Electronic pressure gauges
These employ a pressure transducer connected to a resistance bridge, followed by an amplifier. Pressure may be indicated by a meter or a digital readout. The pressure range of this type can be as high as required. The accuracy depends on the quality of the transducer element and compares favourably with the Bourdon tube. It is normally within _+1% of the full scale reading, but can be much more accurate.
A portable instrument which can be used for checking the operation and settings of valves and switches is shown in Figure 4. This particular instrument has an accuracy of _+0.2% of full scale reading and a pressure range up to 199.9 lb/in 2 (14 bar). It can readily be set to give readings in other units such as heights of water or mercury.