) The hydrocarbon portion of the fuel must

be unleaded While the composition of the hydrocarbons

added to the fuel methanol is not controlled, the

hydrocar-bons should be stable, noncorrosive, and be in the boiling

range of spark-ignition engine fuel provided in ASTM D4814,

Specification for Automotive Spark-Ignition Engine Fuel

ASTM D4815, Test Method for Determination of MTBE,

ETBE, TAME, DIPE, tertiary-Amyl Alcohol and C1to C4

Alco-hols in Gasoline by Gas Chromatography, with

modifica-tions, may be used to determine higher alcohols, MTBE, and

other ethers Water may also be determined if the gas

chro-matograph is equipped with a thermal conductivity detector

As an alternative, ASTM E203, Test Method for Water Using

Karl Fischer Titration, can be used for measurement of

water The concentration of methanol, other alcohols, and

water can be added, and the sum subtracted from 100 to

provide an estimate of the percent of hydrocarbons/aliphatic

ethers The precision of such a technique is not known An

alternative test method, Test Method for Determination of

Hydrocarbon/Aliphatic Ether Content of Fuel Methanol

(M70-M85) for Spark-Ignition Engines, is under development

and appears in Annex A2 of ASTM D5797 Its reported

preci-sion is poor

Vapor Pressure

Vapor pressure is varied for seasonal and climatic changes

by providing three vapor pressure classes for M70-M85 The

addition of volatile hydrocarbons improves cold

startabil-ity The addition of too many volatile hydrocarbons can

cause hot fuel-handling problems When blending with

gas-oline during the wintertime, higher hydrocarbon content

may be necessary to obtain required volatility Higher

vapor pressures are required in the wintertime for cold

starting, and lower vapor pressures are needed in the

sum-mertime to prevent hot fuel handling problems Excessive

vapor pressure for a given ambient condition can

contrib-ute to evaporative emissions Lower and upper limits on

vapor pressure for three volatility classes are used to define

the acceptable range of the volatile components to ensure

proper vehicle performance Three vapor pressure classes

of fuel are provided to satisfy vehicle performance

require-ments under different climatic conditions The schedule for

seasonal and geographical distribution indicates the

appro-priate vapor pressure class for each month in all areas of

the United States based on altitude and expected air

temperatures

ASTM D4953, Test Method for Vapor Pressure of

Gaso-line and GasoGaso-line-Oxygenate Blends (Dry Method), ASTM

D5190, Test Method for Vapor Pressure of Petroleum

Prod-ucts (Automatic Method), or ASTM D5191, Test Method for

Vapor Pressure of Petroleum Products (Mini Method), shall

be used to determine the vapor pressure of M70-M85

Luminosity

When pure methanol burns, it produces a blue, smokeless,

nonluminous flame that is nearly invisible in daylight

Thus, it is difficult to know when a fire exists and to fight

such a fire A desirable property for M70-M85 fuel is that itmaintains a clearly visible flame throughout the duration

of a burn It would be hazardous for the visible flame todisappear before the fire was extinguished To make amethanol flame visible, materials such as aromatic hydro-carbons are added to methanol In general, it has beenestablished that unleaded gasoline having greater than 30volume percent aromatics content when used as the hydro-carbon portion of M70-M85 will result in an M70-M85 fuelthat will meet a requirement of a clearly visible flamethroughout most of a burn However, luminosity perform-ance is dependent on the types of aromatics present in thehydrocarbon portion

Appendix X2 of ASTM D5797, Test Method for ity of Fuel Methanol (M70-M85) for Automotive Spark-Igni-tion Engines, covers a procedure to determine if a fuelmethanol (M70-M85) composition produces a luminous flamethroughout the duration of a burn by comparing its luminos-ity performance under controlled conditions to that of etha-nol This test method is not adequate for use in its presentform and is provided for information only

Luminos-AcidityVery dilute aqueous solutions of low-molecular-weightorganic acids such as formic acid are highly corrosive tomany metals It is necessary to keep such acids at a very lowlevel ASTM D1613, Test Method for Acidity in Volatile Sol-vents and Chemical Intermediates Used in Paint, Varnish,Lacquer, and Related Products, shall be used to determineacidity

