Types 92B and 92P D100703X012 Instruction Manual Form 1329 0ctober 2002 www.FISHERregulators.com Introduction Scope of Manual This manual provides instructions for installation, startup, maintenance, and a parts list for the Types 92B and 92P valves. Instructions and parts lists for other equipment used with these valves are found in separate manuals. The Type 92B is also available with a Type 6492HM or 6492HTM safety override pilot. Product Description The Type 92B Pressure Reducing Valve (PRV) is the standard steam valve for industry. It can withstand dirty operating environments while providing accurate and stable pressure control. The Type 92B is applied as a main pressure reducing valve in industrial process heating applications such as heat exchangers, evapora- tors, digesters, and reactors. Commercial applications include PRVs for meter runs found in district energy systems, hot water heat exchangers, absorption chillers, and boiler deaerator tanks. The air loaded, pilotless version of the Type 92B is the Type 92P. The Type 92P is an air-loaded, pressure reducing valve which is pressure balanced. The Type 92P is air loaded using a Type 67CFR airset, a Type 670 panel loader, or a PID Controller. A Type 6492HM safety override pilot is available for the Type 92B. The Type 92B pilot is used in a series installation with the Type 6492HM safety override pilot installed on the upstream valve. The Type 6492HM safety override pilot senses pressure downstream of the second valve, and prevents pressure from rising above safe operating pressure in the event the down- stream valve fails. This system is approved by ASME B31.1-1989, 122.14.2.A, and can replace an ASME safety valve when vent piping is not practical and upstream steam pressure does not exceed 400 psig (27,6 bar). Local codes and standards may require approval by an appropriate authority prior to installation. Type 92B Pressure Reducing Valve (PRV) and Type 92P Air-Loaded Pressure Reducing Valve The Type 92B safety override system does not provide positive shutoff in dead end service. It is intended for large distribu- tion systems where steam leakage will condense before steam pressure builds- up. Downstream piping and components must be rated for maximum upstream steam pressure for dead end service. Failure to do so could cause personal injury or death. Specifications Specifications are given for the Types 92B and 92P valves on page 2. Specifications for a given valve as it originally comes from the factory are stamped on the nameplate. Figure 1. Type 92B Pressure Reducing Valve W8264
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Transcript
Types 92B and 92P
D100
703X
012
Instruction ManualForm 1329
0ctober 2002
www.FISHERregulators.com
IntroductionScope of ManualThis manual provides instructions for installation,startup, maintenance, and a parts list for the Types 92Band 92P valves. Instructions and parts lists for otherequipment used with these valves are found in separatemanuals. The Type 92B is also available with a Type6492HM or 6492HTM safety override pilot.
Product DescriptionThe Type 92B Pressure Reducing Valve (PRV) is thestandard steam valve for industry. It can withstand dirtyoperating environments while providing accurate andstable pressure control. The Type 92B is applied as amain pressure reducing valve in industrial processheating applications such as heat exchangers, evapora-tors, digesters, and reactors. Commercial applicationsinclude PRVs for meter runs found in district energysystems, hot water heat exchangers, absorption chillers,and boiler deaerator tanks.
The air loaded, pilotless version of the Type 92B is theType 92P. The Type 92P is an air-loaded, pressurereducing valve which is pressure balanced. TheType 92P is air loaded using a Type 67CFR airset, aType 670 panel loader, or a PID Controller.
A Type 6492HM safety override pilot is available for theType 92B. The Type 92B pilot is used in a seriesinstallation with the Type 6492HM safety override pilotinstalled on the upstream valve. The Type 6492HMsafety override pilot senses pressure downstream ofthe second valve, and prevents pressure from risingabove safe operating pressure in the event the down-stream valve fails. This system is approved by ASMEB31.1-1989, 122.14.2.A, and can replace an ASMEsafety valve when vent piping is not practical andupstream steam pressure does not exceed 400 psig(27,6 bar). Local codes and standards may requireapproval by an appropriate authority prior to installation.
The Type 92B safety override system doesnot provide positive shutoff in dead endservice. It is intended for large distribu-tion systems where steam leakage willcondense before steam pressure builds-up. Downstream piping and componentsmust be rated for maximum upstreamsteam pressure for dead end service.Failure to do so could cause personalinjury or death.
SpecificationsSpecifications are given for the Types 92B and 92Pvalves on page 2. Specifications for a given valve as itoriginally comes from the factory are stamped on thenameplate.
