The Petro Controls “HC3” interface is a 3-way, normally closed, pilot operated, automatic hydraulic controller. It is normally installed in a control panel. It receives instrument pressure 50-150Psi from a safety system component such as a master relay and hydraulic supply pressure till 10.000 PSI from a pump.
During normal operation, instrument pressure holds the controller in the open position. The supply pressure passes through the outlet, and the hydraulic system will maintain its required working pressure.
When the master relay is actuated, it will bleed instrument pressure from the controller and the spring will push the controller into the closed position. The supply pressure becomes blocked, and than the outlet is exhausted, and returned to the reservoir.