flame safeguard control phần 7 pps

WarcI make R to B when the conlrollEld variable falls 10 the sat point minus the differential. A controller w!lh an additive differentIal operates simi- larty e.~CBpt that the set point is al the/ow end of the differ- enliallnslBad at at the hiQh erd. A controller with manual reset (also callEld lockout) can beUMd as a limltta (1) shut down the System it it braaks a Circuit or (2) ~rate an atarm It makes a circuit On most CCJ1lrol1e~ wilh manual reset, lockout occurs at the sat point, but on a few rT'l(XjeIS it occurs at the sel point plusor minus-the differenlia.!'. The circuli will stay lockEld out until the ternperaturereturns. 10 normal (lockout point plus or minus the diNerenllaQ and the ~rator depresses a manual rese! rever or button (Fig. 2 or 48). It the lever or bullon has a trip-free feature, operation will not be returned 10 ,. ' ' - - - ~~T S~OT - - - SRE~K M~KE RE~~"'·6. ~E "'.W - I ~ - - - '0'""" 0. , - ) 0"""'"'' ! - - J ~~"T+_ F-I.!!!L KE .IlE~K RE KR fol~KE R-II - - - - ~==-=~ FIG.8- OIFFERENTIAL FOR ON-OFF CONTROLLERS. normal until the manual reset lever or button Is released. This prevents the COfltrolier from resetting automatically, even if the manual reset lever or button is IiEld down or held in by tape, wire, or some other device. Manual reset makes sure someone is going to notice 6Ol1l8thing is wrong. A good servica lechnician will correcllhe prOOIAf11 before reselling the switch. PROPORTIONING RANGE Tha proportiOning range (also caliEld Ihrottling range usually edends above the set poim (Fig. 9). alihOugh Qrl some controllers it extends on lxlth sides 01 the set point. Pressure or temperature variations cause the bellows or diaphragm to move, caUSing the potentiometer Wiper (R lerminall to move across its windings. This varies lhe re- sistanCe between R and B, and Rand W. The resu1ting circuit urtJalance drives a modulating motor or mod:.JlalinQ valve aCtuator and regulates the firing rale. (For a detailed explanation of this operation, refer to the Flame Safeguard Reference on Firing Rale Controls, 10rm 70-8117.) As the controliEld variable rises, the Wiper will move toward the W end of lhe potentiometer, driving the motor or actuator toward its Closed position ard decraasing the firing rate. As lhe controliEld variable talis, lhe wiper will move 'award the B end, driving the motor or actuator toward its open position and increasing the firing rate. Thus, a CharlQ8 in the controllEld variable wilt cause modulation of the firing rate 10 compensate for fhe Change and keep the pressure or terrperalure nearly CQrlstanl. t , -co ,,,. B,, r-> IClO§W) I I T ~"'OPOR I ( POTENT'O"UER T'ON'NG Ii::, "''''lOG' (",~~;j] : : -NIGNFlIlE 10'ENI 5h PO'''' +1'-Ol.L-~ L - + • J & ON A'£>O CtlfITROlU"" (:weH "" THE TN' n"'ER",TURE [Or<TAOl· lEftSl. THE k~ PO,,""" 'IT TNt. Cl TU OF?tt:. 0""0 ' ' ""' E_ ill SQ"f C","'ROlLEIl' (SUC" "S 1HE T1"0 TEM.E" W"E COHfIlOl· LUI VE z POTEHTlO"Uf'lll OI"l:"''''T'''' IN UN'IoO". FIG. 9- PROPORTIONING RANGE FOR PROPORTIONING CONTROLLERS. 220 On some controllers. the proportioning range is 1ixed, while on others it is adjustable. On adjustable models, the proportioning range scale is usually graduated tram A to F .'!yith. a MIN (minimum) value below A. The value of each division depends on the cperaling raf1Q8 and set J,)Oint at the controller. Proportionlng range charts like the one shown in Fig. 10) are available for different cperaling ranges to determine the pr~ seuing. (The propor· tioningrange scales of some t~ralure controllers, like the T991A ~d B, are marked directly in degrees For q. M'N'" • , 0 • • \ \ , "'OlO"? & rll.""RUU"l ' • 1\ , I'~ \ 1\ 1\ \. 