Figure 1. Type 92B Pressure Reducing Valve
W8264
Types 92B and 92P
2
Available ConfigurationsType 92B: Pilot-operated globe-style pressurereducing valve with post guiding and flow to closevalve plug actionType 92P: Pilotless version of the Type 92B forremote pressure loading
Body Sizes and End Connection StylesSee table 1
Body Ratings and Maximum Inlet Pressures(1)
See table 3Maximum Outlet (Casing) Pressure
Cast Iron: 150 psig (10,3 bar) or body rating limits,whichever is lowerSteel/Stainless steel: 300 psig (21 bar) or bodyrating limits, whichever is lower
Outlet Pressure Ranges(1)
See table 2
1. The pressure/temperature limits in this instruction manual or any applicable standard limitation should not be exceeded.2. Trademark of International Nickel Co.
SpecificationsMinimum Differential Pressure Required for FullStroke(1)
Type 92B: 20 psig (1,4 bar) with stainless steelspring; 10 psig (0,69 bar) with Inconel(2) springType 92P: 5 psig (0,34 bar)
Type 92P Maximum Diaphragm Loading Pressure150 psig (10,3 bar)
Pressure RegistrationExternal
Maximum Temperature Capabilities(1)
See table 3
Downstream Control Line Connections1 and 1-1/2-inch bodies: 1/4-inch NPT2-inch body: 3/8-inch NPT3 and 4-inch bodies: 1/2-inch NPT
Principle Of OperationType 92BRefer to the operational schematic in figure 2. Com-pression of the pilot spring (A) pushes the diaphragm(B) down and holds the pilot valve plug (C) open. Outletpressure is changed by varying the amount of pilotspring compression.
When steam enters the inlet of the valve, it also entersthe pilot supply line (F) and flows through the open pilotvalve to the top of the main diaphragm (H). The forcecreated by this steam pressure on the diaphragmovercomes the force of the main valve spring (E)opening the valve plug (D) and allowing steam to flowdownstream. Downstream pressure registers under themain diaphragm through the control line (J) and tends tobalance the diaphragm. Steam from the downstreamsystem also registers under the pilot diaphragm throughline (L). Pressure forces the diaphragm (B) upward,permitting the pilot valve plug to move toward the closedposition. Flow of steam to the top of the main diaphragmis thereby reduced and the pressure on main diaphragmdrops due to the bleed through the orifice (N). The mainvalve moves toward the closed position, allowing onlyenough steam flow to satisfy downstream requirements.
When steam demand increases, the downstreampressure decreases below the setting of the pilot spring.The pilot opens to increase the pressure on the main
diaphragm. The main valve opens to increase the flowdownstream. Conversely, if the steam demand de-creases, the downstream pressure increases and thepilot reacts to decrease the pressure on top of the maindiaphragm. The main valve throttles toward the closedposition and the steam flow decreases. Thus, throughthe combination of pilot and main valve operation, controlof the downstream steam pressure is maintained.
A check valve is included in all Type 92B pilots to limitdifferential pressure on the main valve diaphragm. Inthe event of a large decrease in downstream pressure,the check valve opens to relieve diaphragm loadingpressure to the downstream system. The check valvecartridge assembly has a factory setting to limitdifferential pressure across the diaphragm to approxi-mately 40 psid (2,8 bar d). If diaphragm differentialpressure exceeds 40 psid (2,8 bar d), the check valveopens to relieve diaphragm loading pressure into thedownstream system, thereby preventing a high differen-tial across the diaphragm which might otherwise causediaphragm damage. The check valve closes andnormal operation resumes when the differential pressureacross the diaphragm is reduced to the proper level.
Type 92PRefer to the schematic illustration in figure 3. Whenoperation begins, a constant pressure is loaded ondiaphragm (H). The diaphragm force opposes spring (E)
and tends to open valve (D), allowing steam to flowdownstream. The downstream pressure registers underthe main diaphragm through control line (J) and tends tobalance the diaphragm force. As the downstreampressure builds up, the pressure on the bottom side ofthe diaphragm approaches the pressure on the top,tending to close the valve.
When steam demand increases, the downstreampressure decreases. The pressure on the bottom sideof the main diaphragm decreases, allowing the valve toopen farther. If the steam demand decreases, thedownstream pressure increases and pressure increaseson the bottom of the main diaphragm, overcoming thebalance and causing the valve to move toward theclosed position.
Type 6492HM Safety Override SystemRefer to the Schematic illustration in figure 4. Onceplaced in operation, the upstream Type 92B (B) pilotsenses the intermediate pressure between bothvalves, and the Type 6492HM (A) pilot senses down-stream pressure of the second valve. As demand forflow increases, intermediate pressure will fall causingthe Type 92B pilot to open. As the Type 92B pilotopens, loading pressure to the main valve increases,opening the main valve.
