At HEROSE, the sealing of safety valves is tested according to the following procedure:
The outlet is closed with a plug, which is connected to a hose. This hose ends 10 mm below the surface level of the water in a water glass. The internal diameter of the hose is approx. 5 mm. Any leakage from the valve is made visible by bubbles of the medium in the water. (See API 527)

The valves must not release bubbles up to 95% of the set pressure.