APPLICATIONS: Regulation of inlet pressure to gas compressors. Control of supply or distribution system pressures. PRESSURE RANGE: Upstream: 50 psig to 500 psig Downstream: 50 psig to 500 psig PILOT SUPPLY PRESSURE: 40 psig NOTE: For upstream pressure less than 50 psig use outside source of supply to operate MOTOR VALVE DIAPHRAGM. OPERATION: The Pilot assembly and Motor Valve Stem Assembly (Crosshatched) are the only moving units in the regulator. The PILOT PLUG consists of two stainless balls rigidly connected together. The upper seat for the PILOT PLUG is the Motor Valve Diaphragm Pressure inlet (Violet to Yellow). The lower seat for the PILOT PLUG is the pressure vent (Yellow to Atmosphere). The Pilot Supply Pressure (Violet) leads the MOTOR VALVE DIAPHRAGM to provide the closing force for the Motor Valve against the Upstream Pressure. The PILOT SPRING in the bonnet loads the upper side of the Pilot Assembly and is opposed in the under side by Downstream Pressure (Blue) in the BELLOWS ASSEMBLY. Assume the PILOT SPRING is compressed with the ADJUSTING SCREW for a set pressure greater than the Downstream Pressure (Blue) in the BELLOWS ASSEMBLY. The Pilot Assembly is forced downward by the PILOT SPRING. The lower seat for the PILOT PLUG (Yellow to Atmosphere) is closed and the upper seat for the PILOT PLUG (Violet to Yellow) is open. This allows Pilot Supply Pressure (Violet) to load the underneath side of the MOTOR VALVE DIAPHRAGM to balance the pressure on the top side. Upstream Pressure (Red) acting under the motor valve seat, opens the valve. As Downstream Pressure (Blue) increases to the set pressure, the BELLOWS ASSEMBLY expands upward, compressing the PILOT SPRING and first closing the upper seat (Violet to Yellow) and then opening the pressure vent (Yellow to Atmosphere). As the MOTOR VALVE DIAPHRAGM PRESSURE (Yellow) is decreased, the PILOT SUPPLY PRESSURE acting on top of the Motor Valve Diaphragm begins to close the valve. With increase of Downstream Pressure (Blue) to the set pressure, the Pilot Assembly assumes a position in which both seats of the PILOT PLUG are closed. The intermittent bleed pilot, three-way valve action of the PILOT PLUG against its seats adjusts the Motor Valve Stem Assembly to accommodate any flow rate. The rapid but stable repositioning produces a true throttling action.
