Fire safe butterfly valve - has resilient high-temp. destructible seal and seat ring pre-loaded against valve

摘要

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