There are two types of pressure gauges for hydraulic applications:
Comparison of the two gauges
| Gauges | Bourdon tube type | Diaphragm type |
| Application | Most commonly used | (1) Applications where it is necessary that to-be-measured fluid should not mix or contact the working parts of the gauge past the diaphragm; (2) Low pressures measuring applications |
| Contamination | Sealed; less contamination risk from fluid (to be measured) | |
| Measurement range | Pressure range of bourdon tube gauges varies from 0 – 0.6 bar (0 – 8.7 psi) to 0 – 1600 bar (0 – 23206 psi) with an accuracy class of typically between 0.1 and 4.0. | 0 – 2.5 mbar (0 – 0.036 psi) and 0 – 25 bar (362.5 psi), with an accuracy class of typically between 0.6 and 2.5 |
NOTE: Accuracy classes (KL) determine the maximum margin of error each pressure gauge is allowed to have in terms of the percentage of the maximum scale reading. For example, a pressure gauge with a maximum reading of 10 bar and accuracy class 4 may deviate from the actual pressure by 4% ( 0.4 bar).
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