Valtek Flow Boosters.pdf - PRO-QUIP

Valtek Flow BoostersGENERAL INFORMATIONThis bulletin is designed to assist in installing, adjusting,troubleshooting, and performing maintenance asrequired for the Valtek ® Flow Booster. Product usersand maintenance personnel should thoroughly reviewand follow the instructions contained in this bulletin priorto the operation of the flow booster. If there are anyquestions concerning the procedures outlined in theseinstructions, contact your Valtek representative.Installation, operation, maintenance instructions onValtek actuators and valves are contained elsewhere;reviewing those instructions is suggested before maintainingor troubleshooting a flow booster.To avoid possible injury to personnel or damageto valve parts, WARNING and CAUTIONnotes must be strictly adhered to. Modifyingthis product, substituting non-factory parts,or using maintenance procedures other thanoutlined could drastically affect performance,be hazardous to personnel and equipment,and may void existing warranties.Principle of OperationThe Valtek booster is a pressure-balanced instrumentthat increases actuator stroking speeds when largeinput-signal changes are received.Through the adjustment of the bypass valve, sensitivityto a signal change can be increased or decreased. Asmall input signal to the booster will not create a pressuredifferential across the diaphragm assembly sufficientto cause booster actuation. Rather, the air passesthrough the bypass porting while the poppet valvesremain tightly shut to prevent unnecessary air use.A sudden, large input-signal change will create a pressuredifferential across the diaphragm assembly, forcingthe poppet valve down, and permitting high air flowinto the control valve actuator.Rev. 11/94 Valtek No. 10076933This high air flow continues until the pressure differencebetween the control valve actuator and the inputsignal fall within the deadband limits of the booster.Likewise, when the booster is used to exhaust a controlvalve actuator, the pressure imbalance across thediaphragm assembly forces it up off the upper poppetvalve and the air exits the booster between the diaphragms.For on/off control valves, the bypass valvecan be virtually closed to maximize the stroking speed.InstallationWhen installing the flow booster, refer to Figure 1, andproceed as follows:WARNING: Before installing or performing anymaintenance on the flow booster, shut off the airpressure to the supply line and the input signal line,and slowly release any internal pressure in theactuator and booster. High pressures not releasedfrom the booster supply lines may cause personalinjury or damage to the flow booster.WARNING: Shutting off the air supply to the positionerand hence control valve can cause the valveto move to its fail position or be disabled, causingexcessive pressures to build up in the system.This, in turn, may result in the system failing,causing injury to equipment or personnel.Generally the flow booster is nipple mounted on theactuator with 3 /4-inch NPT pipe. However, some systemsrequire multiple boosters or special configurationsthat may require the booster to be mounted witha bracket. If special mounting is needed, contact yourlocal Valtek representative or the factory for assistance.The supply port connection (marked SUP) and theactuator port connection (marked CYL) are both3/4-inch NPT. The input signal port connection (markedSIGNAL) is a 1 /4-inch NPT. A pipe sealant compoundshould be applied to all connections prior to installation34-1

Bypass Valve O-ring(Item No. 14)Bypass Valve(Item No. 9)Bypass Valve Nut(Item No. 13)Upper Spring Cap(Item No. 18)Input Signal PortHousing Bolt(Item No. 12)Housing Cover(Item No. 2)Upper Spring(Item No. 17)Upper Diaphragm(Item No. 8)Vent Ring(Item No. 3)Poppet(Item No. 4)End Plug O-ring(Item No. 15)SupplyOutputHousing(Item No. 1)Lower DiaphragmAssembly(Item No. 7)End Plug(Item No. 10)E0114Lower Spring Cap(Item No. 21)Lower Spring(Item No. 11)Figure 1: Flow BoosterNOTE: Item numbers correspond directly to the booster's bill of materials; refer to it for specific numbers.to prevent leaks. All piping and connection adaptersshould be rated at least as high as the maximum ratedbooster pressure, 150 psi (10.3 Bar). The flow boosteris designed to function properly in any position. Figures2 and 3 show possible installation configurations for twotypes of actuators.The supply air to the flow booster does not requireregulation if the maximum rated pressure of the actuatoror the flow booster, 150 psig (10.3 Bar), is notexceeded. All air flowing into the flow booster should bedry and filtered to ensure a clean and non-corrosivemedium.WARNING: The exhaust ports on the flow boosterexhaust air at extremely high velocities. Harm toindividuals or equipment can result if positionedtoo closely to the exhaust ports.After the flow booster has been installed, it may need tobe adjusted for optimal performance. Refer to “AdjustingFlow Booster Operation” section to make theseadjustments correctly.Adjusting Flow Booster OperationOnce the flow booster is mounted properly, the bypassvalve may need to be adjusted for proper operation.This should be done prior to making any positionercalibrations. To make this adjustment, refer to Figure 1,and proceed as follows:1. Turn the bypass valve counter-clockwise three orfour turns from its closed position.2. Calibrate the positioner according to positionerinstructions.3. Turn the bypass valve clockwise until the flowbooster actuates with large positioner inputchanges but does not actuate with small positionerinput changes. This is done by stroking the controlvalve and adjusting the bypass valve slightly untilthe desired dynamics is acheived. Turning thebypass valve clockwise increases booster actionand overshoot.34-2

