Cyclical pressure testing apparatus

Abstract

A pressure testing apparatus including a twin cylinder accumulator assembly having a first cylinder and a first piston dividing the first cylinder into first and second chambers. The first chamber communicates with a test specimen and contains a first fluid. The twin cylinder accumulator assembly also includes a second cylinder coaxial with the first cylinder and a second piston which divides the second cylinder into third and fourth chambers and which is connected to the first piston by a common piston rod. The fourth chamber communicates with a hydraulic pressure unit and is supplied with alternating high and low pressures to cyclically pressurize the first fluid in the fourth chamber and the test specimen communicating therewith. A switch actuator is mounted on the piston rod for actuating first and second proximity sensors to monitor piston rod movement. In the event of a leak in the specimen causing the piston rod to exceed its normal stroke when compressing the fluid in the first chamber, the switch actuator actuates the first proximity sensor to signal a control unit to open a valve to permit make-up fluid to be pumped into the system. The second valve remains open until the piston rod is moved in the reverse direction a distance sufficient to cause the switch actuator to actuate the second proximity sensor to signal the control unit to close the second valve.