The Type 6492HM (A) safety override pilot remains openbecause its setpoint is above the setpoint of the down-stream valve. In the unlikely event that the downstreamvalve fails open, downstream pressure will rise above thedownstream valve�s setpoint. This pressure is sensed bythe Type 6492HM (A) safety override pilot. As down-stream pressure increases the Type 6492HM (A) safety
override pilot closes, reducing loading pressure to theupstream main valve, which positions the main valve tomaintain desired downstream override pressure.
In the event that the upstream valve fails, the down-stream valve will prevent downstream pressure fromrising above safe operating levels.
It is recommended to install some type of warningsystem, such as a sentinal relief valve, to warn theoperator that a valve has failed in the system. This willprevent prolonged operation with one valve, which couldcause valve trim wear and noise associated withoperation at high differential pressures.
Installation
Type 92B
Regulators should be installed, operatedand maintained in accordance with federal,state and local codes, rules and regula-tions, and Fisher instructions. If the regula-tor vents steam or a leak develops in thesystem, it indicates that service is required.
Failure to take the regulator out of serviceimmediately may create a hazardouscondition.
Call a serviceman in case of trouble. Onlya qualified person must install or servicethe regulator.
Figure 3. Type 92P Operational Schematic Use a Fisher Type 670 manual loading station or other suitable air regulator to control loading pressure to the Type 92P.
Be sure to install Type 92B pilot abovethe pipeline with the adjusting screwpointing up and the control line slopedat a downward pitch to the main line toensure proper condensate drainage.
The following points should be kept in mind wheninstalling this pressure reducing valve. See figure 5 fora schematic drawing of a typical installation.
1. Inspect the Type 92B for any shipment damage.Remove any foreign materials that may have collectedin the valve during shipment.
2. Blow down the pipeline as required.
3. Install a strainer ahead of the Type 92B to protectthe internal parts of the valve.
4. Install an upstream block valve ahead of theType 92B and a downstream block valve, if required, sothat the valve can be isolated and serviced. If continu-ous operation is necessary during maintenance orinspection, install bypass piping and valve around theType 92B.
5. This Type 92B is intended to be installed with thediaphragm case above the pipeline so that condensatewill not collect in the case.
TYPE 6492HM SAFETYOVERRIDE PILOT (A)
TYPE 92B PILOT (B) TYPE 92B PILOT (C)
TYPE 92B MAIN VALVE TYPE 92B MAIN VALVE
Table 4. Minimum Differential Pressures for Safety Override System
6. Install the Type 92B in the pipeline so that the flowwill be in the direction indicated by the arrow cast onthe body. Follow normal piping procedures wheninstalling the screwed or flanged control valve.
7. Install the external control line as follows:
a) Connect one end of the control line to theType 92B body tapping. This NPT tapping is 1/4-inchfor 1 and 1-1/2-inch bodies, 3/8-inch for 2-inch body,and 1/2-inch for 3 and 4-inch bodies.
Note
The control line should be as large as thetapped hole in the Type 92B.
b) The other end of the control line is connected tothe downstream system. Place the tapped hole for thisconnection in a straight run of pipe 3 to 5 feet from thecontrol valve when the valve body is the same size asthe pipeline. If the valve body is smaller than thepipeline and requires swage nipples, place the tappedhole at a distance from the swage connection equal to10 times the pipe diameter.
c) Do not locate the control line tap in an elbow,swage, or other changes in configuration of the pipelinewhere turbulence or abnormal velocities may occur.
d) Do not locate the control line tap in a vessel(such as a deaerator) located immediately downstreamof the control valve. Locate the tap in the pipelineleading to the vessel.
e) Slope the control line away from the Type 92B sothat condensate can drain back into the pipeline.
f) Install a shutoff valve (not a needle valve) in thecontrol line.
g) Install a pressure gauge in the control line ornear the outlet of the Type 92B to aid in setting theoutlet pressure.
The maximum inlet and outlet pressuresfor which this Type 92B has been manu-factured should not be exceeded. Thesepressures are stamped on the nameplatesattached to the main valve and pilot.
Types 92B and 92P
8
Type 92PLoading Relay � Any suitable air loading regulatorsuch as a Fisher Type 67, 670 or 1301F Series can beused as a loading relay. It is recommended that ableed orifice be installed in the second outlet of theloading relay.
1. Inspect the Type 92P for any shipment damage.Remove any foreign matter that may have collected inthe valve during shipment.
2. Blow down the pipe line wherever practical.
3. Install a strainer ahead of the valve to protect theinternal parts of the valve.
4. Install an upstream block valve ahead of theType 92P so that the regulator can be isolated andserviced. If continuous operation is necessary duringmaintenance or inspection, install a bypass valve andpiping around the Type 92P and a block valve in thedownstream.
