flame safeguard control phần 8 pot

Longer wires, spliCed to these 2 wires, are connected 10 a remote PUSh-bulton switCh, Pressing the push-bu!lon switch ener­gizes the solenoid and activates the plunger, The plunger awlie

Honeywell sail switches (Fig T7) are used in flame A small metal sail, mounted on a pivOI, 9Klends inlolhe safeguard applications to prove combustion airflow before air stream Mechanical linkage transmits mol ion of the sail 1I1OJhloft ar.d while the burner is running They can also be to a switch The switch makes or breaks when the airflow used in air ducls to assure that a furnace is supplying reaches a speCified velocity The switch can be used in

Honeywell sail switches available for use in name safe­guard systems are listed in Table VI al the end of the sec­tion Table VI includes switching action, operating air velocity and direction, sail size and malerial, and special applications For further Information, refer fa the Instruc­

tion sheets tor the sail switches

54J7A,e; SU1A

FIG 77-HONEYWU~ SAIL SWITCHES

TABLE VI-SUMMARY OF HONEYWELL SAIL SWITCHES

S837A switch; one set

breaks

b Adjustable to aetlJale on upwarr:i airlDw (t:lr

" same a9 5437A axcept wiIhout case and

d AJso oparates lor upward air1k:lW, but operating air

, ~.'

S43 SAIL SWITCHES S43 Sail Switches are especially suited for use with gas-firacl unit heaters and air conditioning systems All models have a steel sail which actuates an sps.I mercury

600,1000, or 12501eel per minute [3.05, 5.1, or 6.4 metres per second] Several sail sizes are available 10 accommo­

date various sizes of air duels Models are available for usa in horizontal or va/lical duelS, and to actuate for any direction of airflow except downward

The.switCh iN !HE S43A or B modelS makes on increas·

lnQ air velocity; the switch in the S43D breales S43A med­

els 3r~' dasigrted 10 operate in airflow !rom lett 10 right (lOOking allha face oflhe switch so the label can be read)

S43B and D models operate in airtlow from rl""llo left

One S43B model is adjustable 10 operate in upwaIdair110w

"E"cu,,~

lwPTCN

L :~~_r -CONOU" CONNECT'ON

SCREw TER"'NAL5 (2)

FIG 78- S43 SAIL SWITCH WITH COVER

REMOVEO

5437, S637 SAIL SWITCHES

5437 and 5637 sail Swilches are especially suited for use in larm crop dryers AU models have an aluminum sail whiCh actuates a MICRO SWITCH snap-acting switch

5437 models have an $pSI switch; 5637 models have ",n spdt switch Models with standard size sails (1 x 3 inches [25.4 x 76.2 mmjj actuate at an air velocity at '900 faet per

minute (9.6 metres per second) with the differential set at its minimum value They acluate at 2250 fee! per minute [11.4 metres per second] with the differential at its maxi­mum value Other sail sizes result in different operating air velocllies (see Table VI) All models are designed to cper· ate In a horizontal airflow; lhey wIll also cperale in an u,r ward airflow, but the cperaling air velocity will change The 5437B is the same as the 5437A except that it does not have a case and caver In both models, lhe swilch makes on increasing air velocity (Fig 79) In the 5637A, one set of contacts makes (R to B) and the other set breaks (R 10 IN) on increasing air velocity (Fig 80) The normally cpen contact enerQizes the load when the air ve­loCity is great enough, and the normally closecl contact en­ergizes an alarm when the air velocity drops off

tror vertical ducts)

The S43 Sail Switch may be used on several different types Of applicaticns; therefore, the location and Installa­

tion will depend on the speCifiC jc:tl The case is usually mounled on the side ot a ducl or unil healer in a vertical

(upright) posilion The top of the case must be level lor pTq:lElr cperalion of the mercury swilch The sail should be

in the direct path of the airstream where the movement 01 the air will be unrestricted, and must be free to return to the -down" position under its own weight Wiring is routed lhrough the conduil oullel in the bottom of the case, and tnen connected to the 2 screw terminals on the terminal block inside the case (FiQ 78)

SoUJA OR B

"

& M""l<E5 01'1 'I'ICIlE""5'I'IG AlII VELOCITY

• A LOAO

FIG 79-S437A OR B INTERNAL SCHEMATIC

FIG 80-S637A INTERNAL SCHEMATIC

The 5437 or 5637 should be located so that the sail is in the direct path Of an unrestricted airstream It cperates basI in a horizontal duct In a vertical duct, the effect of gravity on the linkage changes lhe operatil"lQ painl Wiring

is rouled thrDLlQh the knockouts in each end of the case, ilJ"Id then connected to the screw terminals on the switch inside the case (Fig 81)

The differential on an S437A,B or 5637A sail Switch can be adjusted by lurning the differen.tial setting dial (Fig 81) The dial is marked with the lellers A, B, C, and 0 to indicate relative differentials from a minimum of 550 fpm (feet per minute) [2.8 metres per second, or m/s] to a maxi­

25

~:'<oc~ours (i)

DifFERENTIAl SETTING DIAl

""

FIG 81- S637A SAIL SWITCH WITH COVER

REMOVED (S437A OR B IS SIMILAR

EXCEPT FOR TERMINALS.)