Gum Content, Solvent Washed and UnwashedThe test for solvent washed gum content measures theamount of residue after evaporation of the fuel and follow-ing a heptane wash The heptane wash removes the heptane-soluble, nonvolatile material such as additives, carrier oilsused with additives, and diesel fuels Unwashed gum consists

of fuel-insoluble gum and fuel-soluble gum The fuel-insolubleportion can clog fuel filters Both can be deposited on surfa-ces when the fuel evaporates

Solvent washed gum content can contribute to deposits

on the surfaces of carburetors, fuel injectors, and intake folds, ports, valves, and valve guides The impact of solvent-washed gum on engines operating on fuel methanol (M70-M85) has not been fully established Performance effectsdepend on where the deposits form and the amount ofdeposit

mani-The difference between the unwashed and solventwashed gum content values can be used to assess the pres-ence and amount of nonvolatile soluble material in the fuel.Additional analytical testing is required to determine if thematerial is an additive, carrier fluid, diesel fuel, or other Theunwashed gum content limit is intended to limit high-boilingcontaminants, like diesel fuel, that can affect engine perfor-mance, yet allow the proper dosage of deposit-control addi-tives with carrier oils normally added to the hydrocarbonportion of the fuel methanol (M70-M85)

ASTM D381, Test Method for Gum Content in Fuels byJet Evaporation, is used for determining unwashed and sol-vent washed gum However, because the precision state-ments for ASTM D381 were developed using only data onhydrocarbons, this test method may not be applicable tofuel methanol (M70-M85)

Ionic Chloride

Ionic (inorganic) chloride is corrosive to many metals, and it

is desirable to minimize ionic chlorine compounds in fuel

methanol (M70-M85) An inorganic chloride limit of a

maxi-mum 1 mg/kg has been found to be inadequate in

protect-ing some fuel system components ASTM D7319, Test

Method for Determination of Total and Potential Sulfate and

Inorganic Chloride in Fuel Ethanol by Direct Injection

Sup-pressed Ion Chromatography or ASTM D7328, Test Method

for Determination of Total and Potential Inorganic Sulfate

and Total Inorganic Chloride in Fuel Ethanol by Ion

Chro-matography Using Aqueous Sample Injection, is used to

determine inorganic chloride content in M75-M85

Lead

Most vehicles equipped to operate on fuel methanol

(M70-M85) are equipped with exhaust catalysts that control

emis-sions of aldehydes (formaldehyde and acetaldehyde) as well

as regulated emissions Lead compounds deactivate the

cata-lysts and are limited to trace amounts to prevent this

prob-lem ASTM D5059, Test Methods for Lead in Gasoline by

X-Ray Spectroscopy, is used to determine lead content

How-ever, when using this test method, prepare the calibration

standards using methanol (reagent grade) as the solvent to

prevent errors caused by large differences in

carbon-hydro-gen ratios

Phosphorus

Phosphorus deactivates exhaust catalysts and is limited to

trace amounts ASTM D3231, Test Method for Phosphorus in

Gasoline is used to determine the presence of phosphorus

Water

The solubility of hydrocarbons in fuel methanol decreases

with lowering temperature and increasing water content

Separation of the hydrocarbon from the fuel will adversely

affect cold starting and driveability, luminosity, and

taste-deterrence Water may affect the calibration of some types

of composition sensors of flexible-fuel vehicles Water also

reduces the energy content of the fuel and thus adversely

affects fuel economy and power Because some degree of

water contamination is practically unavoidable in transport

and handling, and because fuel methanol is miscible with

water, the water content of fuel methanol is limited to

reduce the potential for problems ASTM E203, Test Method

for Water Using Karl Fischer Titration, is a suitable test

method for determining water content of fuel methanol

(M70-M85)

