Procedure for a leakage test of PSV using water.
The test medium is water at ambient temperature, which is allowed to stabilize without visible flow. The inlet pressure is then increased to the test pressure, and the valve is mounted vertically on a water test stand. The test pressure is set at 90 percent of the set pressure for valves with a set pressure greater than 50 pounds per square inch gauge (345 kilopascals gauge). For valves with a nominal pipe size of 1 inch or larger, the leakage rate is limited to 10 cubic centimeters per hour per inch of nominal inlet size. For soft-seated valves, there is no leakage for 1 minute.