Instrumentation for pressure measurements may be classified regarding to the operational principle used or type of pressure to be measured.
If we consider operational principles employed, then process instrumentation for pressure measurements may be categorised as follows:
• liquid filled pressure instrumentation: “U”-tube manometers, well manometers, bell-type manometers, liquid barometer, absolute pressure manometer;
• elastic-element mechanical pressure gages: Bourdon tube pressure gages, bellows-type pressure gages, diaphragm-type pressure gages;
• dead-weight pressure gages;
• electrical-type pressure gages: piezoelectric pressure gages, capacitance pressure gages, strain-type pressure gages.
Here is the classification of instrumentation for pressure measurements with respect to the type of the measured pressure:
• pressure gages, for measurements of pressures above atmospheric pressure;
• vacuum pressure gages, for measurements of pressures below atmospheric pressure;
• vacuum manometers, for measurements of both pressures above and below atmospheric pressure;
• barometers, for measurement of atmospheric pressure;
• differential pressure and vacuum gages, for measurements of difference of pressures.