Sulfur

The limit on sulfur content is included to protect against

engine wear, deterioration of engine oil, corrosion of exhaust

system parts, and exhaust catalyst deactivation Sulfur content

can be determined using ASTM D1266, Test Method for

Sul-fur in Petroleum Products (Lamp Method), ASTM D2622, Test

Method for Sulfur in Petroleum Products by Wavelength

Dis-persive X-Ray Fluorescence Spectrometry, ASTM D3120, Test

Method for Trace Quantities of Sulfur in Light Liquid

Petro-leum Hydrocarbons by Oxidative Microcoulometry, or ASTM

D5453, Test Method for Determination of Total Sulfur in

Light Hydrocarbons, Motor Fuels and Oil by Ultraviolet

Fluo-rescence For ASTM D2622, the calibration standards should

be prepared using methanol (reagent grade) as the solvent to

prevent errors caused by large differences in carbon/hydrogenratios

METHYL TERTIARY-BUTYL ETHER FOR BLENDING WITH GASOLINE

ASTM D5983, Specification for Methyl Tertiary-Butyl Ether(MTBE) for Downstream Blending for Use in AutomotiveSpark-Ignition Engine Fuel, covers requirements for fuelgrade MTBE utilized in commerce, terminal blending, ordownstream blending with fuels for spark-ignition engines.MTBE may be used as a blending component for auto-motive spark-ignition engine fuel to meet the oxygenaterequirements of clean air programs or improve the anti-knock quality of certain types of fuels EPA regulations gov-ern the allowable amounts of MTBE and other oxygenatesthat may be added to unleaded gasoline MTBE is also sub-ject to various state regulations that may ban or restrict theuse of MTBE in gasoline

AppearanceSuspended materials, sediments, or contaminants in theMTBE, which cause a cloudy or colored appearance, mayadversely affect the performance of the finished fuel blend

in automotive spark-ignition engines In addition, a cloudy

or colored appearance may indicate excessive water or tamination by materials not directly measured under this spec-ification Appearance should be clear and bright ASTMD4176, Test Method for Free Water and Particulate Contami-nation in Distillate Fuels (Visual Inspection Procedures), Proce-dure 1, shall be used for determining appearance

con-Methyl Tertiary-Butyl Ether PurityThe MTBE minimum purity level limits the quantities of con-taminants A minimum MTBE content of 95.0 mass percenthas been established ASTM Test Method D5441, TestMethod for Analysis of Methyl Tertiary-Butyl Ether (MTBE)

by Gas Chromatography, is used to measure MTBE content.Sulfur

Sulfur and sulfur-containing compounds contribute toengine wear, deterioration of engine oil, exhaust catalystdeactivation, and corrosion of exhaust system parts inspark-ignition engine systems The limit on sulfur isincluded to ensure that the finished blend of fuel is not det-rimental to these systems ASTM D4045, Test Method forSulfur in Petroleum Products by Hydrogenolysis and Rateo-metric Colorimetry, may be used to determine sulfur content.However, the sample may require dilution with a sulfur-freediluent

Solvent Washed Gum ContentThe test for solvent washed gum content measures theamount of residue after evaporation of the fuel and follow-ing a heptane wash The heptane wash removes the heptane-soluble, nonvolatile material such as additives, carrier oilsused with additives, and diesel fuels Solvent washed gumconsists of fuel-insoluble gum The fuel-insoluble portion canclog fuel filters Both can be deposited on surfaces when thefuel evaporates The solvent washed gum content test mayalso indicate contamination of the MTBE during shippingand storage The limit is included to ensure that finishedblends of gasoline do not contain excess solvent washedgum and handling contamination is minimized

