Patent ID: 6053202
Filing Date: 2000-04-25
Classification: E21B,F15B,Y10T

Abstract:
A fail-safe closure apparatus for a process valve actuator, which includes a piston with an opening chamber on one side of the piston and a closing chamber on an opposite side of the piston, comprising:a supply source of pressurized fluid for controlled application of pressurized fluid to said opening chamber;an accumulator source of pressurized fluid for controlled application of pressurized fluid to said closing chamber;a first control means including a first control valve having active and passive positions for directing pressurized fluid from said supply source to said opening chamber of said actuator when in said active position and for venting said opening chamber of said actuator when in said passive position; anda second control means including a second control valve having active and passive positions for preventing venting of pressurized fluid from said accumulator source and allowing accumulator pressurized fluid to be applied to said closing chamber of said actuator when in said passive position and for venting said closing chamber of said valve actuator when in said active position.