A complete safety valve test and calibration includes three types of test items: safety valve popping test, safety valve reseating test and safety valve sealing test.
The Purpose of Safety Valve Popping Test
The safety valve pop test, also known as safety valve setting pressure test, aims to verify whether the safety valve can pop up in a timely manner under the setting pressure and perform its protective function. By simulating overpressure conditions, it confirms that the safety valve can accurately open and release excessive pressure under the setting pressure, preventing equipment damage due to overpressure.
Safety Valve Popping Test Procedures
The safety valve pop test consists of four procedures as following.
1. First of all, place your safety valve on PSV test bench and clamp it firmly. In this way, the sealing disk or threaded adapter that comes with the PSV test bench will tightly block the inlet of the safety valve.
2. Pressurize safety valve in stages. That is, inject the testing medium into the safety valve and pressurize the medium to 90% of the PSV setting pressure, then slowly pressurize the medium until the safety valve pops.
3. Record safety valve popping pressure. If you are using a manual safety valve testing equipment, you need to visually observe the pressure gauge reading to record PSV popping pressure value. For automatic safety valve test bench, it will automatically record the PSV popping pressure value.
4. Compare the safety popping pressure value with its setting pressure value. If the deviation is within the allowable range, the safety valve is qualified; otherwise, it is unqualified.
To eliminate the error of a single test, it is recommended to test the safety valve three or more times and take the average of the test data to determine whether PSV popping test is qualified.
Safety Valve Reseating Test
The safety valve reseating test is performed consecutively after PSV popping test. And it aims to verify whether the safety valve can reset timely after popping and overpressure relief, and whether the reseating pressure meets design requirements.
The safety valve reseating test procedure is as follows: The safety valve will continuously release excess pressure after the safety valve pops. When the pressure drops to a certain level, the safety valve will automatically close, this action is called safety valve reseating. Record the pressure value at this point, which is the safety valve reseating pressure. If the reseating pressure of the safety valve is within the design range, the safety valve is qualified. Conversely, if the reseating pressure of the safety valve is too low or it fails to reseat, it is unqualified.
Safety Valve Popping Pressure, Setting Pressure and Reseating pressure
During the safety valve testing and calibration, it is essential to figure out the differences and relationships between the safety valve setting pressure, popping pressure and reseating pressure.
Safety valve setting pressure is the preset pressure at which the safety valve should pop, and it is a pressure value that has been calibrated in advance.
Safety valve popping pressure is the critical pressure value at which the safety valve begins to release excessive pressure. Ideally, PSV popping pressure should be equal to PSV setting pressure. But in practice, PSV popping pressure is usually slightly higher than PSV setting pressure.
Safety valve reseating pressure is the pressure at which the safety valve closes again after popping and overpressure relief. The PSV reseating pressure is usually lower than PSV setting pressure.
Safety valve popping test, reseating test and sealing test are usually conducted consecutively. To facilitate users to test and calibrate various safety valves, we provide manual and automatic safety valve testing equipment for users to choose from. Please contact us for brochures.
