Polyhydron Modular Pilot Operated Check Valve Supplier In Coimbatore Modular Pilot Operated Check Valve. These Valves are available with the pilot operated check valve facility on either A or B or both A and B ports. The hydraulic opening operation for free flow in reverse direction is achieved by means of internal pilot pressure available from the other working port. To ensure proper closure of both valve poppets, both user connections should be unloaded when the control valve is in the neutral position by connecting with the return line