1\ " \ , 1\ 1'- , ". • ,. . ~ . , ~ . , , '''01'O''T10''''«;' Cl alCRUS F & FOR LOW n"PlfLl,TURl VAPOR_.RlUURl SENS''''' ELlMl n (T'" COH?f'OLLl"'l FIG. 10- TYPICAL PROPORTIONING RANGE CHART FOR A CONTROLLER'WITH AN AOJUSTABLE PROPORTIONING RANGE. CHECKOUT AND MAINTENANCE CHECKOUT After the controller has been installed, wired, and set, it should be tested with the system in operation. First allow the system to stabilize. Then observe the operation of the controller while raising and lowering its set point. Pressure or temperature should increase when the set point is raised and decrease when the SElt point is lowered. Use accurate pressure Of tef'11)erature testing equipment when checking out the controller. Do nOI rely on inexpen· sive gauges. For an on·off controller. make sure the swilch makes and breaks at the proper points. Be sure to consider the differential. If the controller is ~£1ad ol operatinglffi- properly, it may be further checked as lollows: ,. Disconrlect the wires from the controller. 2. Connect an ohmmeter between the switch terminals. 3. Raise the set J,)Oint of the controller more than the differential, The switch should either make or break, depenc:J. ing on the model of the controller. (11 it makes, the If a proportioning controller is suspected of operating ohmmeler will read zero; if it breaks, the ohmmeter will imprope~ly, it may be further cheCked as follows: read infinity.) 1. Disconnectlhe wires trom the cOf1troller. 4. Lower the set point of the controller more than the dif- 2. Connect an Ohmmelel between cOf1trolier terminals ferential. The switch shoold break or make, depending on 8 and W to measure the resistance at the potentiometer in its action in step 3. the controller. The Ohmmeter should read about 135 Ohms 5. An approximalion of the differential can be made by or 270 ohms, depending on the model 01 the controller. observing the change in set point r9QJired 10r a resistance 3. Conneclthe ohmmeter between cQnlroUer terminals change from zero to infinity. Wand R and raise the set point of the cOf1trolier above fhe For a proportioning con/roller. make sure the modulat- actual pressure Of' temperature being measured. The ing motor or modulating valve acluator reaches the low ohmmeter should read the full value of the J,)Otantiomeler and hiQh fire J,)Osilions at the proper points. If the motor or measured in step 2 (135 or 270 ohms). actuator runs in the proper direction when (he set point is 4. Slowly lower the set J,)Oint of the controller while 00- adjusted, il can be assumed that the controller is operating serving the ohmmeter reading. The resistance should properly. It it runs in the wrong direction, reverse the 8 a.nd drq) to zero at some sel point below the actual pressure or W wires. Observe the action of the motor or aCluator tosee temperature. if it stabilizes. If the motor or valve is moving cOf1stantly. 5. An approximation at the proportioning raf1lijJEl can bEl widen the proportioning raf1Q8 (if it is adjustable). a lillie at made by observing Ihe chaf1Q8 In set J,)Oint rElQUired tor a a time, unlil the system is stable. resistance change from zero to full value. 221 71·97558-1 CALIBRATION AU controllers are carefully tested and calibl"aled at the factory under controlled conditions. If the actual ~rating preslil,lr.es_ or terrperatures 00 not malch the set points, most controllers can be recallbrated in the field. FirSI slsl of occasional inspection and blowing or brushing away any accumulaled dirt and dust. To ensure prq:er functioning of lhe controller at all times, an ~raUona! check of the Mtire system Should be performecl wring routine maintenance checks. check lhat the controller is level (i1 it hasa mercuryswilCh). Ralevel il if necessary, and recheck the ~raling points. It there is still a discrepancy: 1. On 6Om8 controllers, the scaleplate can be moved slightly L;lP oroowQ u(\111 the sat point agrees with lhe actual pressUre 0( tef'rl)erature. 