The fugitive emission test FET method involves pass- ing a controlled flow rate of a u through a test enclosure that is sealed to the top deck of a test pan over a test deck seam or over
APIReferences
Manual of Petroleum Measurement Standards:
5 “Guidelines for the Use of the Inter- national System of Units (SI) in the Petroleum and Allied Industries,” Second Edition, December 1980 9.2 “Evaporative Loss From Floating
Roof Tanks,” First Edition, April
9.3, Part F “Evaporative Loss Factor for Stor- age Tanks Certification Program,” First Edition, May 1997
9.3, Part G “Certified Loss Factor Testing Labo- ratory Registration,” First Edition, March 1997
9.3, Part H “Tank Seals and Fittings Certifica- tion Administration,” First Edition, March 1998
Standard 650 Welded Steel Tanks for Oil Storage, Tenth
ASTMReferences
D323 Test Method f o r Vapor Pressure of Petro- leum Products (Reid Method)
E220 Method for Calibration of Thermocouples by Comparison Techniques
IASTM International, 100 Bar Harbor Drive, West Conshohocken, Pennsylvania 19428
2 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 1 EVA EVAPORA TIVE LOSS MEASUREMENT
Definitions
A floating roof is created by placing a fixed roof over an external floating roof on top of the tank shell, transforming it into an internal floating roof while maintaining the external floating roof design These roofs are generally designed following the guidelines outlined in Appendix C of the API Standard 650.
Welded Steel Tanks for Oil Storage
The equipment used and process of receiving signals from sensors, determining the values corresponding to the signals, and recording the results
The floating roof of a bulk liquid storage tank provides essential buoyancy and structural support while covering most of the liquid surface It features an annular space around its perimeter, allowing it to move up and down as the tank is filled and emptied without binding against the tank shell This space is sealed by a flexible rim seal, and the deck may include penetrations secured by deck fittings to facilitate various operational functions.
The device effectively seals a penetration in the deck of a floating roof within a bulk liquid storage tank These penetrations are generally designed to support specific functional or operational features of the tank.
The construction of floating roofs involves the joints between adjacent deck sheets or panels Some internal floating roofs utilize deck sheets joined by mechanical means at the seams, which can lead to deck seam loss In contrast, other internal or external floating roofs are made of metal sheets that are welded together, eliminating the issue of deck seam loss.
The construction of a floating roof involves the critical intersections of deck seams, either with one another or with the rim of the roof Mechanically-joined deck seams feature deck joints at these intersection points, which are essential for structural integrity It is important to note that the deck joint locations incur a distinct deck joint loss, separate from the loss associated with the deck seams themselves.
The evaporative loss rate of a floating-roof storage tank is influenced by various factors, including climatic conditions and the properties of the stored liquid To determine the standing storage evaporative loss rate, the evaporative loss factor for each contributing device is adjusted based on these characteristics Key properties of the stored liquid include its vapor pressure function, vapor molecular weight, and product factor.
A floating roof is situated in a bulk liquid storage tank without a fixed roof, exposing it to environmental conditions In contrast, internal floating roofs are found in tanks with a fixed roof that shields them from such exposure External floating roofs are generally designed following Appendix C of the API Standard 650, which pertains to welded steel tanks for oil storage.
The Fugitive Emission Test (FET) facility encompasses all necessary components for conducting emissions testing, including the test pan, test enclosure, pressure and temperature sensors, data acquisition system, sample and dilution air pumps, total hydrocarbon analyzers, flow meters, and associated flow tubing.
A floating roof device is designed to rest on the surface of liquids in bulk storage tanks, effectively minimizing evaporation by covering the liquid product This system includes a deck, rim seal, and various deck fittings, ensuring optimal performance in reducing exposure to the atmosphere.
The article discusses a test method for determining evaporative deck-seam and deck-joint loss factors in mechanically-joined deck seams of internal floating-roof tanks This method, known as the fugitive emission test (FET), involves directing a controlled flow of air through a sealed test enclosure positioned over a test deck seam or joint, which is placed above a test pan filled with a volatile hydrocarbon liquid The test measures the total hydrocarbon concentration in the air entering and exiting the enclosure.