Solvent washed gum can contribute to deposits on the

surfaces of carburetors, fuel injectors, and intake manifolds,

ports, valves, and valve guides The impact of solvent washed

gum on malfunctions of modern engines is not well

estab-lished, and the current limit has been assumed from the

his-toric gasoline limit rather than from any recent correlative

work Performance effects depend on where the deposits form

and the amount of deposit ASTM D381, Test Method for Gum

Content in Fuels by Jet Evaporation, is used to determine

sol-vent washed gum However, because the precision statements

for this test method were developed using only data on

hydro-carbons, this test method may not be applicable to MTBE

Copper Strip Corrosion

The limit for copper strip corrosion is included to ensure

that the MTBE does not contribute to copper corrosion

Fuels must pass the copper strip corrosion test to minimize

corrosion in fuel systems due to sulfur compounds in the

fuel ASTM D130, Test Method for Detection of Copper

Cor-rosion from Petroleum Products by the Copper Strip Tarnish

Test, is used to measure copper corrosion

Methanol Content

Methanol content in MTBE is limited to a maximum 0.5 mass

percent Methanol is one of the reactants in the production

of MTBE and is a potential contaminant Methanol

contrib-utes to vapor pressure increase and poorer water tolerance

of finished fuel blends Also, the methanol content of

unleaded fuel is limited by EPA regulations ASTM D5441,

Test Method for Analysis of Methyl Tertiary-Butyl Ether

(MTBE) by Gas Chromatography, may be used to measure

the mass percent of methanol

Water Content

Blends of MTBE and hydrocarbon gasoline have a limited

sol-vency for water This solsol-vency will vary with the chemical

com-position, temperature, and MTBE content of the fuel Excess

water (which may be soluble in the MTBE) may not be soluble

in the gasoline-MTBE blend and could result in a hazy fuel that

does not meet the clear and bright requirement of

Specifica-tion D4814 The water content of MTBE used for blending

with hydrocarbon gasoline is limited to reduce the risk of haze

formation ASTM E203, Test Method for Water Using

Volumet-ric Karl Fischer Titration, or ASTM E1064, Test Method for

Water in Organic Liquids by Coulometric Karl Fischer

Titra-tion, is used to determine the water content of MTBE

Vapor Pressure

The vapor pressure of a finished fuel blend must be high

enough to ensure ease of engine starting Excessive vapor

pres-sure, however, may contribute to vapor lock or high

evapora-tive emissions and running losses The vapor pressure of MTBE

is controlled to prevent adversely affecting the vapor pressure

of the finished blend The EPA regulates the summertime vapor

pressure of finished MTBE fuel blends In addition, vapor

pres-sure exceeding the limits may indicate contamination by a light

hydrocarbon ASTM D4953, Test Method for Vapor Pressure of

Gasoline and Gasoline-Oxygenate Blends (Dry Method), is used

to determine the vapor pressure of MTBE

BIODIESEL FUEL

ASTM D6751, Specification for Biodiesel Fuel Blend Stock

(B100) for Distillate Fuels, covers low-sulfur biodiesel (B100),

for use as a blend component with diesel fuel oils as defined

by ASTM D975, Specification for Diesel Fuel Oils, and byASTM D7467, Standard Specification for Diesel Fuel Oil.Biodiesel, designated B100, is defined as a fuel com-prised of mono-alkyl esters of long chain fatty acids derivedfrom vegetable oils or animal fats.Diesel fuel is defined as alight or middle petroleum distillate fuel A biodiesel blend isdefined as a blend of biodiesel fuel with petroleum-baseddiesel fuel

Biodiesel is typically produced by a reaction of a ble oil or animal fat with an alcohol such as methanol orethanol in the presence of a catalyst to yield mono-alkylesters and glycerin, which is removed Biodiesel derivesapproximately 10 % of its mass from the reacted alcohol.The alcohol used in the reaction may or may not come fromrenewable resources Biodiesel has been generally blended

vegeta-in the United States vegeta-in concentrations of 5 volume percent(B5) and 20 volume percent biodiesel (B20)

Following is a discussion of the major physical andchemical properties of biodiesel

Flash PointThe flash point for biodiesel is used as the mechanism tolimit the level of unreacted alcohol remaining in the fin-ished fuel The flash point is also of importance in connec-tion with legal requirements and safety precautions involved

in fuel handling and storage and are normally specified tomeet insurance and fire regulations Typical values are over

160
C The limit for biodiesel flash point has been set

at 130
C minimum to ensure an actual value of 100
Cminimum

ASTM D93, Test Methods for Flash Point by Martens Closed Cup Tester, can be used except where othermethods are prescribed by law ASTM D3828, Test Methodsfor Flash Point by Small Scale Closed Tester, or ASTMD6450, Standard Test Method for Flash Point by Continu-ously Closed Cup (CCCFP) Tester, can also be used How-ever, the precision and bias of ASTM D3828 and ASTMD6450 with biodiesel is not known and is currently underinvestigation ASTM D93 shall be the referee method.Viscosity

Pensky-Minimum viscosity levels are important to protect againstpower loss due to fuel injection pump and injector leakage.Maximum viscosity levels are limited by engine design andsize and by the characteristics of the fuel injection system.The upper limit of 6.0 mm2/s at 40
C for biodiesel viscosity

is higher than the maximum allowable viscosity in cation D975 Grade 2-D and 2-D low sulfur (4.1 mm/s at

