What is the minimum pressure for testing a safety valve by hand?

The minimum pressure for testing a safety valve by hand should be set at 75% of the popping pressure. This is because testing at this level ensures that the safety valve operates correctly and can effectively relieve pressure as intended. By using 75% of the popping pressure, it is possible to verify that the valve will properly function under conditions that closely simulate the operational pressures it will encounter. Testing at this level helps to confirm that the safety valve will open and close reliably within the proper range, thus ensuring safety in the operation of the system it protects.

Additionally, testing at lower percentages may not provide a sufficient indication of the valve's functionality or reliability, which is critical for maintaining safe operating conditions in any system that relies on pressure regulation and safety.