PART FUGITIVE EMISSION TEST METHOD FOR THE MEASUREMENT OF DECK-SEAM LOSS FACTORS FOR INTERNAL FLOATING-ROOF TANKS 3
' measured, along with the flow rate of the air leaving the test enclosure, at specified pressure differences across the test deck seam or test deck joint
An indicator is a device that displays or records signals from a sensor, converting them into useful measurement units For instance, an electronic signal received in volts may be shown as pounds Often integrated into electronic data acquisition systems, these indicators can be pre-programmed to record data at specific intervals, analyze the received data, and electronically store the results.
A device used in the measurement process to sense, trans- mit, or record observations
Internal floating roofs are designed to operate within bulk liquid storage tanks that feature a fixed roof, providing protection from environmental conditions Unlike external floating roofs, these internal structures are safeguarded from exposure, ensuring their integrity and functionality The design of internal floating roofs adheres to the guidelines outlined in Appendix H of the API.
Standard 650, Welded Steel Tanks for Oil Storage
The evaporative loss characteristics of a liquid product are determined by a specific factor To calculate the standing storage evaporative loss rate of a bulk liquid storage tank with a floating roof, the product factor, vapor pressure function, and vapor molecular weight are multiplied by the total of the equipment loss factors.
A flexible device that spans the annular rim space between the tank shell and the perimeter of the floating roof deck
Effective rim seals are essential for closing the annular rim space, accommodating irregularities between the floating roof and the tank shell, and centering the floating roof while allowing for its normal movement.
An instrument is used to detect specific attributes or measurement data during a measurement process This data is subsequently transmitted to an indicator for display or recording purposes.
Units of Measurement
This standard utilizes inch-pound units from the English system, referencing values from the U.S National Institute of Standards and Technology (NIST) While the standard does not provide equivalent International System of Units (SI) values, guidance for converting to SI and other metric units is available in Appendix B, Metric Units, and the API Manual of Petroleum Measurement Standards Chapter 15.
The primary units of measurement include length, mass, force, time, and temperature Length is measured in miles (mi), feet (ft), or inches (in) Mass is quantified in pounds (lb), while force is expressed in pound-force (lbf) Time can be represented in hours (hr) or years (yr) For temperature, the degree Fahrenheit (°F) and degree Rankine (°R) are the standard units used.
4 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 19.3-EVAPORATIVE LOSS MEASUREMENT
The unit of pressure is the pound-force per square inch absolute, designated psia
The unit of reporting deck-seam loss factors is the pound- mole per foot of deck seam per year, designated lb-mole/ft yr
The deck-seam loss factor, Kd, does not directly represent the pound-moles of vapor loss over time; instead, it serves as a multiplier for certain dimensionless coefficients to calculate the actual evaporative loss in pound-moles for a specific liquid product To convert the units of the deck-seam loss factor from pound-moles per foot per year to a loss rate in actual pound-moles per foot per year, Kd must be multiplied by the dimensionless vapor pressure function.
P * , which is a function of the product vapor pressure and atmospheric pressure, and by the dimensionless product factor, K,
A pound-mole (lb-mole) refers to a quantity of a substance whose mass in pounds matches the numerical value of its molecular weight.
To convert the pound-moles of a liquid product lost per foot of deck seam annually into pounds per year, the loss rate (Kd P* K,) is multiplied by the total length of the deck seam (Ld) in feet and the molecular weight (M) of the liquid product in its vapor phase, measured in pounds per pound-mole For more detailed information on this calculation, refer to the API Manual of Petroleum.
The unit of reporting deck-joint loss factors is the pound- mole per year per deck joint, designated lb-mole/yr
The deck-joint loss factor, K, is not measured in pound-moles of vapor loss over time; instead, it represents a unit of a factor that needs to be multiplied by specific coefficients.