mum of 900 tpm [4.6 m/s) For sail switches with the stan·

dard 1 x 3 inch [25.4 x 76.2 mm] sail, a minimum setting

(p:)sition A) resulls in an cperating air velocily of 1900 tpm

[9.6 m/sl (Fig 62) A maximum selting (positioo OJ results

in an cperaling air velocity ot 2250 tpm [ 71.4 rn/sJ The

switch breaks at 1350 tpm [6.9 rTVsl on decreasing air

velocity

The cperating air velocity and the differential are in­

versely proportional lo the area of the sail Urger sails re­

sult in operalion at lower air velocities and lhe dinerential

SPARK IGNITER

Q624A SOLID STATE SPARK GENERATOR

The Honeywell Q624A Solid State Spark Generator

(Fig 83) is used to ignite gas pilots with spark gaps up to

1/4 inch [6.6 millimelr8$] on commercial or irdustrial gas

burners It prevents detection of the ignition sPark when

prcperly applied in a flame deteclion system using a

C7027 C7035, or C7044 Minipeeper Ultraviolet Flame

Detector

The Q624A is rated for a 120 volt, 60 Hz power supply,

and prOVides 60 Sparks par'!ieCQr1(j with a peak voltage of

15,000 volls It is recommended for use with Ihe RA890G,

R4795, R4126, R4127, R4140, and R4150 Flame Safe­

guard Controls II is a solid state device and weighs only 3

pounds [1.4 kilograms] versus 8-1/2 p:xJnds l3.9 kilo­

grams} for standard Ignition transtonners

The sPark generator and the Mlnipeeper ullraviolet

flame deleclor are synChronized by the 60 Hz ac supply

voltage (Fig 84) They operate only during a small portion

at the cycle (shown by shaded areas) The spark occurs

during one-half of the cycle and the detector cperatBS dur­

ing the opposite hait cycle Thus, the tlan-e detector is

never "IOOdng· when there is a spark

INSTALLING THE 0624A

MOUNTlNG

The Q624A mounts in Ihe same space used by a con·

ventional ignilion transformer The mounting plate permits

"•• "M+

~' VM C'''~~~''''''l,

Klimo 0 Itoo "M)M,"'''V''

FIG 82-ADJUSTABLE DIFFERENTIAL FOR AN

S437A,B OR S637A SAIL SWITCH (WITH STANDARD 1 X 3 INC'" (25.4 X 76.2 mm] SAIL SIZE)

decreases prc:portionately To Increase the cperaling air

velocity, the sail can be trimmed uSing a hea"Y shears If it

is cut to one·half its original size, the cperaling air velocity

and the differential will be dovtied

Follow the instructions of lhe system manufacturer, if available, or adjust the differential ar"d/or sail size 10 suit the requirernef1ts of your awlication

HIGH VOlTAGE El,.EC:TROOE

lhe use at the same mounllng holes without an adapter

plale, and it may be mounled in any posillon

062.'" SP"'A~

GENERATOR

Ef:lERGIZEO

IFLA"E OlTiCTOIl OHI

FIG 84- SYNCHRONIZATION OF A Q624A

SOLIO STATE SPARK GENERATOR

FLAME DETECTOR

WIRING

The voltage and frequency of the power s~ly cen

netted to the Q624A must be 120 volts, 60 Hz The chaSSis

of the Q624A must be propfufy grounded at 9JI times, even

dUrlngbench testing; otherwise, the device may bum out

Loosen the cover screw (Fig 83) and remove the cover

Insert the 2leact.viras (NEC Class 1) through the knockout

in the boltom at the cese and connect them fa the screw

terminals on the terminal board, and to the terminal strip or

wirIng sl.Jbbase 01 the flame safeguard control (refer to Ta­

bla VII and Fig 85 or 86) Terminals T1 and T2 on the

Q624A must be connected to the prc:per terminals of the

flame sa1ElQuard control, as given in Table Vll If the name

deteclof and the ignition transformer are nor properly Con­

nected, the detector may sense ignition spark, which could

cause a hazardous condition

TABLE VII-WIRING CONNECTIONS FOR THE

0624A SOUD STATE SPARK GENERATOR

TER_ FLAME SAFEGUARD

Apprtlprlate ignition terminal

R4126 and R4127 T, lIS specified on ptDgrarrmel'

Instruction sheeL

l2 R4140 and R4150

T1 Appropriate Igntllon terminal

lIS speci1led on programmer Il'I9tnJction sheet

T2

I

necl the high voltage electrode (Fig, 83) to the ignition

eleCtrode on the gas pilot bomB! (The high voltaQEl eleC­

trode may be a qulck-connect type, or it may have a

threaded lerminal nut, depending on the model of the

0624A.) Use Honeywell Spec No R1061012 Ignition ca­

ble or eq.Jivalen1 (This wire is raled at 350 F [1T5 CJ for

~ .FEGu RO ,,.SIDE Qil

8 TER"" ITR" o~ ",R'NG ~VB8"'~[

& vS[ NH <l"'~l I "'Ill'"'' ,,,

FIG B5- 0624A CONNECTIONS TO AN

RAB90G, R4795, R4126, OR R4127 FLAME SAFEGUARD CONTROL

n l FEGVAIIO 'N~'O[ Q62

C"'''TRD'

_I",,.01l0N TEll"'"'''' O' F,A"E ~AF£"v"'''o

CONTROL SEE .O , TE ,,,STRun,o,, SHEET 'Oil HR"'I"A' OE~'G"AT'ON

& TERM'N"'L ITRIP DR ""RI ~uBB

& VSE Ie ." , ""RING "

