- April 19, 2023
- Posted by: admin
- Category: Compliance Service, PSV Calibration Mechanical
PSV Calibration: One of the simple yet significant instruments used for safety is pressure safety valves. However, some might wonder what a pressure safety valve is. As the name suggests, it’s used for protecting the pressure vessels from intense pressure which can result in a pop action or rapid opening after reaching the standard pressure. The PSVs are commonly found in gas industries wherein they are installed in permanent tanks.
It is easy to use but significant from the viewpoint of safety. It is powered by fluid pressure and doesn’t use electrical power. Thus, it is the last line of safety when other devices fail. The purpose of PSV is to open and release the pressure when it reaches the set pressure. It gets closed again after the pressure is normalized.
Reason to Calibrate a PSV
Every pressure safety valve comes with a specific set of pressure engraved on the body. It is a pressure that is required for verifying that the valve will stand true to its function whenever required.
Here’s a look at some reasons for performing mechanical PSV calibration and testing:
- To make sure that it’s within the set pressure.
- As a preventative measure to ensure that PSV works in a proper condition.
- PSV is a mechanical component. It has a spring which offers the set pressure. If one of these parts gets damaged, it can impact the pressure.
- The closing or resealing of the PSV can get affected due to exposure to contaminants such as debris and dust. This can lead to a leak.
- If the PV disc stays inactivated or closed for a long time, it can get stuck up affecting the pressure.
The testing and certification for the PSV can be done by a reputed NABL lab near me. It ensures that they are functional and safe for usage.
What Happens During PSV Calibration Process
The PSV calibration is performed by comparing the set pressure with the displayed value of the standard.
- Decide the set point of the pressure. It is important to be aware of the set point to gauge the opening of the valve when controlling the source of pressure.
- Once the set-up has been done, make sure that there is no leakage.
- The pressure is increased till there is a sudden pop or release action.
- The displayed pressure reading is recorded in the measurement datasheet.
- Gradually the pressure flow is decreased and the closing of the valve is observed. The reseating pressure value is recorded.
- The procedure is repeated 2-3 times.
- The PSV is labelled and sealed for preventing any unauthorized changes.
Stages to Observe During Calibration
- Set Pressure
It is the pressure reading when the valve pops up or rapidly releases. The tolerance is generally 3% of the set pressure.
It is set above the set pressure when the valve opens completely. The tolerance is generally 10% above the set pressure.
- Closing Pressure
This is the reseating pressure which is the pressure reading when the valve closes fully and stops releasing.
PSV is a mechanical item and it can be repaired and adjusted easily. Three steps to perform adjustments:
- Remove the bonnet cover. You will see a ring with a screw.
- Now loosen up the ring-like screw to access the adjusting screw.
- After the lock gets loosened, turn the screw either clockwise or counter-clockwise. Rotate the screw till the desired range gets adjusted.
- Don’t over-rotate as it might damage the spring.
The pressure safety valve is the last line of defense for the pressured vessels from over pressure. The above mentioned information talked about the pressure safety valve, how the calibration is done, and the three stages of observation during the calibration. You must hire a reliable PESO approved agency which is also NABL accredited lab in Vadodara for performing the safety valve testing for assurance of quality.the calibration of PSV, PVRV and EFV.