To calculate the actual pound-moles of evaporative loss over time for a specific liquid product, the dimensionless deck-joint loss factor, \( K_j \), must be converted from pound-moles per deck joint per year to a loss rate in actual pound-moles per deck joint per year This conversion involves multiplying \( K_j \) by the dimensionless vapor pressure function, \( P^* \), which depends on the product's vapor pressure and atmospheric pressure, as well as the dimensionless product factor, \( K \).
To then convert the actual pound-moles per year per deck joint to pounds per year of a given liquid product, the loss rate
The formula involves multiplying the dimensionless total number of floating roof deck joints, \(N_j\), by the molecular weight of the liquid product in its vapor phase, \(M\), which is expressed in pounds per pound-mole For more detailed information, refer to the API Manual of Petroleum Measurement Standards, Chapter 19.2.
Nomenclature
Constant in the vapor pressure equation, dimen- sionless
Constant in the vapor pressure equation, OR
Concentration of hydrocarbon vapor in the test enclosure inlet air, ppmv
Concentration of hydrocarbon vapor in the test enclosure outlet air, ppmv
Density of hydrocarbon vapor in the test enclosure outlet air at standard conditions, lb/sft3
Test enclosure loss rate, lb/min
Test enclosure loss factor, lb-mole/yr
Product factor of the test liquid, dimensionless Deck-seam loss factor, Ib-mole/ft yr
Deck-joint loss factor, lb-mole/yr
Length of test deck seam, ft
Molecular weight of the test liquid vapor, lb/lb- mole
Total number of deck joints on the floating roof deck, dimensionless
Vapor pressure of the test liquid, psia
Pressure difference between the pressure inside the test pan vapor space and the inside the test enclosure, in wc
Volumetric flow rate of the test enclosure outlet air at standard conditions, sft3/min
PART &FUGITIVE EMISSION TEST METHOD FOR THE MEASUREMENT OF DECK-SEAM LOSS FACTORS FOR INTERNAL FLOATING-ROOF TANKS 5
R Universal gas constant (10.73 l), ft3 psia/lb-mole
Reid vapor pressure of the test liquid, psi
Slope of the test liquid ASTM-D86 distillation curve at 10 volume percent evaporated, O F / volume %
Tl Temperature of the test liquid, OF or OR
T, Standard temperature (60°F or 519.67”R), OF or
The standard test method employs a mass balance procedure to quantify evaporative loss through a test deck seam or joint A test pan, equipped with a test deck seam, is covered by a sealed test enclosure It is filled with a volatile hydrocarbon test liquid, such as normal-hexane or iso-hexane, to a specified height Air is then passed through the enclosure at a controlled flow rate, maintaining a pressure difference between the vapor space in the test pan and the enclosure Continuous measurements of total hydrocarbon concentration in the incoming and outgoing air are taken using analyzers By performing a mass balance on the hydrocarbon vapor, the evaporative loss rate through the seam or joint is calculated This loss rate is adjusted based on the properties of the test liquid and the length of the seam to derive an evaporative deck-seam or deck-joint loss factor.
This test method outlines a procedure for determining the evaporative deck-seam loss factor or deck-joint loss factor of mechanically joined deck seams in internal floating-roof tanks Testing must be conducted in an API-approved laboratory, following the guidelines set forth in the API Manual of Petroleum Measurement.
The values obtained from the Certified Loss Factor Testing Laboratory Registration, as outlined in Standards, Chapter 19.3, Part G, must be assessed following the guidelines set forth in the API Manual of Petroleum Measurement Standards, Chapter 19.3, Part.
F, “Evaporative Loss Factor for Storage Tanks Certification
The program enables manufacturers of floating-roof deck seams or joints to obtain API-certified loss factors for their proprietary designs This process involves a laboratory approval procedure, a specific test method, and an evaluation method, ensuring that the tested deck seams or joints meet the necessary standards.