FIG 86- Q624A CONNECTIONS TO AN R4140 OR

R4150 FLAME SAFEGUARD CONTROL

continuous duty, and up to 500 F 1260 C] for intermittent use 11 has been tested t02S.ooo volts.) The ignition caDle should not exceed 15 reel [4.6 metres] in length,

CHECKOUT OF THE QS24A Aner Ihe Q624A installation has been compleled, the fol1owinQ checks should be made to ensure that the sys­lem is working pr~rly

IGNITION SPARK RESPONSE TEST The flame relay shOuld not respond lDull in) 10 ignition spark To determine flame detector sensitivity to ignition

spark per10rm the following steps:

1 Shut off lhe fuel suj:pJy to Ihe pilot and main fuel valve(s) manually

2 Slart the SYSlem f:7.j raising the controller set point or

3 Energize lhe Q624A Sofid State Spark Generator so

an ig1ition spark Is produCed between Ihe eleclrode and ground

4 Check to be sure that ignition has nol occurred rrttere should be no flame.) Repeal steps 1 through 3 until Ihere is no 1lame

5 Check the flams relay on Ihe flame saf~rd con­trol 11 the relay has not pulled In the system is ~ralirlQ

prc:perly Continue the cheCkout with the Pilot Turndown Test

6 It the flame relay pUlis in, stop Ihe system, r~ace

the Q6.24A and repeat steps 2 through 5

260

REMOTE RESET ASSEMBLIES - - - ­

11110Z11 (FOA AA.,o's A,NO A.7n·Sf

\187018

(FOA A.I'O·S)

11876011 (FOA A.l.0'S)

7 Ilihe flame relay pulls in after replacing the Q624A,

stop the system, replace the flame safeguard control, and

repeat steps 2 through 5

o - 8 If the flame relay pulls in after replacing the name

saf8QUard control, Contact the local Honeywell branch

office

Remole reset assemblies provide the capability of re­

selting the lockout (safety) switch in flame saleguard con­

trols from a remote location All example of this awlication

'IS where the flame safeg.Jard control is located on an inac­

cessible roof or suspended from a ceiling with no catwalk

AIlother example is where the ftalT\El safeguard control is

mounted in an explosion-proot enClosure; the housing is

secured by many bolts In all of these awlications, it is dif­

licult to gel allhe resel buttQ1 on the 11ame safeguard can·

lrol so the ability to remotely r9S9t lhe lockout switch is

highly desirable

Some insurance agencies and code bodies severely

restricllhe use 01 remale reset assemblies, If there is any

question, these aulhorities should be consulted prior to in­

stallation of the reset assemblies,

REMOTE RESET COVERS

Remote reset covers are heavy dUty metal covers with

a remole reset assembly mounted 011 them The cover fits

over the flame safeguard control The remote reset as­

semtJly consists of a 120 Vall, 60 Hz solenoid, with a plunger Ihat is direCtly ali ,-,ed with the (esel bullon Q11he ftalT\El safeguard control Connecled to the solenoid is a 17 inch [430 mm] length of 2-wire, flexible Conduit, plus 19 inches [480 mm] 01 exposed, insulated leadwires Longer wires, spliCed to these 2 wires, are connected 10 a remote PUSh-bulton switCh, Pressing the push-bu!lon switch ener­gizes the solenoid and activates the plunger, The plunger awlies pressure to the reset bullon on the flame sale­guard control to reset the lockout (safely) switch Flemote reset covers available are shown in Fig, 87, Honeywell part numbers are:

118701 a-for use on R4150 Flame Safeguard Pro­gramming Controls

118702B-1or use on RA890 and R4795 Flame sate­guard Primary Controls

198365A-for use on R7795 Flame Safeguard Primary Controls,

118760B-for use on R4140 Flame safeg.Jard Pro­gramming Controls

PILOT TURNDOWN TEST Refer 10 the flame safeguard control )nslnJclion sheel tor the exact procedure to be used in performing the pilot lurndown test

FINAL CHECKOUT After other checks have been completed, restore the system to normal operation and ooserve at least one com­plete cycle fo be sure of satisfactory burner operation

FIG 87-REMOTE RESET COVE-FIS

To Install a remote reset CO'll8r, loosen the screw(s) in

the old cover llf there Is one) and remove It Allgl the sola-­

noid plunger In the new cover with the reset button on the

flame safeQ.JlHd control, and mounllhe cover Make sure

there !tiar leasl 1/4 Inch 16.5 mmj clearance 101" the

plunger Then tighten the cover screw(s)

AI the deSired remOle location mount a momentary

push-bullon swilch The switch must be rated to carry at

least 15 VA Ohe power qonsu~ion of the remote reset

solenoi9) Connecl the push.outton swilch 10 lhe solenoid

(Fig 88) Do notUS&8 toggleswiteh; if laft in the "on" posi·

tion II wguld cause the lockout switch to remain in the

"open" posilion The solenoid plunger of the remote resel

assembly must disengage from the reset bullon on the

flame safeguard conirol In order for the lockout sWitch to

ee>rTWlete the circuli inside the control

& PRO.,O' 0"~ONN'C1 ",AN, ANOOV'R~OAOPRonc·~,,~ ""' I

A' RH ".O

In '0T< "Un 00"< 0'0" _TEO A ' " VA

In "0 ", A' O"'R<O ~, O "oLAno"

