In manometer devices, pressure difference between manometric liquid and measuring liquid is obtained and it is equated to relation hϱg, ϱ is the mass density of the manometric liquid.

Thin plate diaphragms can be used for measuring both static and dynamic pressures. But the limitation is that the frequency of application should be small.

Bellows can be used for measuring Absolute pressure, Gauge pressure and Differential pressure of measuring medium. This is accomplished using two bellow chambers provided.

Both water and transformer oils are used in small pressure differential applications, but the difference is that water has problems related to relatively faster evaporation.

Capsules are made by enclosing two identical corrugated diaphragms forming a closed chamber.

In bourdon tubes converts input pressure into displacement and displacement of the needle will be directly proportional to input pressure.

R is the radius of membrane and S is the radial tension in N/m. Displacement will be an indication of applied pressure.

In bellows pressure to force conversion takes place, which is acted on bellows and can be measured for calculating applied pressure.

Both diaphragm and capsule convert pressure into displacement which can be measured using indicating instruments. Displacement will be proportional to applied pressure.

Primary transducers are devices which converts measurand into mechanical quantities. Diaphragm converts pressure into displacement which is a mechanical quantity.