Patent ID: 6886808

Claim:
A drain valve for placement in the wall of a vessel to drain its contents, said valve comprising: a body having an inner end, an outer end, a central axis, an outer wall, an inner peripheral wall defining a central passage which extends from end to end of the body, an inlet port adjacent to said inner end, a first and a second peripheral sealing surface on said inner peripheral wall, said sealing surfaces being spaced apart by a recess between them, and a thread on said body adjacent to its outer end to receive a collar for mounting the body in an opening through the wall of the vessel; a plunger in said passage, extending axially and slidably fitted therein, said plunger having a central axis coaxial with the axis of said passage, a first peripheral sliding seal so disposed and arranged as to make a fluid sealing fit with said first peripheral sealing surface over a range of its movement to close the valve to flow, and to pass beyond it to permit said flow, a second peripheral seal so disposed and arranged as to seal with said second peripheral sealing surface, a flow bore in said plunger extending from its outer end to a flow port opening onto the outside of the plunger between said sliding seals; whereby with the valve mounted to the vessel and the plunger pressed inwardly so the first sliding seal and first peripheral sealing surface engage, there is no flow through the valve, but when the plunger is moved outwardly so the first sliding seal moves away from said first peripheral sealing surface, water can flow to the recess and into said flow port and out of the plunger.