CAUTION: Cycling the control valve can disruptthe process. Care must be used to ensurethis disruption will not adversely affect theprocess.4. Once the bypass valve has been optimally set,the bypass valve nut should be tightened downto prevent the bypass valve from turning duringoperation.NOTE: The flow booster is bench calibrated andmay need to be re-adjusted once the valve is in theprocess.NOTE: When two or more flow boosters are usedon one actuator, all bypass valves on one side ofthe actuator can usually be set the same.NOTE: If the control valve is used for only on-offoperation, the bypass valve should be turnedclockwise until it is nearly closed to maximizestroking speed.MAINTENANCEAlthough the flow booster is designed to provide a longservice life, periodic maintenance is required to extendthe booster's life. Some parts in the flow booster mayneed to be replaced periodically. These parts mayinclude: diaphragms, poppet valve, O-rings andsprings. If the lower diaphragm needs replaced, theentire lower diaphragm assembly (Item No. 7) must beordered.WARNING: Before performing any maintenance onthe flow booster, shut off the air pressure to thesupply line and the input signal line and slowlyrelease any internal pressure in the actuator andbooster. High pressures not released from thebooster supply lines may cause personal injury ordamage to the flow booster.WARNING: Shutting off the air supply to the positionerand hence control valve can cause the valveto move to its fail position or be disabled, causingexcessive pressures to build up in the system.This, in turn, may result in the system failing, causinginjury to equipment or personnel.Replacing The Diaphragm AssemblyTo replace the diaphragms, refer to Figures 1 and 4,and proceed as follows:1. With the flow booster in an upright position,unscrew the six cap screws. Lift the cover off theupper diaphragm. (If the cover adheres to thediaphragm, gently tap the cover loose with a rubbermallet under the bypass valve protrusion.)2. Remove the upper diaphragm and inspect fordamage or wear. If necessary, replace the upperdiaphragm.3. Remove the lower diaphragm assembly and inspectfor damage or wear. Particular attentionshould be given to where the bottom diaphragmcontacts the housing limit stops. Also, inspect theretaining rings for tightness of fit. If necessary,replace this assembly.4. Reinstall the lower diaphragm assembly.NOTE: Clean the diaphragm mating surfacesthoroughly before replacing the diaphragms.5. The poppet must be centered in the housing. Thisis ensured by pressing down on the lower diaphragmassembly slightly and then releasing pressurewhile holding the lower diaphragm assemblycentered. This procedure may need to be repeatedto center the poppet in the housing.Be certain the lower diaphragm assembly is centeredon the housing and the bypass hole anddiaphragm bolt holes line up with the appropriatehousing holes.NOTE: The lower diaphragm assembly and housinghave the same outside diameter dimension andshould be flush when installed correctly.6. Reinstall the vent ring, aligning it with the appropriatehousing holes.7. The distance between the lower poppet seat lineand the upper poppet seat line is important tobooster performance. To check this distance,place a straight edge across the middle of the ventring. The aluminum seat should be on the sameplane, within ±.030 inch (±762 mm), with the ventring. If it is not, the poppet may not be centered(see step 5), or it may be worn (see “Replacing thePoppet Valve” section).8. Reinstall the upper diaphragm and apply an antiseizelubricant inside the cover spring bore.9. Place the cap and spring on the center of thediaphragm, and replace the cover on the diaphragm(be certain spring cap slides into the bore).CAUTION: To ensure proper flow booster operation,be certain the bypass hole in the diaphragmsorients properly with the bypassholes in the housing, vent and cover.10. Replace the six housing cap screws and tightenthem finger tight. Be certain that the housing, ventand cover are concentric with each other beforetightening the bolts with a wrench in a crisscrosspattern.CAUTION: Care should be taken to not overtightenthe housing cap screws. Over-tighteningmay damage the diaphragms, preventingthe booster from operating properly.34-3