2. On other controllers, the set point Indicating dial can be turnecl with a special calibration wrench until it agrees wilh the actual pressure or terrperature. MAI~TENANCE The ,cover of the controller should be in place al all times to protect the internal components tram din, dust, and ~ysical damage. ROUline maint9l'lBnce should con- -,' Occasionally, mishandling of the controller may cause a malfunction. A gradual change Of control point may oc- cur because of a very small leak In the lhermal system. On temperalure controllers, this Is mosllikely to be causadby bending the capillary tubing too sharply, or too close to a joint. Aging althe factory would have revealed the leak if it had been presen1 at the lime of assembly. If/he tLbing is squeezed so hard or bent so Sharply that ils bore is com· pletely closed l,4), the controller will, of course, be ren- dered entirely in~ralive. Deforming the bulb (or Olher sensing element) will change the VOlume, resulting in a Shift in calibration. Tnese ~ of malfunctions should be lool<ed for ciJring maintenance. Controllers should be han- dlecl carefully althe time of installation, et.Jring actual use, and during mainlenance. 222 , .~ PRESSURE CONTROLLERS A pressure controller is a device thai monitors the pres- waler heating systems, In gas burner systems, and in oil sure of sleam, air, gases. or /iQ.lids. AA internal diaphragm burner systems. Honeywell pressure controllers available or bellows responds 10 pressure changes and, throu;j1 IS for use In these systems wltJ be described In (he following mechanical linkage, acluates a switch or polenllomeler to sections. Installation procedures peculiar to each system keep the pressure within predetermined limits. Pressure will also be diSCUSSed. controllers afe com~nly usaa' on steam boilers and hoi PflESSUFi"E CONTROLLERS USED ON STEAM BOILERS AND HOT WATER HEATING SYSTEMS The pressure controllers discussed in this section can be used with steam, air, noncombtJslib!e gases, or fluid noncorrosive 10 the pressure sensing element. They pro- vi~ operating control or limll protection, depending on the controller model al"d wiring hookup (Figs. 3-7/. LOCATION AND MOUNTING When used with sleam boilers, always mount the. controller above the water fine in the boilEir. A steam trap must always be connected between the controller and the boiler (Fig. 11) to prevent boiler scale and corrosive vapors from atlacking the diaphragm or bellows. The 1<::q:1 on the steam trap must always be perpendicular to the face of the controller. 11lhe f<::q:l is parallel to the contrOller, expansion or contraclion 01 the 1<::q:I will tip the controlier and cause the switch to operate inaccurately. The controlier can be mounted (1) alongside the pressure gauge, (2) in a filling on tile boiter provided by the manufacturer, or (3) at a remote location in case of exces· sive vibration. When making pipe conn&ctions, use pipe compound sparingly to seal tile joinlS. Excess pipe c0m- pound may clOQ Ille small hole in tile fitting al"d prevent the controller 1rom operating properly. ~"E55U"E , ,,,,~/~~O"TROLLER .""~~ • PIlESSOJII(. Zkl S7 10'A. RIGHT , T GAUGE , ."2 TO~"2 (1 a TO aOj WRONG .