Gate valve having a secondary seal, wherein the gate forms a metal to metal seal with the seat and wherein {HEAD ~ a resilient seal} is moved toward {TAIL ~ the gate} when the gate is in closed position to form a secondary fluid tight seal with the gate, whereby leakage past the gate is effectively prevented 
Gate valve having a secondary seal , wherein the gate forms a metal to metal seal with the seat and wherein { HEAD ~ a resilient seal } is moved toward { TAIL ~ the gate } when the gate is in closed position to form a secondary fluid tight seal with the gate , whereby leakage past the gate is effectively prevented
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