FIG 88- TYPICAL HOOKUP OF A REMOTE

RESET ASSEMBLY

If addilional wire is needed to reach the push'bullon

switch, splice it 10 the 2leadwires exlending from the flex­

Ible conduit on the reset assembly (Fig B7) Moisture-ra-­

siSlanl No '4 wire suilablefor atleasf 167 F [75 C) If used

with an RA8900r R4795 , or for all~1194 F 190 C] if used

with an R4140 or R4150, is recommended for normal

installations

The lockout switch can be reset right al the flame safe­

guard control by pressing the end of the solenoid plunger,

or it CM be reselfrom lhe remole localion by presslnljlhe

remOle push-bullcn switch

REMOTE RESET ASSEMBLY (PART NO

118811A) FOR AN R4138C OR 0

This remote Jeset a.ssenbly Is very similar to the as­

sembly used 011 Ihe ramote reset covers, except thai II

does not have a flexible conduit around its leadwlres and

It has asolenoid arm (Fig 90) which depresses lhe JoC~oul

swllch reset bUIlDl'l on the R4138when the solenoid Is en­

ergiZed To mount the remole reset assembly on an

R4138C or D Induslrial Flame safeguard Control, insert

262

the nut and washer 00 the remote reset assembly Into lhe hole in the chassis just below the loc~out switch on the R4138 (Fig 89) Make sure the washer engages lhe Inside lip of the hole Slide the remote reset assembly upward (as shown by the arrow) as far as it will go Insert the mounllng screw and tIghten It securely (Fig 90) Make sure there is a minimum of 1/4 Inch [6.5 rTVTI] clearance between the sole­noid arm and the lockout switch reset bullon when the lockout swilcn is reset Wiring and q:'lEIration 01 this assam· biy is the same as for the remote reset covers (Fig 68)

"ESU BUTTON

~O:~oJl

J';l! -SOLENOIO A

RESET ASSEMBLV

SOLENOID

' - - - W ' R E {2_(lLACKI

LFIG 90-A '18811A REMOTE RESET ASSEMBLY

INSTALLED

INTRODUCTION - - - ­

A Flame safeguard System inclu~ all controls and

associated de~ces r8QJired far safe corrbustlon 01 the

lh(ee elements required for corroustion -fuel, air, and ig­

nition-fuel is the easiest to control

The purpose 01 the valve train, then, is to control the

flow of fuel into a combustion chamber so Ihal it burns

evenly_ Even combustion conserves fuel, controls pollut­

ant by-.producls, and provides the right amount of heal

needed for the process

In addition many ~roval bodies such as Underwrit­ers L aOOrator(es Inc., Factory Mufual (FMj, and Factory in­suranCe Association (EI.A.) issue co::ies for burning fuel safely

In this section, we will COYer the types of valves avail­able and develop typical valva trains to be used in Flame safeguard Systems

TYPES OF V A L V E S - - - ­

There are four types of valves used with ffame safe­

guard equipment They are the Manually Operated Valve

or the Automatic Solenoid Diaphragm, and Motorized

MANUALLY OPERATED VALVES

Although most valva trains reqJlra automatic opera­

tion, the manual valve, Fig 2, still provides corwenianl fuel

shutoff for temporary maintenance or service

Manual shutoff valves are used in oolh the main and pi­

lot fuel lines This valve is also called a plug cock because

263

it consists of a tapered plug with a horizontal opening As thEi manually operated handle turns thEi plug, gas llows through the opening

A V5050A FUElI Cock is anElIElclrically interlocking plug cock

The V5060A, Fig 3, has two internal1nterlock switches that are connEicted to the Flame safeguard Car'llrol and sa1ely Shutoff Valve These switches prEivent ignition of the pilot if thEi V5060A Valve is open AflEir thEi pilot is ig­nited, the V5D60A may be manually cpaned to light the main burner

ArlolhEir type of valvEi is the Manual Reset safety Shut­off Va)~e commonly called a Free-hardle Valve This valvEi closes automatically in response to Ihe Flame safe­guard Controt, but must be opened by hand An electrical circuit holds the valve open but cannot open it by itself Af­ter thEi circuil is ElnEirgized, IhEi valve is ~by hand and remains open until tl"lEl circull is de-energized This

PLUG COCK MANUAL SHUTOFF VALVE

71-97558-1

V5060A SUPERVISORY FUEL COCK

FIG 3-VS060A SUPERVISORY FUEL COCK

Free Handle Val e is used as the safety shutoff valve only

In manually ignited systems where the burner is seldom

shul down

AUTOMATIC VALVES

SOLENOiD VALVES

Of the three automatic valves the Solenoid is the sim­

plest and generally lhe least 8lCpensiv8 A controller opens

the valve by running an electric current through a mag­

netic coil, Fig 4.lh6 coil, ac1lng as a magnet, pulls up the

valve disc and allows the gas or oil 10 flow Solenoid action

provides fasl CIp!:lning and closing limes, usually less than

one second in models wilhoul a thermistor delay

shutoff valves in gas pilollines The V8036 or V4Q36, Fig

S, is used in the main lines of smaJJ to maoum gas sys

lems Unlike Diaphragm or Motorized Valves, the Soler

noid is also used in ,:,il burning systems Use a V4046A,B

FIG S-V4Q36N8036 SOLENOID VALVES

for no heavier than No 2 oil; and use a V4021A for heavy

oil <lWlicallons ALL of lhese are Solanoid valves DIAPHRAGM VALVES

Diaphragm Valves, like the DrI8 Shown in Fig 6, are generally used on atmosph&ric typeo gas burners 10r smooth lightoN These valves have a slow opening and

last closing lime which deperdi on the amount of gas flowing over the diaphragTl

ThQ valve consists 0' a diachraam wifh a weiQ!l( over the valve seal A small inlernal solenoid valve blocks the gas flow 10 lhe bleed port