& l/O-'''C," BLACK 'RO" ~'~E WI'," ,/ ,a NPT [XTER l T f. OS Oil BOTH ENO~. , ,e BOILER FIG. 11- RIGHT AND WRONG MOUNTING OF A STEAM TRAP, WITH APPROXIMATE DIMENSIONS IN INCHES [MILLIMETRES IN BRACKETS]. NOTE: If using tile controller with a CO!T'Pressor, install a dampening device (wch as a needle valve. header, or surge lank) to dampen pulsations which can damage the controller or reduce its life. To mounllhe conlroller alongside the pressure gauge (Fig. 11), remove the gauge. In its place. install a steam trap with a lee on tap. Using elbows and pipe nipples, mount the controller and pressure gauge on the ends of Ihe tee. If it is not convenient to mount lhe controlier alongside the pressure gauge, install a steam trap in the fitting provided by the boiler manufacturer. If there is no 1ilting. mount the steam trap al a location recommended by the boiler manufacturer. Screw Ihe controller directly to Ine steam trap. If there is ex.cessive Vibration at the boiler that mayad- versely affact the operation of the controller, the controller should be mounted' at a remote location. All piping from the boiler must 'os suitable and solidly mounted. The piping must be properlV pitChed to drain all cOndensation back to the boiler. A steam trap must be mountEKl between the remote piping and the controller. HONEYWELL PRESSURE CONTROLLERS AVAILABLE FOR USE ON STEAM BOILERS AND HOT WATER HEA,TING SYSTEMS Honeywell pressU/8 controllers are fistEKl in Table II al the el"d 01 this section. along with their applications, switch types, al"d operating pressure ranges. Fig. 12 shows the mcx:lels IiSIEKl. AlIl'T'\Ode1s operate as desCribed in Basic Principles ot Controllers except the P455. which is a corrtJination prq:;ortioning al"d on-otf controller. lis operation is descri'osd next. For furttel infor- mation, refer to the instruction sheers tor the controllers. OPERATION OF THE P455 COMBINATION CONTROLLER The P455 is a combination prq:;ortioning al"d cn-otf pressure controller. [n addition to a prorortioning potentiometer, it has an spst swilCh with a subHacUve ditferenlial that breaks on pressure rise. Tha main scale is set at the manmum pressure desirEKl. The differential is adjustEKl in- stead of the prcportioning range. Tl"le proportioning tange will automatically be sat 10 approximately 85Percent of the differenlial. (The differential sca[ap1ale is graduated from A to F with a MIN value below A. Refer to the P455 instruction sheet for values 01 the differential and proportioning range.) 223 71-97558-' FIG. 12- HONEYWEll PRESSURE CONTROLLERS AVAILABLE FOR USE ON STEAM BOILERS MID HOT WATER HEATING SYSTEMS. '.' The P455 also has a UNISON/SEQUENCE adjust- ment, which provides a choice 01 firing rale at burner startl.P. The odjusling dial is located just below the wiper armof the potentiometer (Fig. 2?). The dial is turned so Ihe arrow is at Ufor unison q:)(lralibn, at S for sequence cpera· lion, or at one of 3 inlermediale positions, Fig. 13 sh(w,rs the operation at Ihe P455 for each of these p::lSitions. In (he UNISON position, Ihe prcportioning range is: entirely within Ihe differential range, so the on-ott swi'ch and the prClJX)rtloning potentiometer are functioning at the same Ifme. When Ihe pressure falls to the sel point minus the differential, Ihe on-oN switch makes and the burner Is lumacl on. The potentiometer wiper is aU the way over to the Bend, lhe firing rate Controls are a! the high fire jXlSi- tion. and the bUrner starts al high fire, As the burner heats l4=l and the pressure increases, the wiper moves toward the W end of the potentiometer. It the pressure contlnues 10 Increase, the Wiper moves all the way to the Wend and !he firing rate conlrols are at the low tire ~ilion. Ordinar- Ily, modulallon keeps the pressure belW9Eln thess posi- lions within lhe proportioning range. If It prOblem devek:ps or the Iced drops suddenly, and the pressure continues 10 rise, the on~f'I' switch breaks and shuts down lhe bUrner when the pressure reaches lhe main scale sel point. In the SEQUENCE posilion, Ihe prqx>rtionlng range is entirely below Ihe differenlial range, so the on~ff switch and the proportioning potentiomeler are not funclioning al 224 the same time. As in the UNISON position, when the pressure falls 10 lhe sel