Specifi-40
C) Blending biodiesel with diesel fuel close to its upperlimit could result in a viscosity level exceeding ASTM D975,Specification for Diesel Fuel Oils ASTM D445, Test Methodfor Kinematic Viscosity of Transparent and Opaque Liquids(and the Calculation of Dynamic Viscosity), is used to deter-mine viscosity

Sulfated AshAsh-forming materials may be present in biodiesel as abra-sive solids, soluble metallic soaps, and unremoved catalysts.Abrasive solids and unremoved catalysts can contribute tofuel injector, fuel pump, piston, and ring wear, as well asengine deposits Soluble metallic soaps have little effect onwear but may contribute to filter plugging and engine

deposits Use ASTM D874, Test Method for Sulfated Ash

from Lubricating Oils and Additives, for determining

sulfated ash

Sulfur

The effect of sulfur content on engine cylinder wear and

deposits appears to vary considerably in importance and

depends largely on operating conditions Fuel sulfur can

also affect emissions control systems performance, and

vari-ous limits on sulfur have been imposed for environmental

reasons Most B100 contains less than 5 ppm sulfur Some

biodiesel produced from used cooking oils has been found

to contain slightly higher levels of sulfur (15 to 30 ppm)

ASTM D5453, Test Method for Determination of Total

Sulfur in Light Hydrocarbons, Spark Ignition Engine Fuel,

Diesel Engine Fuel and Engine Oils by Ultraviolet

Fluores-cence, can be used for determining sulfur content Other test

methods may also be suitable for determining up to 0.05 %

sulfur in biodiesel fuels such as ASTM D1266, Test Method

for Sulfur in Petroleum Products (Lamp Method), ASTM

D2622, Test Method for Sulfur in Petroleum Products by

Wavelength Dispersive X-Ray Fluorescence Spectrometry,

ASTM D3120, Test Method for Trace Quantities of Sulfur in

Light Liquid Petroleum Hydrocarbons by Oxidative

Micro-coulometry, and ASTM D4294, Test Method for Sulfur in

Petroleum Products by Energy-Dispersive X-Ray

Fluores-cence Spectroscopy However, these test methods may

pro-vide falsely high results, and their precision and bias with

biodiesel is not known ASTM D5453 shall be the referee test

method

Copper Strip Corrosion

This test serves as a measure of possible difficulties with

cop-per and brass or bronze parts of the fuel system The presence

of acids or sulfur-containing compounds can tarnish the

cop-per strip, thus indicating the possibility for corrosion ASTM

D130, Test Method for Detection of Copper Corrosion from

Petroleum Products by the Copper Strip Tarnish Test, 3-h test

at 50
C, shall be used for determining copper strip corrosion

Cetane Number

Cetane number is a measure of the ignition quality of the

fuel and influences white smoke and combustion roughness

in some engines The cetane number requirements depend

on engine design, size, nature of speed and load variations,

and on starting and atmospheric conditions

ASTM D613, Test Method for Cetane Number of Diesel

Fuel Oil, shall be used for determining cetane number ASTM

D6890, Test Method for Determination of Ignition Delay and

Derived Cetane Number (DCN) of Diesel Fuel Oils by

Com-bustion in a Constant Volume Chamber may also be used

ASTM D976, Test Methods for Calculated Cetane Index of

Dis-tillate Fuels, and ASTM D4737, Test Method for Calculated

Cetane Index by Four Variable Equation, should not be used

to calculate the cetane number of biodiesel or biodiesel

blends, since these test methods may yield falsely low results

Cloud Point

Cloud point is of importance since it defines the

tempera-ture at which a cloud or haze of crystals appears in the fuel

under prescribed test conditions Biodiesel generally has a

higher cloud point than petroleum-based diesel To ensure

trouble-free operation in cold climates, the cloud point of

biodiesel and its impact on cold flow properties of the finalblend should be taken into account

