Manually reset control valve for a fluid actuator

摘要

A manually reset control valve (28) to control the flow of fluid to a fluid actuator (22) in a safety system for closing a valve in a main flowline (10) upon the reaching of predetermined high and low pressures in the main flowline. The control valve includes an elongate housing having a supply port (26) and a bleed port (124) for the actuator, and a sensing port (34) for monitoring the fluid pressure in the main flowline. The valving in the bore of the housing includes a pressure sensing valve mechanism (42) and a control fluid valve mechanism (44). Pressure sensing valve mechanism (42) includes a high pressure spring (94) responsive to a predetermined high pressure in the flowline to actuate the valving and a low pressure spring (58) responsive to a predetermined low fluid pressure in the flowline to actuate the valving for bleeding the actuator. The control fluid valve mechanism (44) includes a piston (110) movable between supply and vent positions in response to the actuation of the sensing valve mechanism (42). A manual gripping knob (108) on an outer end of the control fluid valve mechanism (44) is pushed for resetting the valving after actuation and a lost motion connection between the pressure sensing valve mechanism (42) and the control fluid valve mechanism (44) permits valve mechanism (44) to be pushed in and reset with a minimum of force.