How and why to use a pressure comparator for bench calibration

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.
 

1. 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.
2. Mount the reference gauge so that you can see the display easily.
3. If you are using a hydraulic comparator, prime the fluid with the priming pump to remove any bubbles.
4. 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.
5. For gas comparators, use the fine needle valve or fine adjustment screw press to precisely meter the pressure.
6. With hydraulic models, use the screw press to source and find adjust the pressure.
7. 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.

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