VALVE POSITIONING SYSTEM WITH BLEED PREVENTION

摘要

A valve positioner system (12) with zero bleed at steady state is disclosed. The system has a pilot valve (30), the operation of which is controlled by an electronic circuit (34) powered from a signaling and power connection of a positioner device. A plurality of pneumatic valves (32) are activated and deactivated by the pilot valve to control a valve actuator (14). With varying configurations and arrangements of normally open or normally closed pilot valves and pneumatic valves, fail freeze and fail safe operations are contemplated. The activation and deactivation of the pilot valve is controlled by an electronic circuit that monitors a valve position signal.