Pressure

What is pressure? The definition of Pressure

In a fluid system, pressure means the force acting upon and normal to unit area of the system.

What is the definition of Absolute Pressure?

An absolute pressure refers to the absolute force acting normally on unit area of the fluid system. It is of interest to note that whilst absolute pressure is always positive for a gas, some rare cases of negative absolute pressure have been found for some liquids.

What is Gauge pressure?

Gauge pressure represents the difference between the absolute pressure and the local barometric pressure. Very often, in practice, the readings obtained from pressure gauges are relative to the barometric pressure. It is important that the distinction is clearly understood as serious errors in results can sometimes be traced to this point.

What is Vacuum?

Vacuum is the amount by which the barometric pressure exceeds the absolute pressure (Le. it is then a negative gauge pressure).

Pressure Measurement

The liquid filled manometer is a popular instrument for pressure measurement of steady fluid pressures because of its extreme simplicity and reliability. Many versions of the manometer principle are in use.

Click here to read about Manometers and U Tube Manometer.

Click here to read about Bourdon Tube for pressure measurement.

Pressure Gauge in science experiments