Port 2: InletPort 1: Reduced PressurePort 3:DrainAdjustment ScrewHeavy SpringPoppet SeatPilot PoppetLight SpringMain PoppetBalance OrificeLight SpringMain PoppetHeavy SpringPilot PoppetPilot Drain ValvePort 2: InletPort 1: Reduced PressurePort 3: DrainPort 2: InletPort 1: Reduced PressurePort 3: DrainBalance OrificePilot Drain ValvePilot Drain ValvenumSpring Setting:numPressure:Detailed Schematic SymbolSimplified Schematic SymbolnumPressure:Low PressureHigh PressureVacuum PressureDrain PressureColors LegendMedium Pressure