5. This Type 92P is intended to be installed with thediaphragm case above the pipeline so that condensatewill not collect in the case.
6. Install the Type 92P in the pipeline so that the flowwill be in the direction indicated by the arrow cast on
the body. Follow normal piping procedures wheninstalling the screwed or flanged Type 92P.
7. Install the external control lines as follows:
a) Connect one end of the control line to theType 92P body tapping. This NPT tapping is 1/4-inchfor 1 and 1-1/2-inch bodies, 3/8-inch a for2-inch body, or 1/2-inch for 3 and 4-inch bodies.
Note
The control line should be as large as thetapped hole in the Type 92P.
b) The other end of the control line is connected tothe downstream system. Place the tapped hole for thisconnection in a straight run of pipe 3 to 5 feet from thecontrol valve when the valve body is the same size asthe pipeline. If the valve body is smaller than thepipeline and requires swage nipples, place the tappedhole at a distance from the swage connection equal to10 times the pipe diameter.
c) Do not locate the control line tap in an elbow,swage or other section of the pipeline where turbulenceor abnormal velocity may occur.
d) Do not locate the control line tap in a vessel(such as a deaerator) located immediately downstream
Figure 7. Pneumatically Operated Heat Exchanger Installation With Temperature ControlThe Fisher Type 92P air-loaded control valve receives air-loading pressure from a Type 4196 Wizard Controller and Amplifying Relay.This positions the Type 92P to maintain steam flow necessary to control outlet temperature of the heat exchanger. Packing friction is
eliminated improving response time. Packing leaks are eliminated reducing maintenance.
BLEED FITTING
TYPE 92P
TRAP
TYPE 4196 CONTROLLER
TYPE 67CFR
HEAT EXCHANGER
WELL
100 PSIG(6,9 bar)AIRAMPLIFYING RELAY
100 PSIG (6,9 bar)AIR
3 - 15 PSIG(0,21 - 1,0 bar)
HOT WATER
COLD WATER
Types 92B and 92P
9
of the Type 92B. Locate the tap in the pipeline leadingto the vessel.
e) Slope the control line away from the Type 92Pso that condensate can drain back into the pipeline.
f) Install a shutoff valve (not a needle valve) in thecontrol line.
g) Install a pressure gauge in the control line ornear the outlet of the control valve to aid in setting themanual loader.
The maximum inlet and outlet pressuresfor which this Type 92P has been manu-factured should not be exceeded. Thesepressures are stamped on the nameplateattached to the control valve.
Startup and Adjustment
Failure to remove accumulated conden-sate may result in severe condensationinduced water hammer which can resultin personal injury or death.
Prior to valve startup:New InstallationsBlow down inlet steam piping to remove any debrissuch as weld beads by opening the drain valve of theinlet stainer to the control valve. Close the isolationvalve and disassemble strainer to remove accumulatedebris. Repeat as necessary until strainer basket isfree of debris.
Old InstallationsOpen all upstream and downstream drain valves at driplegs and strainers to drain condensate that may haveaccumulated during the shutdown period. Crack theinlet isolation valve to the pressure reducing stations toflush any residual condensate. Close the drain valvesonce the drain is free of condensate.
Pilot AdjustmentTo adjust the downstream reduced pressure setting,turn the set screw clockwise into the spring case to
increase the downstream pressure setting. Turn itcounterclockwise out of the spring case to decreasethe setting. Loosen hex nut on screw before adjust-ment and tighten it once adjustment is made.
Type 92BTo put the valve into operation after installation or afterdisassembly for inspection or repairs, proceed asfollows, referring to figures 5, 11, and 12 as necessary.
1. Relieve all spring compression on the pilot springby loosening hex nut (key 16) and turning set screw(key 15) counterclockwise (out of the spring case).
2. Open the upstream block valve.
3. Open the downstream block valve slowly.
4. Close the bypass valve.
5. Slowly turn the set screw of the pilot clockwise intothe spring case until the downstream pressure reachesthe required setting. Tighten hex nut on the set screw.
Type 92PUse the following procedure to put the valve intooperation:
1. Open the upstream block valve.
2. Slowly open the downstream block valve.
3. Close the bypass valve.
4. Adjust the control system to obtain the desiredcontrolled pressure.
The only adjustment that will affect the 92P is thepressure setting of the control system.
Safety Override SystemUse the following procedure to put the system intooperation, referring to figure 4 as necessary:
1. Remove all pilot control spring compression from theType 6492HM safety override pilot (A) by turning theadjusting screw out of the spring case (counterclockwise).
