When testing a safety valve by hand, the pressure on the boiler should be at least _______% of the safety valve set pressure?

When testing a safety valve by hand, it is important that the pressure on the boiler is at least 75% of the safety valve set pressure to ensure the valve operates correctly and can be tested accurately. This pressure level allows for adequate force to be applied to the valve, which simulates realistic operating conditions. Testing at this percentage helps to confirm that the valve will open at its designated set pressure during actual service.

Testing the valve with insufficient pressure might not provide an accurate reading of its performance, as the valve may not fully function or could remain seated due to inadequate pressure, leading to ineffective verification of its operation. Therefore, maintaining a testing pressure of at least 75% ensures that the safety valve is not only functional but also reliable in preventing overpressure situations in the boiler system.