point minus Ihe differential, Ihe on-off switch makes and the burner is turned on. However, the potentiometer wiper is all the way over to the Wend, the 1iring rale controls are al the low tire position, and the burner starts at low fire, It the pressure continues to fall be- 10re the burner can heat up, the Wiper moves toward the B end at the poten/iometer. If the pressure 1alls far enough, Ihe wiper moves all the way 10 the B end and the firing rate controls at the l1igh fire posilion. As the burner heats l.4) and the pressure increases, the Wiper moves toward the Wend at the potentiomete(. Again, the pressure is ordinar- ily kept within the proportioning range. t1the pressure con- linues to rise, the wiper moves all the way 10 theW end and lhe 1iring rale contrOlS are at the low tire jXlSilian. The burner slays at low 1ire as the pressure increases through the differential range, and is Shut do ·:n when Ihe pressure react'19S the main scale sel point. In an intermecliale jXlSition, the proportioning potentiometer is functioning partly wllhin the differential range of the an~N switch-the amount varies with the ~ilion. This provides a ChOice of lhe firing rale-somewhere between low 1ire and high fire-al burner startl4=l when the on~ff switch makes. As shown In Fig. 13, the pressure range over which the burner will operate at low fjre also varies with the position 011he UNISON/SEQUENCE dial. • ( -"'GH • ,,~t , ,. I "'I.UNG ""ESSURE " ", j U"'SON / OI'ERATlO,", r-_~/ \ \, \ I ~ \ / ~ \ I ( /,," \"'li' 'oJ _ l~" I -"'G a "M I I -H'OH • FIRE I I I I I • ',AE I r iL" I I I I I I I I 'HTrRWW'''rf OHRATlO'l \ -, I I rli l 1'-_ / -, \ ,\J I \ //\, \_~ I I I", 1\.\1 r- , \"""(\1 I I 1 - \ I I I 1'':-:, r\il J I \"5\ '''' . ./ I \-\ '''' I I 1 <; ,,_ I L ____ J L __ :'_J L ____ J \ ",.,loC>NlllOJ<JVICE AOJusr nn I I I U(]UENn O"ERA"<lN , \ I l@) .I FIG. 13-0PERATION OF THE P455 COMBINATION PROPORTIONING AND ON-OFF PRESSURE CONTROLLER. PRESSURE CONTROLLERS (PRESSURE SWITCHES) USED IN GAS BURNER SYSTEMS The pressure controllers used in gas burner systems are commonly called gas pressure swilchas_ They may be used with natural gas, LP gas, or air. (The C64sC and D models can be used only with air.} They provide safety shutoff or diflerential-pressure control, depending on the controllsr model and wiring hookup (Figs. 3-5). No proportioning controllers are available tor use in gas burner systems. LOCATION AND MOUNTING Gas pressure switches in the main burner line should be located downstream from the PRII (pressure rBgJlaling valve). The low gas pressure switch should be localed u(r stream from the safety shutoff valve(s). In a downstream location, there would be zero preSsure when lhe burner Isn'( running and the safely shutoff valve(s) is closed. This could prevent startup or reqUire manual reset every time the burner is started. The high gas pressure switch should 225 be located as near thE! burner as p:;lSSibre. Typical loCa- tions arE! shown In Fig. 14. A pressure switch is t JSllally rrounted dlrectPy on the main pipe by Inserling a tBEI in the pipe lJne, and connecting a pipe nil=flle at appropriate size 10 the tBEI (Fig. 15). Screw the main pressure connection ot Ihe pressure switch to the pipe nil=flle. The main connection is a heJt- agonallilling with 1/4 or 1/2 inch NPT Internal threadS. To avoid leaks and damage to the case. use a parallel jaw wrench on the hexag::mal fitling close 10 lhe pipe ni~le. Make all connections carefully and lest lor leakage. Do not tighten rhe pressure swifch by hand by holding the case. In some cases, it may be more convenient (0 mountlha pressure switch on a nearby wall. using the optia'lal mounting bracket. The braCket should be Installed before connecting the piping from the main line. ContrOllers with mercury swilches (C437. C447, C637, (;647) must be carefully leveled as described In Basic Pri". 