ASTM D2500, Test Method for Cloud Point of PetroleumOils, can be used for determining cloud point ASTM D3117,Test Method for Wax Appearance Point of Distillate Fuels,may also be used because the two test methods are closelyrelated ASTM D5773, Test Method for Cloud Point of Petro-leum Products (Constant Cooling Rate Method), may also beused ASTM D2500 shall be the referee test method How-ever, the precision and bias of these test methods for biodie-sel are not known and are currently under investigation.Cold Soak Filterability

Some substances that are soluble or appear to be soluble inbiodiesel at room temperature will, upon cooling at tempera-tures above the cloud point or standing at room tempera-ture for extended periods, come out of solution Thesesubstances can cause filter plugging ASTM D7501 StandardTest Method for Determination of Fuel Filter BlockingPotential of Biodiesel (B100) Blend Stock by Cold Soak Fil-tration Test (CSFT), provides an accelerated means of assess-ing the propensity for these substances to plug filters.Carbon Residue

Carbon residue gives a measure of the carbon-depositing dencies of a fuel oil While not directly correlating withengine deposits, this property is considered an approxima-tion Although biodiesel is in the distillate boiling range, mostbiodiesel boils at approximately a constant temperature and

ten-it is difficult to leave a 10 % residual upon distillation.ASTM D4530, Test Method for Determination of CarbonResidue (Micro Method), can be used for determining carbonresidue The sample is first distilled to remove 90 volume per-cent The remaining bottoms are subjected to the test procedure.The results are reported as the percentage carbon residue on

10 % distillation residue ASTM D189, Test Method for son Carbon Residue of Petroleum Products, or ASTM D524, TestMethod for Ramsbottom Carbon Residue of Petroleum Prod-ucts, may also be used ASTM D4530 shall be the referee method.Acid Number

Conrad-Acid number is used to determine the level of free fatty acids

or processing acids that may be present in biodiesel Biodieselwith a high acid number has been shown to increase fuel sys-tem deposits and may increase the likelihood for corrosion.Acid number measures a different phenomenon for biodieselthan petroleum-based diesel The acid number for biodieselmeasures free fatty acids or degradation by-products notfound in petroleum-based diesel Increased recycle tempera-tures in new fuel system designs may accelerate fuel degrada-tion that could result in high acid values and increased filterplugging potential ASTM D664, Test Method for Acid Num-ber of Petroleum Products by Potentiometric Titration, can beused for determining acid number ASTM D3242, TestMethod for Acidity in Aviation Turbine Fuel, or ASTM D974,Test Method for Acid and Base Number by Color-IndicatorTitration, may also be used ASTM D664 shall be used as thereferee test method

Free GlycerinFree glycerin is a measure of the amount of glycerin remain-ing in the biodiesel after processing High levels of free glyc-erin can cause injector deposits, as well as clogged fuel