When the COn/roJlef is not camnglor heat, Fig 7, the Coil

is de energized The plunger in the three-way actuator is

In lhe DOWN position, 50 lhallhe bleed' port is closed and lhe supply port is opeM Gas 1l0'NS to the top 01 the dia· ohragm lhe gas pressure and the weight hold the valve closed

SLOW OPENING-FAST CL.OSING USED ON ATMOSPHERIC GAS BURNERS

V480R vsa

~v~ 113-7

FIG 6-V48/88 AND V4843/B843 DIAPHRAGM

71-97558-1

264

PLUNGER WEIGHT DIAPHRAGM

VL~~~ :-::::: -~=~:::==r-live &3-1

FIG 7-S0LENOID VALVE - CLOSED

On a call lor heat, Fig 8 Ihe controller contacts close and the coil is energized This pulls the plunger to the UP p:>silion, opening the bleed port and closing the sl lWly port The Qas then bleeds off the lcp at the diaphragm, al­

lowing Ihe Qas pressure 'Qeiow \0 lift the diaphragm and

open the val "'e

When aillhe Qas has bled off the lop of the diaphragn, Ihe valve is fully q::lEln, FIg 9, permitting gas flow to Ihe main burner

After 1M controllar is satisfied, the proceclJre is re­

versed The controller contacts open so Ihal the coil is de­

-,'

energiZed The plunger is released, moving \0 the DOWN p:>silion, FiQ 10 This closes lhebleed pan and q::lBns the sUJ)ply port so that gas at;tain flows to the lop at the dia·

PLUNGER WEIGHT OIAPHRAGM

FIG a-SOLENOIO VALVE - OPENING

snap acllon

Diaphragm 't/al't/85 are CJ,liet ard ha't/(1 a reasonably long life They are generally less expensi't/e than motor· ized 't/al't/85

Another ~ 01 diaphragm gas 't/al't/e is the COI'T"biM' tion 't/alve (Fig 11) The basic q::l9falion of this If8I't/e is the same as already dBscrlbed, except thai it adds (or corn­

billB5) other f\.lnctlons into one 't/al'tle txxly The V484JIV6843B,C.L,N Valve Incorporales a single stage pt8S8U1'8 regJrator into the basic dlaphraQTi 't/al't/(1 desigl The V4844/V8844B.C,L, N models pro't/lde two stage pres­sure reg.rlation The one or two slages 0' pressure reg.rla­tion are used fa prO'ollde one or two staQ31iring rale control

to the burner system The V4843I\I8843P Val't/9 pro't/lde5

a intermittent pilol takeoff port

FIG 11-V4843fV8843 AND V4844fV8844

COMBJNATION DIAPHRAGM VALVES

MOTORIZED VALVES

Motorized valves perform two runclions-satety shut­

off and firinQ rale control We will discuss each 01 the fUnc­

tions separately

SAFETY SHUTOFF 'vALVES

Safely shutoff valves are usad for large gas burners

Ihat require:

1 tighl closeoff

2 accurate control of large MlOUnls 01 fuel

The Honeywell family 01 Safety Shutoff Valves \s shown

The V4Q55 actuator contains only a dump valve for ON­OFF cp9ralion The 1/4062 OFF-lO-HI actualor and V9055 mcd; dating actuator, FiQ 11" alse contain a bieed valve to control Ihe amount of gas flowing to the burner The bleed valve contrds the valve stem travel stanlng at the low fire position, and continuos 10 cperate only when lhe aclualor is driving the valve cpen

Valva actuatols have 2 cpenlng tirnes-13 and 26 sec­onds Models with 26 second limi"g have a small molar and Ol"lly 1 pIston in lhepu~ MOdels with 13 sec()(Xj lim­ing have a large motor and 2 piston pumps

The different kinds of V5055 valves are shown in Rg

12 The VSQ55D,E are used for high pressure applica· tions, while V5055A·C are for low pressure appllca:ions Nole that the V4055 ON-OFF aCluator may be used with any varve The V4062 OFF·LO·HI and the V9055 modulating valves must be used only on the v5055B with a

V40SSA WITH VSOSSA

INDICATION

VAlVE "SHUT"' INOICATION

••G" "

FIG f3-CUTAWAY VIEW OF AV4055A WITH A

V5055A

V4062 AND V9055 PUMP MOTOR ANO DUMP VAlVE ASSEMBlY

T f4E ON 0"" V40~5 HAS A DUMP VAlVE ONl V-NO BlEED VAlVE

PUMP MOTOR

Bl E, 0 VA.lVE

OU"'P VAlVE

OUMP VAlVE SOlENOIO

FIG 14-INTERNAL VIEW OF V4062 OR V9055

A Characterized Guide (or skirted gJidel Ag 15 has notches or V's cut into lhe gJide to determine the valve flow characteristics II provides a predictable relationship between stem travel and gas flow

