Importance

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Abstract

A pilot operated safety relief valve assembly including a main safety relief valve (14) and a pilot valve (36) connected directly to the relief valve (14) is disclosed. Main safety relief valve (14) has a planar mounting face (76) in contact relation with opposed mating mounting face (78) of the pilot valve (36). Dome ports (72 and 84) in contacting planar faces (76, 78) are in alignment with each other without any tubing therebetween. Exhaust ports (74 and 86) in contacting planar faces (76, 78) are in alignment with each other without any tubing therebetween. Inlet sensing ports (75D, 75E, 65D, 65E) as shown in the embodiments of FIGS. 9 and 10 in contacting planar faces (76D, 76E, 78D, 78E) are in alignment with each other without any tubing therebetween. A fluid pressure pickup fitting (48) has a port (118) which communicates with the fluid passage (50) to the pressure vessel. A test connection (120) is connected to the fluid pressure pickup fitting (48). A shuttle valve (122) permits the pilot valve (36) to be responsive to the fluid pressure in inlet fluid passage (50) at all times. An embodiment of FIGS. 4-6 provides a back flow preventer shuttle valve (121A) in pilot valve body (38A) which blocks inlet fluid flow from inlet fluid passage (100A) to the main valve dome passage (72A) to prevent opening of the main valve member when fluid pressure in the main valve outlet chamber (52A) is higher that the fluid pressure in the fluid inlet passage (100A).

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First Claim