PRESSURE REDUCING VALVE CONTROL

摘要

An improved pilot valve assembly (14) for hydraulically controlling a pressure reducing valve (12) to maintain and further vary the outlet pressure (P2) of the pressure reducing valve (12) in response to increased flow (f) through the valve (12). The pilot valve assembly (14) comprising first and second movable valve members (100,102). The first and second moveable members (100,102) being acted on by a velocity head pressure sensed by a downstream Pitot tube (90) and a downstream outlet pressure (P2) in a balanced arrangement such that they move in response to both the velocity head and downstream pressure (P2) to open and close the pilot valve (14) and so main valve (12) to both maintain and vary the outlet pressure (P2).