An open-close test is a functional test for in-tank valves used as drain valves.
In Pressure/vacuum relief valve Pressure/vacuum relief valve is an umbrella term that includes pressure or vacuum relief valve as well as pressure and vacuum relief valve. this case, their operating position is NC (normally closed). In this test, the in-tank valve In-tank valve An in-tank valve is located inside a storage tank and is open under normal working conditions. is opened once and closed again.