Piston ActuatorFlow BoosterSupplyFlow BoosterOutput 2Output 1PositionerSignalSupplyE0115Figure 2: Typical Flow Booster Installation Schematic on Cylinder ActuatorReplacing the Poppet ValveIf the urethane seat on the poppet is cut, damaged orseverely indented, the poppet must be replaced. To dothis, refer to Figures 1 and 4, and proceed as follows:1. Turn the flow booster upside down and remove theend plug. Note that the poppet valve, lower springcap and lower spring may freely drop from thebooster. Check the end plug O-ring for wear ordamage. Replace if necessary.2. Remove the lower spring, lower spring cap and thepoppet valve.3. Before placing a new poppet valve in the boosterhousing, apply an anti-seize lubricant to the insidebore of the end plug. Re-install the lower springand the lower spring cap. Place a new poppet intothe hole of the lower spring.4. While holding the flow booster in an upright position,carefully insert the poppet and end plug assemblyinto the housing.5. Tighten the end plug.34-4

Flow BoosterOutput 2(plugged)Output 1PositionerDiaphragmActuatorSignalSupplySupplyE0116Figure 3: Typical Flow Booster Installation Schematic on Diaphragm ActuatorTable I: Flow Booster SpecificationsInput Signal Range Maximum: 150 psig (10.3 Barg)(Same as positioner output)Supply Pressure Up to 150 psi (10.3 Bar)Ranges(check actuator rating)Nominal Deadband 5.5% of input signal spanAmbient -40 to 165 O F (-40 to 74 O C)Temperature LimitsSupply Air -40 to 165 O F (-40 to 74 O C)Temperature LimitsMaximum C VSupply 5.0Exhaust 3.0ConnectionsSignal1/4-inch NPTSupply, Output3/4-inch NPTNet Weight4.9 lbs (2.2 kg)Table II: Standard Materialsof ConstructionComponentBodyEnd PlugDiaphragmAssemblyPoppetNeedle ValveSpringsSpring CapBolts, NutsStandard MaterialsAnodized aluminumNickel plated brass(electroless)Anodized aluminum andBuna-N/Nylon diaphragmsStainless steel andpolyurethaneStainless steelStainless steelStainless steelStainless steel34-5

Housing Bolt(Item No. 12)Housing Cover(Item No. 2)Upper Spring(Item No. 17)Bypass Valve O-ring(Item No. 14)Bypass Valve(Item No. 9)Spring Cap(Item No. 18)Bypass Valve Nut(Item No. 13)Upper Diaphragm(Item No. 8)Vent Ring(Item No. 3)Lower DiaphragmAssembly(Item No. 7)Housing(Item No. 1)Lower Spring(Item No. 11)End Plug(Item No. 10)Poppet(Item No. 4)Lower Spring Cap(Item No. 21)End Plug O-ring(Item No. 15)Figure 4: Flow Booster – Exploded ViewE011234-6

Flow Booster TroubleshootingProblem Probable Cause Corrective ActionValve overshoots 1. Bypass porting is too restrictive 1. Turn the bypass valve counterclockwiseuntil overshoot is corrected2. Diaphragm not aligned 2. Disassemble the flow booster and alignproperly over bypass porting both diaphragms over their appropriateholes3. Obstruction in the bypass 3. Disassemble the flow booster andportingclean out the portingValve is over-damped 1. Bypass porting is not restrictive 1. Turn the bypass valve clockwise untilenoughover-damping is corrected2. Diaphragms are damaged and 2. Replace the diaphragmsleakingLoss of sensitivity 1. Spring caps not sliding properly 1. Apply an anti-seize lubricant to thesurface of the spring bore2. Obstruction in the signal port 2. Remove obstruction in signal portBooster continuously 1. Bypass needle valve is closed 1. Adjust bypass valve (see “AdjustingexhaustingFlow Booster Operation” section.)2. Lower diaphragm is leaking air 2a. Disassemble flow booster and pressdown on retaining ring or replaceretaining ring2b. Replace the lower diaphragm3. Poppet seating surfaces are 3a. Replace the poppet valve and cleandamagedout obstructions that may havecaused the damage3b. Replace booster body or upperdiaphram assembly if their seats aredamaged4. Positioner pressure imbalance 4. Refer to the appropriate positionerproblemmaintenance instructions5. Aluminum seat/upper poppet 5a. Replace the retaining ring under thevalve not sealinglower diaphragm5b. Align the lower diaphragm with thehousing bolt holes6. Actuator is leaking air 6. Repair actuator as neededExcessive air 1. Air leakage over or under the 1a. Tighten the six capscrews evenlyconsumption diaphragms 1b. Clean the diaphragm surfaces1c. Replace the diaphragm(s)2. Air leakage past the bypass 2. Replace the O-ring on the bypassvalvevalve and lubricate the O-ring3. Air leakage past the end plug 3a. Tighten the end plug3b. Replace or straighten the O-ring4. Air leakage at NPT connections 4a. Tighten connections4b. Apply sealing compound/tape34-7