초록 ▼

A pilot operator and a relief valve are provided in the same housing. The pilot-operating mechanism is contained partially within the main closure element of the valve and partially within the valve cap. Inlet pressure to the valve is communicated to the pilot via an access passage extending through

A pilot operator and a relief valve are provided in the same housing. The pilot-operating mechanism is contained partially within the main closure element of the valve and partially within the valve cap. Inlet pressure to the valve is communicated to the pilot via an access passage extending through the main closure element. In response to high-pressure flow from the inlet, a pilot piston moves a spacer rod through the passage and into engagement with a spring-loaded vent closure. The piston-induced movement of the rod opens the vent to relieve the pressure behind the main closure element, which in turn permits the main closure element to open and relieve the inlet pressure through the valve outlet. Opening of the main closure element terminates flow through the access passage. When the inlet pressure is sufficiently reduced, the pilot piston is unseated by the spring force re-opening the access passage to allow the pressure behind the main closure element to increase and close the main closure element. A back-flow-prevention assembly carried in the main closure element prevents reverse flow of fluids from the outlet to the inlet when the outlet pressure exceeds the inlet pressure.

대표청구항 ▼

[ What is claimed is:] [1.] A pilot-operated relief valve for relieving pressure from a vessel, comprising:an axially extending main valve closure element movable axially between closed and open positions for respectively closing and opening a discharge path from said vessel, said main valve closure

[ What is claimed is:] [1.] A pilot-operated relief valve for relieving pressure from a vessel, comprising:an axially extending main valve closure element movable axially between closed and open positions for respectively closing and opening a discharge path from said vessel, said main valve closure element having a first pressure-responsive seal area at its first axial end selectively sealing said path communicating with said vessel and a second pressure-responsive seal area at its second axial end selectively communicating with a control dome area whereby a pressure differential between said first and second pressure responsive seal areas tends to move said main valve closure element axially;a pilot-sensing passage extending through said main valve closure element between said first and second pressure-responsive seal areas for communicating the fluid pressure of said vessel to said control dome area;a sensing passage restriction body movable in response to the pressure in said vessel to a position restricting said passage whereby said main valve closure element is opened when said vessel pressure meets or exceeds a selected pressure value; anda sensing passage closure seal for preventing flow through said sensing passage when said main valve closure element is opened.