Evaluation of Results
The results of this test method are not intended to be used apart from their evaluation in accordance with the API Man- ual of Petroleum Measurement Standards, Chapter 19.3, Part
F, “Evaporative Loss Factor for Storage Tanks Certification Program.”
Low Loss Rates
This test method is not valid for deck seams or deck joints that have a loss rate lower than the specified tolerance of the instruments
If the loss rate of the test deck seam or joint is below the instrumentation's detection limit, the test results report must include the minimum value for the deck-seam or deck-joint loss factor, as determined by the detection limit of the instrumentation.
Test Apparatus Illustrations
Figures 1, 2, and 3 depict the test apparatus designed to measure the certified evaporative deck-seam loss factor for mechanically-joined deck seams used on internal floating roofs Figure 1 presents a flow diagram showcasing the test equipment and instrumentation, while Figure 2 offers a plan view of the fugitive emission test facility, detailing the arrangement of the test equipment within the test room Lastly, Figure 3 illustrates the test assembly, highlighting the positioning of the test enclosure over the test deck seam on the test pan.
TestRoom
The test room must be spacious enough to accommodate the necessary testing equipment, instrumentation, and personnel It should be designed to maintain the air temperature within ±5°F of the chosen test temperature throughout the entire testing period.
The test room should be insulated to aid in the control of the air temperature within the test room
6 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 1 EVAPORATIVE TIVE LOSS MEASUREMENT
The test room shall have a dedicated temperature control system for maintaining the air temperature within the test room The test room may also have a dedicated heater and air conditioner
The test room shall be equipped with a fan that circulates the air within the test room to reduce air temperature varia- tions in the test room
The air that is directed into the test enclosure may be drawn from the air inside of the test room
The test room must have a sufficiently large equipment access door to facilitate the installation and removal of test assemblies Additionally, a smaller personnel access door should be included to allow access to the instrumentation and data acquisition system, as well as to enable inspection of the test assembly throughout the testing process.
Test Assembly
Figure 3 illustrates a test assembly, which consists of a test pan, test deck seam or test deck joint, test enclosure, and test
The rectangular test pan features a top deck that mimics an internal floating roof It includes both a fill and a drain connection for efficient liquid management Additionally, the test pan is designed to accommodate a test deck seam with a minimum length of 10 feet.
The test pan may incorporate multiple test deck seams
When installing multiple test deck seams on the top deck of the test pan, it is essential to maintain a minimum spacing of at least 1 foot between the centers of adjacent seams Additionally, there should be a minimum distance of 1 foot from the longitudinal edge of the test pan to the nearest test deck seam.
The test pan must include a vent connection to maintain the vapor space above the test liquid at near atmospheric pressure This vent connection can be linked to a vent pipe that leads outside the test room.
The test pan shall be equipped with a thermocouple that permits measuring the temperature of the test liquid during the test period
The test pan can be placed on any appropriate surface, but it must be positioned to ensure that the test liquid level is consistent across the test pan in relation to the test deck seams or joints When evaluating deck seams or joints that typically come into contact with the liquid in a floating roof tank, it is crucial to adjust both the test liquid level and the test pan position so that every part of the test deck seam or joint interacts with the test liquid as it would during regular operation.
To accurately assess the deck-seam loss factor for a specific deck seam type, the seam must be installed on the top deck of the test pan following the manufacturer's standard assembly procedures However, for the end joints where the test deck seam meets the ends of the test pan, alternative construction methods may be employed if these joints are outside the test enclosure, allowing for easier installation of the test deck seam.
The surfaces of the test deck seam shall be clean and free of oil or other materials that may affect the deck-seam loss factor test results
To accurately assess the deck-joint loss factor for a specific deck joint type, it is essential to install the joint on the test pan's top surface following the manufacturer's assembly and installation guidelines The tested deck joints must be integrated into the deck seam section located within the test enclosure.
A test deck seam can consist of several test deck joints, and when this is the case, it is essential to maintain a minimum spacing of at least 1 foot between the centers of adjacent joints.