As the valve varies the fuel, a c:lalTp3r linked to the valve actuator varies the corrbJstlon air In this way the valve ar1d actuator control both the fuel and air noodecl to vary the burner firing rate The V4062N50SSB and the V9055,iV5055B seNe a dual purpose as safely Shutoff Valve and Firing Rate Control

These combinations may only be used on alm0scherlc burners where codes allow a dual fUr1ction 't'2tlve For other applications a Bullerfly Valve IS used whiCh will be dis­

cussed laler

CHARACTERIZED GUIDE

FIG 15-A CHARACTERIZED GUIDE The V5055C,E valves reQlJire a valve seal overtravel in­

terlock (Fig 16) 10 make sure the main fuel valve is closac! before allowir1g lhe ignition sequence to start To accom­plish this, the V5055C,E valve with two seals is used with a valve-closed indication switch on tne valve actuator The

~ switch can be wired to either make or break a circuit when the valve is in the closed position,

VSOSSC, E

VALVE SEAL OVERTRAVEL INTERLOCK

"SHUT"" Ols.::

JUST PP.lOA TO STANDARD SEAl ClOSING

Io':",,~ ElOTH VALVE SEALS ARE CLOSED

sPECIAL VALVE SEAL

ON VS05SC AND EONLY _~ SWITCH IN ACTUATES

FIG 16-V5055C,E VALVE SEAL OVER

TRAVEL INTERLOCK

As lhe valve closes, the ~r seal CID8eS fi",t, step­

ping the gas flow The valve stem musl ·overtraveJ-pas! this point before lhe switch closes Fir1ally the lower seal Is closed

The switch Is normally wired ir1to Ihe • Preignition Inter­lock· circuit at the Flame sa~rd Control to prevent ig­nilion unless the valve is ·proved- to be closed

FIRING RATE (BUTIEAFLY) VALVES (FIGS 17 AND 161

By controlling the amount of fuel entering the bJrnaC this valve determines the rale of combustion, or fIrlng rata

71-9755&1

VALVE

_ _ _ CRANK ARM

:; -DFlIVE PIN

STRAI'l RELEASE SPRI'lGS 121

ACTUATING ARM

AI the same time, the valve actuator controls a damper

which, in turn, controls the flow of combustion air 10 the

burner

FIRING RATE

VALVE

COtlTROLS CO"8USTION

PLATE

Oyo " ""

FIG 18-V51E BUTTERFLY VALVE

Other names for the cord)inalion firing rate valve and

actualor are: Burner-ll'l)Ut Control Valve, Combustion

Control Valve, MeterillQ Valve, Modulating Valve, Operat­

illQ Valve, and ThrotWIlQ Valve

As mentioned be1ore, the V9055/V5055 Modulating

Safely Shutoff Valve may be used fOf Ihis p,Jrpose, but be­

C8Ll!ie mosl applications rBqJire single function valves,

lhe V51E Butterfly Valve (Fig HI) is mosl ofIen used The

V51E is combined with an M941 actuator and 0100 link·

age Since the V51 E Butter1ly Valve 00es not closetlghUy,

a separate safely shutoff valve must be provided

The BL/tler1Jy Valve is named aner Its rOlaling hinged

plata that reserrbles the opened wings 01 a butter1ly This

valve has a hiQh flow capaCity and relatively constant rela­

liDnShip between fuel110w and the angle of alve ~illQ

(Flg 19) This feature IS useful for close modulation of air

and fuel gases '0 large furnaces An M941 Modulrol Ac­tuator (Fig 20) controls the valve While simultaneously 0p­

erating a corrbuslion air damper Together, the valve and actuator provide a stable mixture of air and fuel

As the controller energiZes the M941 actuator, the in­creased resistance unbalances the molor bridge circuil

To correct the unbalance, the motor drives the linkage to rotale the hinged plate on the V51 E and open the Butter1ly Valve The actuator continues to drive open until its feed­back potentiometer moves to rebalance the circuit and stop Ihe motor

VALVE OPENING ANGLE DIRECTLY RELATED TO GAS FLOW

oyO" "

FIG 19-VAlVE OPENING ANGLE IS DIRECTLY

RElATED TO GAS FLOW

FIRINGRATf

FIG 20-M941 MODUTROl MOTOR

71·97558-1

268

VALVE T R A I N S - - - ­

In this $eclion, we '1'111 davelcp a typical gas and oil

valve lrain used in a Flame SafElQU3rd System For spe­

cific information on valv9 trains approved by various ap­

proval bodias, see the Recommet'ldad Valve Trains

setticn

GAS' VALVE TRAINS

BAsIC COMPONENTS

~ shown in Fig 21, the first and most Ilasic cDlT'PO­

nenl Is the pipe, or gas line used to carry gas to the com­

bustion chamber

The gas .111 nol be Mowing continuously throu'tt!lhe

pipe, 50 we need a manual plug cock to !urn the gas on or

off t:If hand Tl'1is plug cock is called thE! Manual Shutoff

Valve (MSQVj

In a basic manual 1i{j110tf system lhe operator ius!

turns on the MSOV to start the gas r10Wlng into the com­

bustion charrber Then, he throws in a lighted match, rag

or piece of paper and stands back as the gas bursts Into

Ilames

However, most applica(ions Icday reqUire a smoother,

safer lightaff So, we will acid a smaller pipe, the pilot line

(FiQ 22) An MSOV is required in the pilot iine, too

When ttIe puot flame is going, the main MSOV Is cpened The pllolflame lights the main gas as SOClf1 as It Erlters the ccmbuStion char'nl:ler