systems, and result in a buildup of free glycerin in the bottom

of storage and fuel systems ASTM D6584, Test Method for

Determination of Free and Total Glycerin in B100 Biodiesel

Methyl Esters by Gas Chromatography, is used to determine

free glycerin

Total Glycerin

Total glycerin is the sum of the free glycerin and the

glyc-erin portion of any unreacted or partially reacted oil or fat

Low levels of total glycerin ensure that high conversion of

the oil or fat into its mono-alkyl esters has taken place High

levels of mono-, di-, and triglycerides can cause injector

deposits and may adversely affect cold weather operation

and filter plugging ASTM D6584, Test Method for

Determi-nation of Free and Total Glycerin in B100 Biodiesel Methyl

Esters by Gas Chromatography, determines total glycerin

Calcium and Magnesium

Calcium and magnesium may be present in biodiesel as

abra-sive solids or soluble metallic soaps Abraabra-sive solids can

contrib-ute to injector, fuel pump, piston, and ring wear, as well as to

engine deposits Soluble metallic soaps have little effect on

wear, but they may contribute to filter plugging and engine

deposits High levels of calcium and magnesium compounds

may also be collected in exhaust particulate removal devices,

are not typically removed during passive or active regeneration,

and can create increased back pressure and reduced time to

service maintenance There is no standard ASTM test method

available, but Test Method EU14538, Fat and Oil Derivatives—

Fatty Acid Methyl Esters (FAME)—Determination of Ca, K, Mg

and Na Content by Optical Emission Spectral Analysis with

Inductively Coupled Plasma (ICP OES) can be used

Water and Sediment

Contamination by water and particulates can adversely affect

the performance of fuel filters and fuel injectors ASTM D2709,

Test Method for Water and Sediment in Middle Distillate Fuels

by Centrifuge, is the preferred test method ASTM D1796, Test

Method for Water and Sediment in Fuel Oils by the Centrifuge

Method (Laboratory Procedure), may also be used

Phosphorus Content

Phosphorus levels must be kept low, since the presence of

phosphorus can damage catalytic converters used in

emis-sion control systems Complying with a phosphorus limit of

10 ppm maximum should not be a problem, since most

bio-diesel produced in the United States has a phosphorus

con-tent below 1 ppm Biodiesel from other sources may contain

higher levels of phosphorus ASTM D4951, Test Method for

Determination of Additive Elements in Lubricating Oils by

Inductively Coupled Plasma Atomic Emission Spectrometry,

shall be used for measuring phosphorus

Sodium and Potassium Combined Content

Sodium and potassium may be present in biodiesel as

abra-sive solids or soluble metallic soaps Abraabra-sive solids can

contribute to injector, fuel pump, piston and ring wear, and

also to engine deposits Soluble metallic soaps have little

effect on wear, but they may contribute to filter plugging

and engine deposits High levels of sodium or potassium

compounds may also be collected in exhaust particulate

removal devices, are not typically removed during passive or

active regeneration, and they can create increased back

pressure and reduced period to service maintenance Sodiumand potassium, combined can be determined using EN14538Fat and Oil Derivatives—Fatty Acid Methyl Ester (FAME)—Determination of Ca, K, Mg and Na Content by Optical Emis-sion Spectral Analysis with Inductively Coupled Plasma (ICPOES) Test Method UOP 391 Trace Metals in Petroleum Prod-ucts or Organics by AAA may also be used Test Method EN

14538 shall be the referee test method

Reduced Pressure DistillationBiodiesel exhibits a boiling point rather than a distillationcurve The fatty acid chains in the raw oils and fats fromwhich biodiesel is produced are mainly comprised of straightchain hydrocarbons with 16 to 18 carbons that have similarboiling temperatures The atmospheric boiling point of biodie-sel generally ranges from 330 to 357
C The reduced pressuredistillation limit of 360
C is not problematic and was added

to ensure the fuel has not been adulterated with high boilingcontaminants ASTM D1160, Test Method for Distillation ofPetroleum Products at Reduced Pressure, shall be used fordetermining reduced pressure distillation

Oxidation StabilityProducts of oxidation in biodiesel can take the form of vari-ous acids or polymers, which, if in high enough concentra-tion, can cause fuel system deposits and lead to filter cloggingand fuel system malfunctions Additives designed to retard theformation of acids and polymers can significantly improvethe oxidation stability performance of biodiesel There is noASTM test method to determine this property ASTM Specifi-cation D6751 specifies the use of EN14112, the RancimateTest, Fat and Oil Derivatives—Fatty Acid Methyl Esters(FAME)—Determination of Oxidation Stability (Accelerated oxi-dation test)

DENSITY AND RELATIVE DENSITYNone of the ASTM specifications set limits on the density ofoxygenates because the density is fixed by the other chemicaland physical properties of the materials Density relates to thevolumetric energy content of the fuel—the denser the fuel, thehigher the volumetric energy content although the oxygenpresent reduces the energy content Density is importantbecause oxygenates are often bought and sold with the volumecorrected to a specific temperature, usually 15.6
C (60
F) Vol-ume correction factors for oxygenates differ somewhat fromthose for hydrocarbons, and work is in progress to determineprecise correction factors for gasoline-oxygenate blends.Oxygenate density is determined by ASTM D4052/IP

365, Test Method for Density and Relative Density of Liquids

by Digital Density Meter

SAMPLING, CONTAINERS, AND SAMPLE HANDLING

Using the correct sampling procedures are critical for all fuelsand fuel components ASTM D4057, Practice for Manual Sam-pling of Petroleum and Petroleum Products, provides severalprocedures for manual sampling ASTM D4177, Practice forAutomatic Sampling of Petroleum and Petroleum Products pro-vides automatic sampling procedures For volatility determina-tions of a sample, ASTM D5842, Practice for Sampling andHandling of Fuels for Volatility Measurement, contains specialprecautions for sampling and handling techniques to maintainsample integrity ASTM D4306, Practice for Aviation Fuel

