AXIAL FLOW VALVES

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Pilot regulatorsThese spring-loaded regulators are used to balancethe pressure applied to the control port of an AxialFlow Valve. It is actually the choice of pilot thatdetermines function (pressure reduction orbackpressure) and output pressure or relief setting.The adjustable restrictor which is an integral part ofthe AFV determines operating characteristics; lowsettings for quick opening and slow closing, highersettings for slow opening and quick closing.Types ZCS-150 and ZSC-320-150These double diaphragm regulatorsare for backpressure or pressurerelief applications. The ZSC-150provides setpoints from 1 to 225 psi,while the ZSC-320-150 has a rangeof 200 to 600 psi.Types ZSC-100 and ZSC-320-100Both of these models are doublediaphragm regulators for pressurereducing applications. The ZSC-100supplies output pressures from 1 325psi; the ZSC-320-100 has an outputrange of 200 to 600 psi.Type 1203This family of regulators isfor pressure reducingservice requiring outputpressures from 5 inchesW.C. to 5 psi.Spring force tends to hold the regulator open.This force is counterbalanced by pressureapplied to the downstream sensing chamberdiaphragm. When the downstream pressuredecreases, the regulator is opened wider,increasing flow. This produces a larger dropacross the restrictor and a decrease in controlpressure to the AFV, thereby increasing flow tosatisfy downstream demand.As long as the spring force is greater than theforce of the upstream pressure acting on theupstream sensing chamber diaphragm, theregulator is held closed. When upstreampressure increases beyond the setpoint, theregulator opens. Since the exhaust isnormally at close-to-zero pressure, a largeflow occurs through the regulator, quicklyopening the AFV to relieve the overpressurecondition.
ApplicationsSingle-stage pressure reduction. Whendownstream pressure decreases, spring forceincreases the effective opening of the pilot. Theincrease in flow produces a larger pressure dropacross the variable restrictor, reducing controlpressure to the AFV and increasing flow in theline.Tow-stage pressure reduction: psi to psi to in.W.C. When large reductions in pressure arerequired, the cut can be made in two stages.Here an American AFV and Type ZSC-100 pilotcontrol a psi to psi cut. The second stageincorporates a Type 1203 regulator to give a finaloutput pressure in the inches W.C. range.
Page 1 and 2: SB9509.3AXIAL FLOWVALVES
Page 3: Basic valve operationBecause there
Page 7 and 8: Pressure relief valve. With the ZSC
Page 9 and 10: Regulation with check valve in alte
Page 11 and 12: Sizing the American AFVfor pressure

AXIAL FLOW VALVES

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