Abstract: A safety relief system for a valve in a vent or a main flowline. The safety relief system utilizes a main actuator (24) utilized primarily for a positive pressure condition and a vacuum actuator (96) in axial alignment with the main actuator (24) utilized exclusively for a negative pressure condition. The main valve member (18) has a stem (22) which extends within both actuators (24, 96) and diaphragms (26, 100) are connected to the stem (22) for movement of the valve member (18).

Abstract: A testing device (22) for a non-flowing pilot valve (20) controlling a main relief valve (13) and simulating the action of the relief valve (13). The testing device body (84) has a test fluid source (42) releasably connected thereto and includes a piston valve element (112) mounted in a valve chamber (106) for movement to an unseated vent position upon the test fluid pressure reaching a predetermined high which is usually similar to the set point operating fluid pressure at which the main relief valve (13) will actuate. For return of piston valve element (112) to a seated position after a reduction of the test fluid pressure by venting, a relatively large diameter end face (128) is exposed to fluid pressure from an intermediate fluid chamber (78) of the pilot valve (20) which is in fluid communication with the dome (14) of the pressure relief valve (13). A relatively small fluid pressure responsive area of piston (113) outwardly of small diameter O-ring (120) is exposed to test fluid pressure.

Abstract: A pressure relief device (28) removably secured to a pressure vessel (10) has a valve closure (83) including an inner valve plate (84) and an outer cover (96) thereover. A spindle (68) is secured separately to valve plate (84) and cover (96), and springs (80, 82) positioned below a tapered plug (54) urges valve closure (83) to a closed position. An elastomeric O-ring (108) between plate (84) and cover (96) forms the primary seal and may be removed and replaced while valve plate (84) remains in a seated closed position.

Abstract: For use in connecting a measuring instrument across a pipeline portion having an orifice therein to create a pressure drop whereby static and differential pressure signals are formed, a unitized connector apparatus is set forth in the preferred and illustrated embodiment and includes an elongate rectangular body having a lengthwise axial passage drilled therethrough. Additional passages intersect the long passage at the ends, and suitable valve means are included near the ends thereof. The structure is a unitized structure adaptable for quick and prompt installation with a minimum of connections made to the measuring instrument. Moreover, the structure is roddable, that is, the passages can be easily cleaned by means of a rod inserted therethrough.