Patent ID: 7552743

Claim:
A fluid flow shutoff valve, comprising: a housing having an inlet, an outlet and a passage therebetween, the passage including a valve seat thereabout, a first, cylindrical section and a second section; a valve element slidably mounted in the passage between a first upstream position and a second downstream position, the valve element including a cavity opening toward the inlet, at least one restrictive orifice in the valve element located at a downstream end of the cavity and extending through a wall of the valve element from the cavity to the periphery of the valve element, and a sealing surface located at a downstream end of the valve element, the sealing surface being engageable with the valve seat to prevent flow through the valve; and a spring in compression between the housing and the valve element biasing the valve element toward the inlet and away from the valve seat; wherein when the valve element is in the first position the sealing surface is displaced from the valve seat and the first cylindrical section covers the restrictive orifice, thereby preventing flow through the valve, and when the valve element is in the second position the sealing surface engages the valve seat and prevents flow through the valve and the restrictive orifice is open into the second section.