
A pressure comparator is a convenient instrument for bench pressure calibration. You would perform a bench calibration to maintain reference conditions and to get the lowest possible uncertainties. The bench is also a convenient place to inspect, adjust, and repair the devices under test.
To perform a test on a pressure gauge using a pressure comparator and a reference gauge, follow these steps:
- Mount the pressure gauge in the same orientation (vertical or horizontal) as it is normally used in the process. Use an angle adapter to adjust the angle if necessary.
- Mount the reference gauge so that you can see the display easily.
- If you are using a hydraulic comparator, prime the fluid with the priming pump to remove any bubbles.
- Measurement points should be distributed uniformly over the calibration range. Use a manual pump to source pressure conveniently up to 300 psi; above that use an external pressure supply.
- For gas comparators, use the fine needle valve or fine adjustment screw press to precisely meter the pressure.
- With hydraulic models, use the screw press to source and find adjust the pressure.
- You may adjust the source pressure until the device under test is reading a nominal pressure or until the reference gauge reads the nominal pressure.