Fire-safe valve actuator - has actuator with bolted bonnet valve and exterior shroud supporting housing

摘要

The fire-safe valve actuator cooperates with a bolted bonnet valve to define a bolt chamber with an exterior shroud supporting the actuator housing and providing an imperfect barrier to prevent an external fire from coming into direct contact with the bolts or studs and nuts that connect the bonnet to the valve body. The bolt chamber may also be filled with an insulation material. The actuator may have a return spring connected to the actuator stem through a bearing so that the winding and unwinding of the spring does not result in torque being applied to the actuator stem. Any diaphragm in the actuator can be connected to the actuator stem by a bearing so that rotation of the stem will not impart torque to the diaphragm. A stop can be provided limiting outward movement of the stem under the influence of the spring.