2. Adjust the Type 92B upstream working pilot�s (B)and Type 92B downstream working pilot�s (C) adjustingscrews into the spring case (clockwise) to their maxi-mum adjustment.
3. SLOWLY open the upstream block valve to intro-duce inlet pressure to the system.
Types 92B and 92P
10
4. Open the downstream block valve and control lineblock valves, if used.
Note
Some flow is needed to make pressuresettings accurate.
5. If a bypass is used, slowly close the bypass lineblock valve.
6. Adjust the Type 6492HM safety override pilot (A) tothe desired downstream override pressure. The safetyoverride pilot�s setpoint must be higher than the down-stream working pilot�s (C) setpoint by the amountslisted in table 4.
Note
The normal pressure and maximumoverride pressure should be set at orbelow the safe working pressure of theequipment and piping system down-stream. (Reference applicable codes and/or standards for maximum allowable orsafe working pressures for equipmentand piping systems served.)
7. Adjust the Type 92B downstream working pilot (C)to the desired normal downstream control pressure.
8. Adjust the Type 92B upstream working pilot (B) tothe desired intermediate control pressure (typically 50%of inlet pressure).
9. Readjust the Type 92B downstream working pilot(C) to the desired normal downstream control pressure,if necessary.
10. Tighten the lock nuts on all pilots to lock theadjusting screws in position.
TroubleshootingOperating difficulties may be experienced with thisvalve as a result of improper installation, impropervalve sizing, damage to internal parts, trim wear, or anaccumulation of dirt, boiler compound, or other foreignmaterials on internal parts. When trouble occurs, checkthe following:
Type 92BBuildup of Downstream Pressure1. Check for plugged bleed fitting (key 61, figure 10).
2. Check the screen (key 77, figure 11 or 12) forclogging and the other pilot internal parts for accumula-tion of dirt, boiler compound, or other materials.
Failure to Maintain Downstream Pressure1. Check for ruptured diaphragm (key 60, figure 10).2. Check to see that the valve is not undersized.
Cycling or HuntingCheck to see that the valve is not oversized. A cyclingType 92B might possibly control the downstreampressure within acceptable limits but the life of thediaphragms, guide bushings, seat ring, and valve plugcould be greatly reduced.
If cycling occurs, as a result of oversizing or othercauses, it can frequently be minimized by reducing thegain of the Type 92B. This can be accomplished byinstalling a suitable reducing regulator such as a Type95H in the Type 92B pilot supply line (�F� of figure 2).Adjust the pilot supply line regulator to reduce pilotsupply pressure to about 30 psig (2,1 bar) above theoutlet pressure setting of the Type 92B valve. Thisarrangement can minimize cycling and still provideadequate pilot supply pressure to ensure full opening ofthe main valve plug, if required.
Note
The 30 psig (2,1 bar) is suggested for unitswhich include the standard 17-4 PHstainless steel main spring. This springrequires approximately 20 psig (1,4 bar)diaphragm differential pressure to fullystroke the main valve. If the lighter rateInconel spring is used, only about 10 psig(0,69 bar) diaphragm differential pressureis required to fully stroke the unit. There-fore, the pilot supply pressure can bereduced to about 20 psig (1,4 bar) abovethe outlet pressure setting of the controlvalve without loss of control capability.
Type 92P
Buildup of Downstream Pressure withoutLoading Pressure on the Diaphragm1. Check internal parts for buildup of dirt, boiler
compound, or other matter.
2. Check the trim for seizing or galling.
Types 92B and 92P
11
Failure to Maintain Downstream Pressure1. Check for ruptured diaphragm (key 10, figure 17).2. Check to see that the valve is not undersized.
Cycling or HuntingCheck to see that the valve is not oversized. A cyclingType 92P might possibly control the downstreampressure within acceptable limits but the life of thediaphragms, guide bushings, seat ring, and valve plugcould be greatly reduced.
Maintenance
Before disassembly or removing thecontrol valve from the line, isolate it fromthe pressure system and release all thepressure from the control valve.
Due to normal wear, parts must be periodically in-spected and replaced if necessary. The frequency ofinspection depends on the severity of the service.
Main Valve Disassembly
Type 92BKey numbers listed are shown on the body assemblydrawing, figure 10.
1. Remove all tubing.
2. Mark the outside edge of the body and diaphragmcase flanges with assembly marks to ensure properassembly. Remove bolts from diaphragm case and liftoff the case. On cast iron body sizes 1-1/2 through4-inch, first remove the loading tubing compressioncoupling fitting from the pipe nipple.
