Abstract: A fire-safe valve actuator which cooperates with a bolted bonnet type valve to define a bolt chamber with an exterior shroud supporting the actuator housing and providing a substantially 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 any substantial torque being applied to the actuator stem. Similarly, 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.

Abstract: A gate valve is provided having a recess formed in the upstream portion of the gate and in intersecting relation with the gate port. The gate recess cooperates with a registering recess formed in the downstream portion of the upstream seat to develop a large flow passage as compared to a small flow passage defined by the interrelationship of the gate port with the downstream seat. Fluid laden with erosive material will flow through the larger dimension gate/seat opening between the gate and upstream seat at low velocity, as compared to high velocity flow through the opening defined between the gate and the downstream seat. This low velocity flow, impinging upon the downstream seat, results in minimized erosion of the downstream seat during opening and closing movement of the valve.

Abstract: A fire-safe valve actuator which cooperates with a bolted bonnet type valve to define a bolt chamber with an exterior shroud supporting the actuator housing and providing a substantially 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 any substantial torque being applied to the actuator stem. Similiarly, 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.