The surfaces of the test deck joint shall be clean and free of oil or other materials that may affect the deck-joint loss factor test results
A test enclosure shall be placed over the test deck seam and test deck joint, if a test deck joint is incorporated into the test deck seam
The test enclosure must be securely sealed to the top surface of the test pan deck and to the seams of the test deck that extend into the ends or side walls of the enclosure To achieve this necessary seal, a caulk, such as silicone caulk, can be utilized.
A leak-tightness test is conducted on the test enclosure to verify that there are no leak paths around its perimeter, particularly where it is sealed to the top.
PART û-FUGITIVE EMISSION TEST METHOD FOR THE MEASUREMENT OF DECK-SEAM LOSS FACTORS FOR INTERNAL FLOATING-ROOF TANKS 7
A leak-tightness test involves applying a slight gas pressure inside the test enclosure while using a leak detection liquid, typically a soap-like solution, on the sealed edges The formation of bubbles indicates vapor leaks; if no bubbles are detected, it can be concluded that the test enclosure is free of significant leaks.
The test enclosure must feature an inlet connection at one end to allow air intake and an outlet connection at the opposite end to expel air that has absorbed hydrocarbon vapor due to evaporative losses from the test deck seam or joint.
To accurately measure the deck-seam or deck-joint loss factor, it is essential to maintain the pressure within the test enclosure at specified vacuum levels in relation to the vapor space pressure of the test pan.
The test liquid must be kept at a level that aligns with industry standards for the specific deck seam or joint being evaluated.
The test liquid used must be normal-hexane (n-hexane) or iso-hexane of technical grade or higher It is essential that the temperature of the test liquid does not exceed its normal boiling point during testing Additionally, a sample of the test liquid should be analyzed to determine its Reid vapor pressure following ASTM D323 standards.
To minimize the required quantity of test liquid, it can be floated on top of water, ensuring that the layer of test liquid completely covers the water's surface throughout the test This layer must be deep enough to prevent the vapor pressure of the test liquid from decreasing by more than 5 percent due to the evaporation of lighter hydrocarbon components Additionally, at least one thermocouple must be positioned within 1 inch below the surface of the test liquid.
Test Apparatus Air Flow
Figure 1 presents a flow diagram of the test apparatus, showcasing the instrumentation and flow lines utilized for controlling and sampling the airflow within the test enclosure Detailed descriptions of the instrumentation can be found in Section 10.
Air samples entering and leaving the test enclosure must be continuously monitored to determine the total hydrocarbon concentration As shown in Figure 1, inlet and outlet sample pumps are utilized to extract air samples from both streams and direct them to total hydrocarbon analyzers These sample pumps should be diaphragm-type compressors to ensure that the air is compressed without any oil contamination.
The test procedure mandates that the pressure difference across the test deck seam or joint be maintained between 0.0 and 0.1 inches of water column This necessitates that the pressure within the test enclosure remains a vacuum compared to the vapor space pressure of the test pan.
The outlet sample pump serves a dual purpose: it establishes the necessary vacuum within the test enclosure to maintain a specific pressure difference across the test deck seam or joint, while also sampling the air that exits the enclosure To effectively manage and measure the airflow rate, an outlet flow control valve and an outlet flow meter are utilized alongside the pump In situations where a greater airflow rate is needed to create the required pressure difference, the outlet sample pump may extract more air than what is necessary for sampling, with the excess air being vented outside the test room.
In some tests, the concentration of total hydrocarbons in the air exiting the test enclosure can surpass the maximum range of the outlet total hydrocarbon analyzer To address this, a sample dilution system can be employed to mix the outlet air sample with a precise amount of dilution air, effectively reducing the total hydrocarbon concentration for accurate measurement.
TestLiquid
The test liquid must be kept at a level that aligns with industry standards for the specific deck seam or joint being evaluated.
The test liquid used must be normal-hexane (n-hexane) or iso-hexane of technical grade or higher It is essential that the temperature of the test liquid does not exceed its normal boiling point during testing Additionally, a sample of the test liquid should be analyzed to determine its Reid vapor pressure following ASTM D323 standards.
