Two stage pressure reducing valve for gas flows - large pressure reduction occurs over two sets of orifices in series

摘要

A two stage pressure reducing valve ensures that the critical pressure ratio is not exceeded thus avoiding the generation of undue noise. High pressure inlet flow (14) is to be reduced in pressure for transmission to an outlet section (16). The pressure reduction is accomplished by one sleeve (24) axially set within a fixed outer sleeve (22). The inner sleeve (24) which connects (30) with a hand actuator has a series of orifices (34) at the top end. The outer sleeve (22) has orifices located at the bottom end. In the closed position both sets of orifices are closed, thus preventing any flow. When the inner sleeve is axially displaced a pressure reduction from inlet (P1) to the intermediate chamber (42) pressure (P2) occurs, followed by a further drop over the outer sleeve orifices (32) to the final output pressure (P3). Both pressure reductions are below the critical value.