71-97558-1 FIRING RATE SSOV CONTROL o MSOV MAIPIl VENT 'RV MSOV i=t~~;E}::;~BUlrER HIGH GASPS BURNER PRESSURE • PILOT LINE TEST TAP MSOY _ MANUAL SHUTOFF VALVE PRY - PRESSURE REGULATING VALVE PS - PRESSURE SWITCH SSOY - SAFETY SHUTOFF VALVE FIG. 14-TVPICAL LOCATIONS OF THE GAS PRESSURE SWITCHES IN THE MAIN BURNER LINE. ciples of Controllers. C645 Pressure Swilches are snap- a. Hazardous (combustible) gas-Install a vent pipe at acting, so they 00 nol have 10 be leveled, The C645A,B, or the venl conneclion so that any gas leakage will be o may be mounted in any position, but they are slighlly vented into the combustion Chamber or to another more accurale when mounled with the diaphragm hOri· safe place in case the diaphragm in the pressure zontal. The C645C (low operating pressure range) must switch fails, be mounted with the diaphragm vertical and (he vent con- b. DifferentjaJ pressure-Connect the high pressure nection (bleed fitllngl at the I:ollom. side at the system to the main pressure connection, A vent connection (1/B inch NPT with inlernal lhreaci5) and the low side to the venl conneclion. This appli- is provided on all pressure switches. This connection must Cation cannot be used with hazaroous gases as no be used in the following awlications: venting is possible. c. Negative prflSSUre - Connect the low pressure side __ ~AS ~~tsSV~E: SWITCH IAT RIGHT .~GLE:S TO THE: M.'~ ~I'E: L'~E) Ii MAI~ ~IPE L1NE ",'EHE [TIJR~ TO LEVEL T"E ~RESSURE SWITCHl FIG. 15- MOUNTING A GAS PRESSURE SWITCH DIRECTLY ON THE MAIN PIPE. to the vent connection. This awlication also cannot be used with hazarcbus gases, When using a pressure switch with a low pressure range, momentary pressure surges or &bumps" can cause the switch to break. Orifices are available for C437 and C637 Pressure Switches to eliminate or reduce chal· lering or nuisance lockouts caused by Ihese -bumps.· An orifice is inserted in the main pressure connection (Fig. 16) [0 reduce the effect at pressure surges. The bushing and ORI FICE TOOl AG. 16-INSTALLING AN ORIFICE IN A C437 OR C637. 226 onfice 1001 shown are used only for installation at the ori- tice, and are removed afterward. PRESSURE SWITCH SETIING Industrial Risk Insurers (formerly F.LA.) recommenc1s that gas pressure switches on the manifold be seln accordance with the turncklwn range of Ihe installation. They recommend thatlhe high gas pressure switch be sal 20 per,cent above Ihe maXimum firino rate pressure, and the low gas pressure switch be set 20 10 50 percent below the minimum firing' rate pressure, wilh the preference being 20 percent. ,,' J.IMllli, C0l'ltrp1lehf ", 'andlntlllrlocks HONEYWELL PRESSURE CONTROLLERS AVAILABLE FOR USE IN GAS BURNER SYSTEMS HoneyweJl pressure conlrollers evailable are listed ;n Table II al the end of Ihis section, along with their awlications, switch types, and operating pressure ranges. Fig. 17 shows the models listed, All models operale as d&- scribed in Basic Principles 01 Controllers. For runher infor- mation, reler to the instruction sheats for the controllers. PRESSURE CONTROLLERS USED IN OIL BURNER SySTEMS Prassure controllers are used in oil burner systems to supervise oil pressure and to supervise the pressure 01 the atomizing medium (if used). OIL PRESSURE SUPERVISION The Oil pressure controllers (also called oil pressure SWitches) discussed in this section can be used with any type of fuel oil, inclUding heavy preheated oils. They have a stainless steel diaphragm to resisl corrosion. The dia· phragm transmits changes in oil pressure to an spst mercury switch Ihrough a mechanical linkage. The L404T and Ware high pressure limits; they break a circuit and st'1ut