To minimize the required quantity of test liquid, it can be floated on water, ensuring that the layer of test liquid completely covers the water's surface throughout the test The depth of this layer must be adequate to prevent the vapor pressure of the test liquid from decreasing by more than 5 percent due to the evaporation of lighter hydrocarbon components Additionally, at least one thermocouple must be positioned within 1 inch below the surface of the test liquid.
Test deck seams and joints in floating-roof storage tanks that come into contact with liquid products must be evaluated under identical conditions The height of the test liquid should be set to ensure it interacts with the test deck seam or joint in the same way as it does during regular operation.
To effectively monitor the liquid level in the test pan, a reliable indication method is essential for both initial filling and ongoing observation during testing The ideal solution is a sight tube or window, although alternative methods that prevent the loss of test liquid or its vapors are also acceptable.
All liquid-level fittings on the test pan, as weil as those used for filling and emptying the test pan, must be leak tight
Figure 1 presents a flow diagram of the test apparatus, showcasing the instrumentation and flow lines utilized for controlling and sampling air flow within the test enclosure Detailed descriptions of the instrumentation can be found in Section 10.
Air samples entering and leaving the test enclosure must be continuously monitored to determine the total hydrocarbon concentration As shown in Figure 1, inlet and outlet sample pumps are utilized to extract air samples from both streams and direct them to total hydrocarbon analyzers These sample pumps are diaphragm-type compressors designed to compress the air without introducing oil contamination.
The test procedure mandates that the pressure difference across the test deck seam or joint is maintained between 0.0 and 0.1 inches of water column This necessitates that the pressure within the test enclosure is kept at a vacuum compared to the vapor space pressure of the test pan.
The outlet sample pump serves a dual purpose: it establishes the necessary vacuum within the test enclosure to maintain a specific pressure difference across the test deck seam or joint, while also sampling the air that exits the enclosure To effectively manage and measure the airflow rate, an outlet flow control valve and an outlet flow meter are utilized alongside the pump In situations where a greater airflow rate is needed to create the required pressure difference, the outlet sample pump may extract more air than what is necessary for sampling, with the excess being vented outside the test room.
In some tests, the concentration of total hydrocarbons in the air exiting the test enclosure can surpass the maximum range of the outlet total hydrocarbon analyzer To address this, a sample dilution system can be employed to mix the outlet air sample with a precise amount of dilution air, effectively reducing the total hydrocarbon concentration for accurate measurement.
8 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 19.3-EVAPORATIVE LOSS MEASUREMENT
The PART & Fugitive Emission Test Method is designed to measure deck-seam loss factors for internal floating-roof tanks, focusing on the concentration of hydrocarbons in the diluted outlet air sample across the full-scale range of the total hydrocarbon analyzer.
Figure 1 depicts a dilution system featuring two banks of rotameters: one for measuring the flow rate of the outlet air sample from the test enclosure and another for the dilution air By pairing different outlet air and dilution air rotameters, the total hydrocarbon concentration in the diluted outlet air sample can be adjusted to fit the full-scale range of the total hydrocarbon analyzer The dilution air is supplied by a pump that draws air from the test room.
This test method evaluates mechanically-joined deck seams or joints in internal floating-roof tanks using full-scale samples The samples must be constructed following the manufacturer's standard practices and should incorporate all features typical of actual usage.
The deck seams or joints designated for testing must be securely fastened to the top deck of the test pan, mirroring the attachment method used for internal floating roofs in real-world applications.
Test deck seams and test deck joints that normally contact the liquid product on a floating roof in service shall be mounted in a similar manner on the test pan
The seams or joints of the test deck that meet the end or side walls of the test enclosure must be properly sealed to ensure integrity This can be achieved using an appropriate sealant or caulk.
Test Item Placement
To install the test deck seam or joint on the test pan, follow the guidelines outlined in sections 7.3.2, 7.3.3, and 8.2 Next, place the test enclosure over the seam or joint and ensure it is sealed to the top deck of the test pan, as detailed in sections 7.3.4 and 8.3.
