3.4: Operation and Schematic Symbol of a Pressure Gage

Operation of a Bourdon Tube Pressure Gauge in Hydraulic Systems

The most widely used type of hydraulic pressure gauge is the Bourdon tube gauge. Its operation is based on the principle of mechanical deformation.

At its core, a Bourdon tube gauge contains a curved, hollow tube that behaves similarly to a party horn that unrolls when air is blown through it. As hydraulic fluid enters the gauge, increasing pressure causes the tube to straighten slightly. This motion is transferred through a mechanical linkage, moving a pointer on the gauge face to indicate pressure. The higher the fluid pressure, the more the tube straightens, resulting in a greater pointer movement.