down the system if the oil pressure gets too high. The L404V and Yare operating controllers and low pressure limits: they preventlhe system from staning untillhe oil pressure is high enough, and they Shut down Ihe system ir lhe oil pressure falls too low. TIle L404T and V have adjustable subtractive differenhals: the L404W and Yare manual reset models. C447.C547 _ LOCATION AND MOUNTING Oil pressure controllers can be mounledat any location in Ihe ojl supply line, dePending on Ihe application. Typical loca/lons are shown in Fig. 18. The low oil pressure switch should be located upsrrfjam from 1M safely shutoff valve{S), In a downstream location, there would be zero pressure when the burner isn't running and the safety Shu10ff valve(s) is closed. This could prevent startup or require manual reset every time the burner is staned. The hiGh oil pressure switCh should be located as near the burner as possible. An oil pressure controller is mounted directly on the main pipe by inserting a tee in tha pipe line. and cOnnect- ing a pipe ,iJ:Ple of appropriate size to lhe tea (FiQ. 19). Screw Ihe he:tagonal fitting (1/4 inch NPT with internal threads) at the pressure controller to lhe pipe niJ:Ple. To avoid leaks and damage to Ihe case, use a paralle! jaw wrench on the hexagonal filling close to the pipe niJ:Ple. Do not tighten rhe pressure contro/ler by hand by holding the caSe. FIG. 17-HONEYWEU PRESSURE SWITCHES AVAILABLE FOR USE IN GAS BURNER SYSTEMS. 227 71·97558-1 MAIN mL UNE • TO OIL )=~~=~==p':I:;!==~=:::t';j.E:J==-::=CJ-=t~:E~BU;NER FIRING SSOV ANO RATE RECIRCULATING CONTROL VALVE LOW A.M.PS ATOMIZING MEDIUM. ====:":===::=J (AIR OR STEAMI " MSOV - MANUAL SHUTOFF VALVE - PRESSURE SWITCH ssov - SAFETY SHUTOFF VALVE A,M, PS - ATOMI21NG MEOIUM PRESSURE SWITCH FIG. 1B-TYPICAL LOCATIONS QFPRESSURE CONTROLLERS (SWITCHES) IN AN OIL BURNER SYSTEM. Make all pipe conneclions in accordance wilh ap- proved 5tandardi. Use only a small amount of pipe com- pourd 10 seal the connection joints. Excess pipe Corrp:lUnd may Clog Ihe small hole in the filling and prevent the controller from operating prcperly. When used with preheated oil, a siphon 10ClP must always be connecteCl between the controller and the main pipe {Fig. 20) to provide thermal buffering. The 10ClP must always be perpendicular to the face of the controller. If the 10ClP is parallel 10 the controller, expansion or contraction of the 10ClP will tip the controller and cause the switch to cperate lnaceuralely. Oil pressure controllers have· mercury switches, so they must be leveled for proper operation. If mounting directly on the main pipe (Fig. 19), install the controller at rIght angles to the pipe; leveling can then be accom- plished by turning the pipe 100. If using a siphon 10ClP with prehealed oil (Ag. 20), leveling can be accorTfJIlshed b)I carefully bending the siphon 10ClP. The controller is level when the leveling indicator hangs freely with lis pointer directly over the Index mark on the back of the case (see Rg.2). WIRING HOOKUPS If the oil burner system is a single burner system with an integral oil pump, connectlhe oil pressure controller In series between the flame safeguard control and the main oil valve solenoid (Fig. 21). If it is a single burner or a multibur- ner system with an external oil pump, connect the oil pres- 228 sure conlroller in series wilh the other controllers, limits ard interlocks (Fig. 22). SUPERVISION OF ATOMIZING MEDIUM PRESSURE (AIR OR STEAM) When air or steam is used as an atomi.ing medium, aulhorities having jurisdictiqn (approval bodies and codes) often require a-rowiimitto prevent openinQ of the main oil valve unlil sufficient atomizing pressure is pre- senl, and to shut Gbwn the system if the atomi2inQ pres- sura falls too low. The L404B