3. Take out the diaphragm assembly which consistsof two metal diaphragms (key 60), bleed fitting(key 61), and diaphragm plate (key 59). Separate
Figure 8. Typical Type 92B Construction
W1322-3A
PIPE PLUG OR TUBE FITTING �DIRECTLY OVER ORIFICEFOR EASE OF ACCESSIBILITY
DIAPHRAGMSAND DIAPHRAGMPLATE
DIAPHRAGM CASE
GUIDEBUSHING
PILOT SPRING CASE
PILOT PRESSURESETTING SPRING
BELLOWS ANDBELLOWSRETAINER
LOWER SPRING SEAT
ORIFICE
CHECK VALVE ASSEMBLY
PILOT VALVE STEMAND PLUG
VALVE STEM GUIDEPILOT VALVE SPRING
BOTTOM FLANGE
REDUCING VALVE SPRING
VALVE PLUG ANDSEAT RING
VALVE BODY
BLEED ORIFICE �EASILY CLEANED WITH WIRE
Types 92B and 92P
12
these parts by unscrewing the bleed fitting from thediaphragm plate.
4. Remove cap screws from bottom flange (key 52).Take off bottom flange. The valve plug (key 56) andspring (key 57) will drop out.
5. Pull the seat ring (key 58), if it shows signs of wearand needs to be replaced. Drive the upper guidebushing (key 53) from the body (key 51) and pull thelower guide bushing from the bottom flange (key 52) ifnecessary.
Type 92PKey numbers listed are shown on the body assemblydrawing, figure 17.
1. Isolate the valve by closing the upstream and down-stream block valves. Shut the valve in the control line.
2. Blow down the isolated line to remove pressure inthe main valve.
3. Shut down the manual loader and disconnect tubingfrom the inlet in the upper diaphragm casing.
4. Remove the bolts from the diaphragm case and liftoff the upper half.
5. Take out the diaphragm assembly which consists oftwo metal diaphragms (key 10), a travel stop (key 11),and a diaphragm plate (key 20). Separate these parts byunscrewing the travel stop from the diaphragm plate.
6. Remove the cap screws from the bottom flange (key2). The valve plug (key 6) and spring (key 7) will nowdrop out.
7. Pull the seat ring (key 8), if it shows signs of wearand needs to be replaced. Drive the upper guide bushing(key 3) from the body (key 1) and pull the lower guidebushing from the bottom flange (key 2) if necessary.
Pilot DisassemblyType 92B Pilot OnlyKey numbers listed are shown on the appropriate pilotassembly drawing, figures 11, 12, 13, or 14.
1. Remove pilot from main valve by unscrewing itfrom the mounting nipple or unscrewing the nipple frommain valve.
2. Relieve the spring compression by turning the setscrew (key 15) counterclockwise after loosening hexnut (key 16).
3. Remove the casing cap screws. Take off the springcase, and remove upper spring seat, spring, lowerspring seat, two diaphragms, and the diaphragm gasket.Note that in a low pressure pilot (figure 11), the lowerspring seat and the diaphragm plate are both parts ofthe diaphragm plate assembly (key 24) and are pinnedtogether.
4. Unscrew the bellows retainer (key 8) from the pilotbody. Take out the bellows and the valve stem (keys 9and 7).
5. Unscrew the valve plug guide (key 2). The valveplug (key 4), the valve plug spring (key 3), and thestrainer screen (key 77) will come out with the guide.
6. Unscrew the orifice (key 5), if necessary.
7. Remove the check-valve assembly (key 75) with ascrewdriver after having removed the pipe plug
Figure 9. Type 92B High Pressure Pilot Exploded View
Table 5. Type 92B Main Valve Torques in Ft-Lbs (N�m)
(key 74). Be sure the check-valve is not clogged.Replace the entire check-valve assembly, if necessary.The check valve assembly should not be disassembledin the field, because its setting is made at the factoryand will be lost by disassembling.
Main Valve Reassembly
Type 92B (figure 10)Inspect all internal parts for excessive wear or damage.Use new parts when necessary (see table 5 for torquevalues). Reassemble the main valve as follows:
1. If removed, install guide bushings (key 53) in thebody (key 51) and bottom flange (key 52).
2. Apply high temperature thread sealant to seat ringthreads. Screw in the seat ring (key 58) (see table 5 fortorque values).
3. Install valve plug (key 56) and its spring (key 57).
4. Use new bottom flange gasket (key 54) and replacethe bottom flange (key 52). Lubricate and replace capscrews (key 55) (see table 5 for torque values).
5. Make up the diaphragm assembly by lubricatingand then screwing the bleed fitting (key 61) into thediaphragm plate (key 59) (see table 5 for torque val-ues), and clamping the diaphragm (key 60) in place.
