초록 ▼

A shut off valve, of the type having a normally open main valve that closes in response to a shear force of greater than a predetermined magnitude, and a normally closed secondary valve that opens in response to a predetermined fluid pressure, wherein the main valve is contained in a first sub-housi

A shut off valve, of the type having a normally open main valve that closes in response to a shear force of greater than a predetermined magnitude, and a normally closed secondary valve that opens in response to a predetermined fluid pressure, wherein the main valve is contained in a first sub-housing and the secondary valve is contained in a separate second sub-housing, downstream from the first sub-housing. A hollow, tubular shear fitting, having an annular shear groove, has an upstream end removably coupled to the downstream end of the first sub-housing, and a downstream end removably coupled to the upstream end of the second sub-housing, where by the first sub-housing, the shear fitting, and the second sub-housing are axially aligned so that they define a continuous internal flow passage from the upstream end of the first sub-housing to the downstream end of the second sub-housing. When the shear fitting fractures at the shear groove in response to a shear force, the fragmented shear fitting can be removed from the sub-housings and replaced, without replacing the sub-housings.

대표청구항 ▼

A shut off valve assembly, comprising: a first sub-housing having a flow passage extending between an upstream end and a downstream end; a normally-open main valve, contained in the first sub-housing, that closes in response to a shear force of greater than a predetermined magnitude; biasing means f

A shut off valve assembly, comprising: a first sub-housing having a flow passage extending between an upstream end and a downstream end; a normally-open main valve, contained in the first sub-housing, that closes in response to a shear force of greater than a predetermined magnitude; biasing means for biasing the main valve toward a closed position; a second sub-housing having a flow passage extending between an upstream end and a downstream end; a normally-closed secondary valve, contained in the second sub-housing, that opens in response to a predetermined fluid pressure, and that closes the flow passage through the second sub-housing in the absence of the predetermined fluid pressure; a hollow shear fitting having an upstream and removably coupled to the first sub-housing downstream end and a downstream end removably coupled to the second sub-housing upstream end, so as to define a continuous internal fluid flow passage that is substantially unobstructed and unrestricted from the first sub-housing upstream end to the second sub-housing downstream end, the shear fitting having a weakened wall area that fractures in response to a shear force of greater than a predetermined magnitude; and locking means on the shear fitting, and coupling the shear fitting and the main valve, for locking the main valve open against the force of the biasing means, and for releasing the main valve to close in response to a shear force of greater than a predetermined magnitude; whereby the first and second sub-housings remain intact upon the fracturing of the shear fitting at the weakened wall area, so that the flow passage through the second subhousing remains closed by the secondary valve upon the removal of the shear fitting.