Pressure Controller, designed tor use on steam boilers and hot water healing systems, is recommended tor (his appllcallt:rl. It has an spst mercury switch wilh an adjuslable Slblraclive diMerenlial. The switch makes a circuit when the pressure rises to the set jX)int, and breaks when the pressore fcllls to the set point minus the differential (see Fig. 8). The L404B is available in 4 0p- erating pressure ranges, from 2 to 300 psi. LOCATION AND MOUNTING The L404B is mounled in Ihe supply line for the atomizing medium (Fig. 18). Follow the same mounting instruc- lions as for the ofl pressure c?1trollers. WIRING HOOKUPS The cperation of the L404B Is the same as for the L4D4V,Y (makeS on pressure rise to setjX)int). II should be connected In series with lhe oil pressure controller (Fig. 21 or 22). , /Oll PJtU,5UR£ ~ONTFlQLlE~ ., (Ar "'G"r ANGLES TO THE "' ".E UNE) .'.fTEE (lU"" TO U\I[L THE CONrJtOLUlOI L "" FIG. 19- MOUNTING AN OIL PRESSURE CONTROLLER DIRECTLY ON THE MAIN PIPE. , ; 4 2 T051 1114 TO 1401 L 14026 SIPHO"& LOOP • Oil PIlUSWI[ CONHIOllER • PflEI'iE",Tl:O OIL PREl'itATED O'L SUP'PLV LINt SU","L.II 1,.10'[ & (, eli eLACI( IRON "P[ WITH 1/""'"PT [)(TEIlN 1 THREAOS Oil BOTH ENDS. 8tHD TIiE SIPHON LOOP TO LEVEL THECONTIIOLL.ER. I "F'" GC" =2-=O-_-C R :cC"O:cC"WC"R"O"NC"G= =M"O"U- N ='::N"G-O"F"A" "'-=GC"H::T" AH -C T SIPHON LOOP, WITH APPROXIMATE DIMENSIONS IN INCHES [MILLIMETRES IN BRACKETS). HONEYWELL PRESSURE CONTROLLERS AVAILABLE FOR USE IN Oil BURNER SYSTEMS Honeywell pressure controllers allailable are lislad In Tabla II al (he end or this section, along with their awica· !.ions, switch types, and operating pressure ranges. Fig. 23 shows the models listed. For further infonna(ion, refer to the instruction sheets lor lhe con/rollers. OllPAE$SIJAE , .,"vALvE '~""l UoHGUAIIIO CONTIIIO~ U ~ - FIG. 21 - HOOKUP OF AN OIL PRESSURE CONTROLLER USED ON A SINGLE BURNER SYSTEM WITH AN INTEGRAL OIL PUMP. FIG. 22- HOOKUP OF AN Oil PRESSURE CONTROLLER USED ON A SINGLE BURNER OR MUL TIBURNER SYSTEM WITH AN EXTERNAL OIL PUMP. L.O&Oo&T,V,W,Y L __ ('_·_'_·B_"_'_'._'_'_A_._' ~ FIG. 23- HONEYWELL PRESSURE CONTROLLERS AVAILABLE FOR USE IN OIL BURNER SYSTEMS. SETTING PRESSURE CONTROLLERS The operating p:>ints 01 pressure controllers are set by tq::l of the case. as shown in Figs. 24 and 25. Sealeplales turning ild}usting screws or knobs, usually located on the are rnar1<oo in in. we (inches of vwater colLKm), in psi 229 71-97556-1 I [...]... '00 'SO JOO kg/em 2 ,p, 7. 47 12.45 24.91 1 27 105~6 14062 24608 35154 70 309 105463 2109 27 SCAlE PROPORTIONrNG R"'N(;E ADJUSTING seRE'" AOJUST'NO 31 68.95 0,249 0 ,74 7 , 245 2.491 S.231 6,895 0.00254 0,0 076 2 0,01 27 0.0254 0.0533 0. 070 3 7 , 1406 3516 70 3' M"r" SCREW 49 254 533 10 8304 mllll brr b 25.4 75 .2 0108 0,181 0.361 0 .75 276 8 4152 _ mm 0' WATER a 1 37, 34 47 689.5 1C.34 1 379 2t13 3m 689' 10342 ""54... 248 -301O +70 F 30 10 270 F [-34 10 + 21 Cj [-1 10 + 130 CJ CJ -30to +70 F [-34 10 + 21 C] 160 to 260 F [75 10 125 C] 010100F +38C] 160 10 260 F [71 to 1 27 C] r~1e1O 1 70 10 140 F [2110 60 C) - 1 70 10 140 F [2110 60 CJ - 1 potentiometer T991B T991F 11010290 F 10 143 C) 1. . 7. 47 0,0 076 2 0 ,74 7 0108 75 .2 , , .245 10 12.45 0,01 27 0,181 1 27 24.91 0.0254 2.491 0.0533 0.361 254 S.231 0 .75 533 .31 2' 68.95 0. 070 3 6,895 1.000 70 3 , 7 , -R~ 7 0 .70 31 276 8. the main line. ContrOllers with mercury swilches (C4 37. C4 47, C6 37, (;6 47) must be carefully leveled as described In Basic Pri". 71 - 975 58-1 FIRING RATE SSOV CONTROL o MSOV MAIPIl. detailed explanation of this operation, refer to the Flame Safeguard Reference on Firing Rale Controls, 10rm 70 -81 17. ) As the controliEld variable rises, the Wiper will move toward

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