Table 6. Type 92P Main Valve Torques in Ft-Lbs (N�m)
6. Place the diaphragm assembly on the body andreplace the diaphragm case (key 62). Make sureassembly marks line up. Lubricate and replace capscrews and nuts (keys 63 and 64) (see table 5 forproper torque values). On cast iron bodies, install theloading tubing compression coupling fitting on the pipenipple (sizes 1-1/2 through 4-inch).
7. Reconnect all tubing after the pilot is mounted.
Type 92P (figure 17)Inspect all internal parts for excessive wear or damageand replace with new parts when necessary. Reas-semble the main valve as follows (see table 6 fortorque values):
1. If removed, install guide bushings (key 3) in thebody (key 1) and bottom flange (key 2).
2. Apply high temperature thread sealant to seat ringthreads. Screw in the seat ring (key 8) (see table 6 fortorque values).
3. Install the valve plug (key 6) and its spring (key 7).
4. Use new bottom flange gasket (key 4) and replacethe bottom flange (key 2). Lubricate and replace capscrews (key 5) (see table 6 for torque values).
5. Make up the diaphragm assembly by placing thediaphragms between the diaphragm plates and clamp-ing them together with the travel stop.
6. Place the diaphragm assembly on the body andreplace the diaphragm case. Lubricate and replace capscrews (key 13) and nuts (key 14) (see table 6 fortorque values).
7. Reconnect the line from the manual loader.
Type 92B Pilot Reassembly(figure 11 or 12)Inspect all internal parts for excessive wear or damage.Use new parts wherever necessary. Reassemble thepilot as follows (see table 7 for torque values):
1. Apply high temperature thread sealant to the orificethreads. Screw in the orifice (key 5) (see table 7 fortorque values).
2. Place valve plug spring (key 3), the valve plug(key 4), and the strainer screen (key 77) in the valveplug guide (key 2). Apply high temperature threadsealant to the plug guide threads. Screw guide intobody (key 1) (see table 7 for torque values).
3. Place valve stem (key 7) in the body, smallerdiameter first.
4. Apply high temperature thread sealant to bellowsretainer threads. Place bellows (key 9) in body andsecure in place by installing the bellows retainer (key 8)(see table 7 for torque values).
5. Use new diaphragm gasket (key 18) and put twodiaphragms (key 10) in place on the body with raised,preformed centers toward spring case.
6. Stack the lower spring seat (key 11), spring(key 12), and upper spring seat (key 13) on the dia-phragm and install the spring case. Note that on the lowpressure pilot, the lower spring seat and diaphragmplate are part of a subassembly.
7. Lubricate and replace casing cap screws (key 17).
8. Mount pilot on main valve and install all tubing.
To Clean Pilot Strainer AssemblyRemove the valve plug guide (key 2). The valve plug(key 4), the valve plug spring (key 3), and the strainerscreen (key 77) will come out with the guide. Inspectand clean or replace as required. Key numbers arereferenced in figure 11 or 12.
To Clean Bleed FittingIf the 5/64-inch diameter hole in the bleed fitting (key61) becomes plugged, it can be cleared by running awire through it. To gain access to this hole, first isolatethe valve and relieve all pressure. Then remove eitherthe tubing and fitting or the pipe plug from the top of thediaphragm case. Clear the hole, replace the case fittingand resume normal operation. Key numbers arereferenced in figure 10.
Types 6492HM and 6492HTM PilotsThese procedures are to be performed if inspecting,cleaning, or replacing any pilot parts, or of cycling,erratic control, or too high or too low an outlet (control)pressure is noted. Perform only those procedures inthis section required to correct the problem. Keynumbers are referenced in figure 18.
Note
Before performing any maintenance,loosen the hex nut (key 16), if used, andturn the adjusting screw (key 15) counter-
Types 92B and 92P
15
clockwise until all compression isremoved from the control spring (key 12).Remove the pilot from the pipe nippleand connectors (keys 22 and 78,figure 20).
1. Unscrew the plug guide (key 2). Remove thescreen (key 77), plug (key 4), plug spring (key 3), andstem (key 7). Unscrew the orifice (key 5). Examinethe orifice and plug seating surfaces for damage.
2. Clean and replace parts as necessary. Apply hightemperature sealant to the orifice threads. Thread theseat ring into place and tighten using 19 to 25 foot-pounds (26 to 34 N�m) of torque.
3. Handle the parts carefully, and place the plugspring (key 3) in the plug guide (key 2). Slide the plug(key 4) over the spring and into the plug guide. Placethe screen (key 77) onto the plug guide. Place thestem (key 7) in the center hole of the plug guide.Apply sealant to the plug guide threads, and screw theguide plus attached parts into the body (key 1).