Sample Containers for Tests Affected by Trace Contamination,

should be used to select appropriate containers especially for

tests sensitive to trace contamination Also ASTM D5854,

Prac-tice for Mixing and Handling of Liquid Samples of Petroleum

and Petroleum Products, provides procedures for container

selection and sample mixing and handling For octane or cetane

number determination, protection from light is important

Collect and store sample fuels in an opaque container, such as adark brown glass bottle, metal can, or minimally reactive plasticcontainer to minimize exposure to UV emissions from sourcessuch as sunlight or fluorescent lamps For sampling of oxygen-ated materials water displacement must not be used, because ofpotential problems associated with the interaction of water withoxygenates

Applicable ASTM Specifications

D396 Specification for Fuel Oils

D975 Specification for Diesel Fuel Oils

D1152 Specification for Methanol (Methyl Alcohol)

D1193 Specification for Reagent Water

D4806 Specification for Denatured Fuel Ethanol for

Blending with Gasolines for Use as Automotive

Spark-Ignition Engine Fuel

D4814 Specification for Automotive Spark-Ignition Engine

Fuel

D5797 Specification for Fuel Methanol (M70-M85) for

Automotive Spark-Ignition Engines

D5798 Specification for Fuel Ethanol

(Ed75-Ed85) for Automotive Spark-Ignition Engines

D5983 Specification for Methyl Tertiary-Butyl Ether

(MTBE) for Downstream Blending with tive Spark-Ignition Fuel

Automo-D6751 Specification for Biodiesel Fuel Blend Stock (B100)

for Distillate Fuels D7467 Specification for Diesel Fuel Oil, Biodiesel Blend

(B6 to B20) D02:1347 Committee D02 Research Report on Reformulated

Spark-Ignition Engine Fuel

Applicable ASTM/IP Test Methods

Before using any test method, the Scope shall be reviewed to

make sure the test method is applicable to the product being

tested and that the specified measurement range covers the area

of interest.

D86 154 Test Method for Distillation of Petroleum

Products at Atmospheric Pressure D93 13 Test Methods for Flash Point by Pensky-

Martens Closed Cup Tester D130 131 Test Method for Detection of Copper

Corrosion from Petroleum Products by the Copper Strip Tarnish Test

D189 71 Test Method for Conradson Carbon Residue

of Petroleum Products D381 Test Method for Gum Content in Fuels by

Jet Evaporation D445 14 Test Method for Kinematic Viscosity of

Transparent and Opaque Liquids (and the Calculation of Dynamic Viscosity)

Residue of Petroleum Products D613 163 Test Method for Cetane Number of Diesel

Fuel Oil D664 Test Method for Acid Number of Petroleum

Products by Potentiometric Titration D874 139 Test Method for Sulfated Ash from Lubricat-

ing Oils and Additives

D891 Test Methods for Specific Gravity, Apparent,

of Liquid Industrial Chemicals D974 Test Method for Acid and Base Number by

Color-Indicator Titration D976 107 Test Methods for Calculated Cetane Index

of Distillate Fuels D1160 154 Test Method for Distillation of Petroleum

Products at Reduced Pressure D1266 13 Test Method for Sulfur in Petroleum Prod-

ucts (Lamp Method) D1613 131 Test Method for Acidity in Volatile Solvents

and Chemical Intermediates Used in Paint, Varnish, Lacquer, and Related Products D1688 Test Methods for Copper in Water D1796 Test Method for Water and Sediment in

Fuel Oils by the Centrifuge Method tory Procedure)

(Labora-D2622 Test Method for Sulfur in Petroleum

Prod-ucts by Wavelength Dispersive X-ray rescence Spectrometry

Fluo-D2709 Test Method for Water and Sediment in

Middle Distillate Fuels by Centrifuge D3117 Test Method for Wax Appearance Point of

Distillate Fuels D3120 Test Method for Trace Quantities of Sulfur

in Light Liquid Petroleum Hydrocarbons by Oxidative Microcoulometry