FIRE SAFE BUTTERFLY VALVE

摘要

Disclosed is a butterfly valve comprising sealing means for a movable valve member in the form of a resilient high temperature destructible sealing ring and a resilient high temperature indestructible seating ring, both of which are normally preloaded into radial sealing engagement with the movable valve member. The high temperature destructible seating ring is the primary seal and the high temperature indestructible seating ring being a backup seal in one direction of flow and the high temperature indestructible seating ring is the primary seal in the opposite direction of flow. Upon destruction of the high temperature destructible seating ring, the high temperature indestructible seating ring is so retained and configured to provide bidirectional seating.