4. Remove the pipe plug (key 74). Then remove thepipe plug (key 94). Clean and replace the pipe plug asnecessary.
5. Apply high temperature sealant to the threads ofthe pipe plug (key 94) and install into the body (key 1).
6. Apply high temperature sealant to the threads ofthe pipe plug (key 74). Install into the body (key 1).
7. Remove the cap screws (key 17), spring case(key 14), control spring (key 12), and upper spring seat(key 13) from the body (key 1).
8. Remove the lower spring seat (key 11), dia-phragms (key 10), and diaphragm gasket (key 18) fromthe body. Inspect and clean the diaphragm gasket.Replace if necessary.
9. Unscrew the bellows retainer (key 8) and removethe bellows (key 9). Replace worn parts as necessary.Apply high temperature sealant to the bellow retainerthreads. Install the bellows and bellows retainer.Tighten the bellows retainer using 19 to 25 foot-pounds(26 to 34 N�m) of torque.
10. Install the diaphragm gasket. Install both dia-phragms with their raised performed centers facingtoward the spring case.
11. Lubricate the upper spring seat and the exposedthreads of the adjusting screw. Install the lower springseat (key 11), control spring (key 12), upper springseat (key 13), and spring case (key 14). Insert and
tighten the cap screws (key 17) in a crisscross boltingpattern using 12 to 18 foot-pounds (16 to 24 N�m) oftorque.
Parts OrderingEach Type 92B valve is assigned an FS or serialnumber. It can be found stamped on the nameplateattached to the spring case of the pilot.
Each Type 92P valve is assigned an FS or serialnumber. This can be found stamped on the nameplateattached to the lower diaphragm case.
Refer to the FS or serial number and the complete partnumber when ordering spare parts or requesting techni-cal advice from your Fisher Sales Representative orSales Office.
Types 92B and 92P
16
1. Recommended spare part
Key Description Part Number
51 Valve Body Assembly (includes body withseat ring - key 58 and guide bushing - key 53)Cast IronNPT1-inch (DN 25) 3H5846000B21-1/2-inch (DN 40) 3H2748000B22-inch (DN 50) 3F2497000B2
11 Lower Spring Seat, AluminumHigh pressure 1J914008012High temperature 14B9948X012
Key Description Part Number
12 Spring, Plated SteelLow pressure pilot2 to 6 psig (0,14 to 0,41 bar) 1E3956270225 to 15 psig (0,34 to 1,0 bar) 1D74552714213 to 25 psig (0,90 to 1,7 bar) 1E395727192
High pressure pilot15 to 30 psig (1,0 to 2,1 bar) 1E39562702225 to 75 psig (1,7 to 5,2 bar) 1D74552714270 to 150 psig (4,8 to 10,3 bar) 1E395727192
High temperature pilot15 to 100 psig (1,0 to 6,9 bar) 14B9943X01280 to 250 psig (5,5 to 17,2 bar) 14B9942X012
13 Upper Spring Seat, Plated SteelLow/High pressure 1D667125072High temperature 14B9951X012
14 Spring CaseCast Iron, Cast IronLow pressure 3J496319012High pressure 2J496219012
10 Diaphragm (2 required) 1E39583601211 Lower Spring Seat
Type 6492HM 1J914008012Type 6492HTM 14B9948X012
12 SpringType 6492HM10 to 30 psig (0,69 to 2,07 bar) 1E39562702225 to 75 psig (1,72 to 5,17 bar) 1D74552714270 to 150 psig (4,83 to 10,3 bar) 1E395727192
Type 6492HTM15 to 100 psig (1,03 to 6,9 bar) 14B9943X01280 to 250 psig (5,52 to 17,2 bar) 14B9942X012
13 Upper Spring SeatType 6492HM 1D667125072Type 6492HTM 14B9951X012
14 Spring CaseSteelwith standard adjusting screw 2L416322012with sealed adjusting screw 2L442022012
Stainless Steelwith standard adjusting screw 2L416333092with sealed adjusting screw 244420X0012
39B3357
1. Recommended spare part
Key Description Part Number
13 Cap Screw, Plated Steel1-inch (DN 25) (12 required) 1A4130240521-1/2 and 2-inch (DN 40 and 50) (12 required) 1A4175240523 and 4-inch (DN 80 and 100) (16 required) 1A427824052
14 Hex Nut, Cadmium Plated Steel1-inch (DN 25) (12 required) 1A4132241221-1/2 and 2-inch (DN 40 and 50)(12 required) 1A4176241223 and 4-inch (DN 60, 80, and 100)(16 required) 1A420124122
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