The HSPC cartridge type check valve allows free flow in one direction but prevents flow in the other until sufficient pressure is applied at the pilot port.

Pressure at port 2 forces the check ball off the seat and compresses the spring to allow flow to port 1. Reverse flow pressure (from port 1) forces the ball against the seat to stop flow. However, when sufficient pressure is piloted to port 3, it will shift the larger area spool and in turn move the ball off its seat to allow reverse flow from port 1 to port 2.

Pilot pressure must be sufficient to overcome the force generated by the pressure at port 1 and the spring.

The valve is constructed of steel parts, all operating parts are hardened. The cartridge is designed for easy service or field repair.