Patent ID: 8413486

Claim:
A shut-off valve testing system, comprising: a hydraulic-pneumatic control cylinder having a pneumatic volume, a hydraulic volume, and a piston therebetween; a differential pressure transmitter communicating with the pneumatic volume and the hydraulic volume of the control cylinder; a hydraulic actuator selectively communicating hydraulically with the control cylinder, the hydraulic actuator having a loading pressure volume, an actuating pressure volume, and a piston therebetween, the hydraulic actuator further communicating with and controlling a main shut-off valve; a source of pneumatic pressure communicating with the pneumatic volume of the hydraulic-pneumatic control cylinder; a three-way pneumatic valve disposed between the source of pneumatic pressure and the pneumatic volume of the hydraulic-pneumatic control cylinder; a first hydraulic valve disposed between the hydraulic volume of the hydraulic-pneumatic control cylinder and the hydraulic actuator; a source of hydraulic pressure communicating with the loading pressure volume and the actuating pressure volume of the hydraulic actuator; a second hydraulic valve disposed between the source of hydraulic pressure and the actuating pressure volume of the hydraulic actuator; a hydraulic reservoir communicating with the actuating pressure volume of the hydraulic reservoir; a third hydraulic valve disposed between the source of hydraulic pressure and the hydraulic actuator; and a fourth hydraulic valve disposed between the actuating pressure volume of the hydraulic actuator and the hydraulic reservoir.