Fill the test pan with the test liquid to the proper liquid level, as described in 7.4.
Instrumentation Attachment
Attach the instrumentation tubing to the test enclosure and test pan, as described in 7.5.
Test Room Air Temperature Control
Start the test room air temperature control system to adjust the test room temperature to the selected value
Start the inlet sample pump, outlet sample pump, and dilution air pump to establish the required pressure difference between the vapor space in the test pan and the pressure in the test enclosure, as outlined in section 11.1.
Steady-State Operation
Begin the data acquisition system to monitor temperatures, pressures, and total hydrocarbon concentrations until a stable evaporative loss rate is reached If the total hydrocarbon concentration in the outlet air sample surpasses the analyzer's full-scale range, modify the sample dilution accordingly, as outlined in section 7.5.3.
After the initial startup phase, where the evaporation rate stabilizes, the recorded test data from the data acquisition system will be used to calculate the deck-seam or deck-joint loss factor The steady-state test period must last at least one hour, as outlined in Section 11.3.
To accurately measure each parameter, it is essential to utilize a sensor, an indicator, and a data recording method The following specifications outline the necessary instruments, measurement techniques, and accuracy standards Calibration procedures are detailed to reduce systematic errors or biases in the instruments A summary of the instrument requirements can be found in Table 1.
Procedures are established to minimize random errors in the measurement process, particularly in steps like indicating and recording observed values This process, known as data acquisition, involves receiving signals from sensors, determining their corresponding values, and documenting the results To ensure accuracy and control, data acquisition will be performed using a programmable electronic system that adheres to specified tolerances for frequency and precision of observations.
10 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 1 EVAPORATIVE TIVE LOSS MEASUREMENT
Instrument Type Tolerable Error Calibration Interval Time of the observation
Temperature of the test liquid
Temperature of the air in the test room
Temperature of the air at flow rate sensors
Pressure of the air entering the test enclosure
Pressure of the air leaving the test enclosure
Pressure of the air leaving at the flow rate sensors
Atmospheric pressure in the test room
Pressure difference across the test deck seam
Flow rate of air leaving the test enclosure
Flow rate of the undiluted outlet air sample
Flow rate of the dilution air
Total hydrocarbon concentration in the test enclosure inlet air
Total hydrocarbon concentration in the test enclosure outlet air
Clock of the DAS Thermocouple Thermocouple Thermocouple Pressure sensor Pressure sensor Pressure sensor Pressure sensor Pressure difference sensor Flow rate sensor
Flow rate sensor Flow rate sensor Total hydrocarbon analyzer Total hydrocarbon analyzer f O l % f0.5"F f0.S0F f0.5"F f l % f l %
6 months Every test Every test
The accuracy of the sensors will be validated through the readings from the data acquisition system, ensuring both the indicator and the sensor are verified Calibration standards must be traceable to the national measurement reference standards upheld by NIST.
The temperature measurement system will utilize thermocouples to detect temperature changes of ±0.2°F, ensuring high accuracy in data transmission to the data acquisition system.
Data Acquisition System
The data acquisition system must effectively record all data from sensors and include a chronometer with a maximum interval of one second and an accuracy of 0.1 percent It should be programmable to capture individual sensor readings at designated frequencies and provide real-time display of observed values to promptly identify and rectify any out-of-specification conditions.
Thermocouples must be strategically positioned to accurately measure the bulk temperature of the test liquid, the air temperature in the test room, and the temperature of the air flowing through the outlet air flow meter of the test enclosure.
When utilizing a dilution system to dilute the air sample from the test enclosure outlet, it is essential to position a thermocouple to measure the temperature of the air exiting the dilution system's flow meters Calibration of the sensors should be verified using the data acquisition system as the indicator.