This manLli'lllightolf syslem works well as long as a per­son constantly watct'es the name If the flame lJ)9S out

ciJe 10 a pil (;03d gas line or some other undasirabJa occur­

rence, he can close the valves and shul eXIwn the t;)Jrner HO'l¥ever, it he does nol notice a name out siluatlon im­mediately, the cOl'TbJ:stion chan1:ler wilf nlf wilh urbJrned gas lhe urbJrned gas, of course, creates a very danger­ous situation when the burner is rei(1lited

So, to walch over the flame, we need an automatic flame safeguard system wilhin the valve train Our firsl corrpanent is a Safety Shuloff Valve (SSOV), FiQ 23, 10

II~

•

SAFETY SHUTOFF VALVE

FIG 23-SAFETY SHUTOFF VALVE (SSOV.)

automatically lurn the gas on and off

Notice tNt the syrrtJol used in Fig 24 has a mile block above it This block represenls the actuator

We will also wanl a SSOV in the pilolline

Something musllell the Safety Shutoff Valve when to open and close the gas line This is a logiC panel which In­etudes the Flame SatE9JSJd Control Tnis conlrol is the heart Of the Flame Safeguard System, Fig 25 Usually,

the panel is located on the wall, a few feet from the valve Iraln and the corrtlusllon charrber It could also be mounted ri~t on the boiler

We also need a Flame Deleclor (FIg 26) 10 walCtl for a flame in !he corrt:lustion charrber

Now, to start the burner with our automatic valve train

we first open both the Manual Shutoff Valves Then, when

we need heat, the Flame Safeguard Control q:e1S the Safety Shutoff Valve iJ"lthe Plio! Une At the same lime, it turns on an ignitioJ"l sci-uce for the pilot, Fig Zl

Wh8l'1 the flame detector sees the pilot flame, 1\ tells (he Flame Safeguard" Contralto ~n lhe Safely Shutoff Valve

In the lllain burner line The pilol then 1i~IS the main burner, Fig 28

Once the main burner Is lit, we can Jeavethe pilot on or lurn il off If (he pilot remains burning while the main burn­

system, the Flame Safeguard Control Signals (he pllol SSOV to close the gas line once the flame detector has proved the main burner name

If bolh the pilot and main flame go out (Fig 29), the

ttame delector will break ils clrcuillo the Flame safeguard Control The Flame Sa1eglJafd Control, in tum, will signal

FIG 25-THE FSG CONTROL IS THE HEART OF

THE FlAME SAFEGUARO SYSTEM

FIG 26-THE FLAME DETECTOR WATCHES

FOR A FLAME

both pilot and main SSOV's to stq:l gas now This is the Safety Shutoff Circuit

UI"BU~"O~ C~"·",.

CIRCUIT

AvO " , SSOV PILOT LINE

COM8USTION CHAMBER

FIG 29-SAFETY SHUTOFF

Another point we must consider is providing gas to the

burner at [he right pressure, Fig 30 Gas enters Ihe valve

train at a pressure as hio;j1 as 10 pounds per sqJare inch

Unfor1unately, gas at this pressure cannol mix properly

with air and p:JOr combustion results For proper combus­

tion, a typical pressure is 4 inches we or only 0.15

psI-This means thatlhe valve train must deCrease the pres­

sure considerably So we will aoo a Pressure Regulating

Valve (PRVl as shown in Fig 31 The ut=P€!r pan 01 the

'RV

SYMBOL

FIG 31-A PRESSURE REGULATOR VALVE

PRY symbol is an oval, representing the diaphragm in the

PRY

Since we want 1:1e PRY to cuI down the pressure, we

will locate it upstream of the SSOV in both the main and

pilot tinas, Fig 32 The raduced pressure Increases the ef­

ficiency and life 01 the SSOV

Iryou compare the 110w orgas 10 the flow of a river, VOU

can see why this location is called upstream If we located

the PRV on the other side 01 the SSOV, It would be cbYvn­

Now we have an autOlT'l8l1c 5VS18m for lighllng the pilot and main burner

SAFETY SHUTOFF REQUIREMENTS Under normal conditions, our automatic system should safelV light the plio! ana main burners, prOViding tha,tthe SSOV Cbes not leak Unfortunately any valve can leak Slio;j1tly if the seat does not closs perfectly So i1 we shut down our automatlc valve train ror the weekend, a sli~

amount 01 gas may leak through the SSOV and continue past the open MSOV into the burner Remember, since this is an automatic system the MSQV will be left open

When we start the burner up on Monday morning, we may have an explosion due to a combustion charrber fiJI! of un­

To eliminate any gas leakage proolem, we need a

blower (Fig 33) 10 get rid of any accumulated urburned

MSOV "'v S$OV

FIG 33-A BLOWER GETS RIO OF

ACCUMULATED, UNBURNEO GAS

gas before we light the burner The motor which drives the blower is usually called a burner motor Now Iilring slarh p, the flame safeg.lard control Si\T.als the blower to blow air Ihrouo;j1the cOl'Tt1uStion charrber ana clear oul the gas This is called purging

To purge the con1JustlOl charrber 01 all urtx.nned gas,

we should use about 4 changes of air That is, we should blow through about 4 limes the volume of air that the can­

