SAFETY RELIEF VALVE FOR PRESSURE VESSELS

摘要

A fluid pressure relief system for a pressure vessel (10) comprising: a nozzle (38) defining an upper valve seat (42) forming a vent (44) for the pressure vessel (10); a main valve member (46) seated on said valve seat (42) under a mechanical force (54) of a predetermined amount for holding said main valve member (46) in closed position on said valve seat (42) under normal operating fluid pressure within said pressure vessel (10). An operating rod (55) is secured adjacent one end of said main valve member (46); and a piston (74) is secured to said operating rod (55) adjacent the other end thereof. A cylinder receiving said piston (74) for reciprocable movement and defining a fluid chamber (78) adjacent one side of said piston (74) with the other side of said piston (74) is in fluid communication with the interior of said pressure vessel (10); and there is provided a vacuum valve member (60) mounted on said operating rod (55) for relative sliding movement opening under normal operating pressure within said pressure vessel (10), said vacuum valve member (60) opening upon a predetermined negative pressure within said pressure vessel (10) to permit fluid flow within said pressure vessel through said central opening of said main valve member (46).