PART &FUGITIVE EMISSION TEST METHOD FOR THE MEASUREMENT OF DECK-SEAM LOSS FACTORS FOR INTERNAL FLOATING-ROOF TANKS 11
A thermocouple must be positioned within 1 inch below the surface of the test liquid in the test pan to accurately measure the bulk temperature, provided that the temperatures of the water and the test liquid are the same, as illustrated in Figure 3.
A thermocouple shall be located near the test assembly to measure the air temperature in the test room, as shown in
10.3.1 -3 Test Enclosure Outlet Air Temperature
A thermocouple should be positioned in the outlet air line of the test enclosure to accurately measure the temperature of the air flowing through the outlet air flow meter, as illustrated in Figure 1.
10.3.1 -4 Dilution System Outlet Air Temperature
A thermocouple shall be located in the dilution system out- let air line to measure the temperature of the air leaving the dilution system flow meters, as shown in Figure 1
Each thermocouple shall be calibrated in accordance with
ASTM E220 outlines the use of a temperature measurement system, where all thermocouple calibrations must adhere to the temperature-electromotive force tables specified in ASTM E230 It is essential that the observed values do not deviate from the true values by more than 10.5°F.
High-precision pressure sensors must be utilized to obtain gage pressure readings in relation to the atmospheric pressure of the test room When employing high-precision electronic pressure sensors, their output signals should be directly captured by the data acquisition system.
The pressure being measured shall not exceed the sensor's measurable range, even during brief periods of pressure fluctuations
Pressure taps must be strategically positioned to measure the air pressure entering and exiting the test enclosure, as well as the pressure at the outlet air flow meter, as illustrated in Figure 1.
When utilizing a dilution system to dilute the air sample from the test enclosure outlet, it is essential to install a pressure tap to measure the pressure of the air exiting the dilution system flow meters, as illustrated in Figure 1.
The pressure sensors shall be calibrated The accuracy of electronic pressure sensors shall be based on the readings indicated by the data acquisition system
The zero setting of the pressure sensors shall be checked and adjusted, if necessary, before each test
The atmospheric pressure will be measured using an electronic pressure sensor, which will transmit the signal to the data acquisition system This sensor is designed to detect changes in atmospheric pressure of 0.01 psia, with a proven accuracy of 0.05 psia.
The atmospheric pressure sensor shall be located near the data acquisition system to measure the atmospheric pressure in the test room, as shown in Figure 1
The atmospheric pressure sensor must be calibrated at a minimum of two pressure levels using the atmospheric pressure measurement system The observed values should not deviate from the true values by more than 10.05 psia The accuracy of the atmospheric pressure sensor will be determined based on the readings provided by the data acquisition system.
A high-precision electronic pressure difference sensor will measure the pressure difference across the test deck seam or joint, with the output signal recorded directly by the data acquisition system It is essential that the measured pressure remains within the sensor's measurable range, even during short periods of pressure fluctuations.
The pressure difference sensor must be connected to two pressure taps: the high pressure side to the vapor space of the test pan and the low pressure side to the test enclosure, as illustrated in Figure 1.
The pressure difference sensor must undergo calibration to ensure accuracy, which is determined by the readings from the data acquisition system Additionally, the zero setting of the sensor should be verified and adjusted as needed prior to each test.
12 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 19.3-EVAPORATIVE LOSS MEASURE MEN^
PART D-FUGITIVE EMISSION TEST METHOD FOR THE MEASUREMENT OF DECK-SEAM LOSS FACTORS FOR INTERNAL FLOATING-ROOF TANKS 13
14 API MANUAL OF PETROLEUM MEASUREMENT STANDARDS, CHAPTER 19.3-EVAPORATIVE LOSS MEASUREMENT
High-precision gas flow meters, including gas rotameters, are essential for accurately sensing flow rates When utilizing high-precision electronic flow rate sensors, their output signals must be directly recorded by the data acquisition system It is crucial that the measured gas flow rates remain above 10 percent of the meter's or sensor's full-scale range.
A flow meter shall be located to measure the flow rate of the air leaving the test enclosure, as shown in Figure 1