71-97558-1

ouslion charTbar holds 1lle tIame safEQJard control limes

the purging procass to provide 4 changes of air

Purging gets rid of the gas leakage danger at li~toff,

but doeS nothing 10 prevent the accumulation of urtlumec:I

gas If.we add a second SSOV (Fig 34), 2 valves would

."" uiO

have 10 leak al lhe same lime to create a problem

For more protection, we can add anolher pipe (Fig 35)

between the 2 SSOV's leading to the outside air An auto­

matic vent valve is then aQjed (0 vent any leaking gas

while the SSOV's are closed While the SSOV's are q;>en

and gas is nowin.g to the Dlrner, the vent valve is closed

This valve arrangement Is called Doutie·Block-and·

Bleed (Fig 36) While the burrler IS shul oown, any gas that

leaks pasl the first Safety Shutoff Valve will escape, or

"tieed Off, w to the oulside atmosphere through the Vent

FIG 36-DOUBLE·BLOCK·AND-BLEED,

Valve The second Safety Shutoff Valve, Just cbwnstream

from IheVent Valve will bloCk atT'fgas which is not vented With lhe combusllon chamber also vented to the al· mosphere through its exhaust sy.stem, there will be no pressure cJi1terence across the second SSOV Fig 37 So

and is recp Jired tly some approval bodies

GAS PRESSURE CONTROL Our system is still not cOll'flletelysate What if our Pres­sure Regulating Valve falls? Gas at pressures up 10 10 psi could enter the combustiOn chamber, There will be 100 much gas tor the combustion air available, and the flame will go out

71-97558·'

We will be left with a fuel-rich mixture (Fig 38) in the

combustion chamber, a &ituaflon thai 1& alway& very dan­

gerous But, as condltions sland, the milliure cannot be ig­

nited because thera Is 100 much gas for the air available

But air does come Inlo the cart:lu:stlcn charrt:Jer natu­

rally (due fo atmospheric pressure) Of mechanIcally ~1t"Q

forced In through purglng)_ Finally when enough air en­

fers to create a mixture that can be i(7lited by a very low

ener.m' source, the concentrated fuel-air mixture ex·

plooes, (Fig: ~)

, lOPS''''

FIG 38-FAILED PRV = FUEL-RICH MIXTURE

To stop this situation, we need a High Pr855ure Switch

to notify lhe Flame safeguard Control to shut down the

system The High Pressure Switch samples the gas pres·

sure and open& an eleclrical circuit iflhe pressure rises

past some preset level This swilch never blocks the gas

flow, it just taps into the line to sample the pressure

We should locale this switch near the burner (Fig 40)

since we want to keep the gas pressure at the burner

within the limits for proper corrt:ostion For this reason,

the High Pressure Switch is often callecl a High Uml!

The High Pr86SUre Switch should be installed just up­

stream of the Manual Shutoff Valve In most valve trains,

the Manual Shutoff Valve should CornEl last, so we can

shut off the burner but still have gas available for checking

lhe olher ~alves and switches

We can let the burner restart automatically when the

pressure returns to normal Or we can r8CJllre someone to

push a button on the High Pressure Switch before the

burner can be started again This is called Manual Reset

With Manual Reset someone is going 10 notice that

something Is wrong Usually the q)ElratOf will correct the

So we need a Low Pressure Switch or low Limit to sig­nal the Flame safeguard Control when the pressure falls

to a preset level The best pressure sampling locatioo is with the High Pressure Switch right next to the burner (Fig 41) However, with our low Pressure Switch downstream

of the Safety Shutoff Valves, the switch will be sensing zero pressure when the burner is not running and the Safety Shuloff Valves are closed With this location on a manual reset system we will have to push the button every time we want to start the burner

So, our Low Pr855ure Switch should be moved up­stream at both safely Shutoff Valves (Fig 42) Now we have 2 pressure switches 10 keep us within our limits tor

sale burner c:peration

As we mentioned before the Manual Shutoff Valve is the last controt in the main gas tine, so we can lahul off the gas SlJR)ly to the burner, but still have gas available tor checking lhe olher valves and switches But, if we need to replace a valve, how do we shu! off the gas? We need an­

FIRING RATE VALVE

CONTROL OF GAS FLOW

The Firing Rate Valve (Fig 4.lI) is no! really necessary to

the safety of lhe valve train, but it provides a convenient

methOO of controllit'lg the flow of fuel

The valve should be placed close to the burner to get

lhe best oontrol In sorr'Ie valve trains, you will see lhe Fir­

ing Rate Valve located just atter fhe second SSOV and

ahead 01 the Hi'lt1 Pressure Switch In other trains, the

valve will be downstream or lhe PRV and upstream of the

Low Pressure Switch The preferred location is near the

burner (Fig 45)

Thai completes the schematic or our valve train Now

this is what an actual gas valve train looks like (Fig 46)

Here is the end 01 the combustion chamber, showing

Ihe complete valve train Notice how much smaller lhe

pipes are in the Pilot Une than in lhe Main Burner Une The

straight through the whole combustion chamber This

photo also ShOws lhe location of the Flame Deteclor This

deteclor is a Honeywell C7012E Purple Peeper Ultraviolet

Flame Detector The C7012E Is colored violet to indicate it

is an ultraviolet detector

274

CO BUSTIOIIi CHAMBER

FIG 46-THE COMPLETED VALVE TRAtN Fig 47 shows the logic panel, which includes a Flame

Safeguard Conlrol -Ihe hear1 ollhe system Nolice the in­ dicating lamps which show the status of the system

71-97558"