Pressure Measurements
Barometer
Piezometer
Open-ended tube connected to a vessel / pipe containing a liquid.
Measures the pressure head of a liquid.
Advantages
- Simple
- Small pressure differences can be measured
Disadvantages
- Only for liquids
- Long tube required to measure even moderate pressures
Manometer
Hydrostatic principle is used here. Measures absolute pressue. Manometer liquid should not mix with the liquid in which the pressure is to be measured.
If
Differential Manometer
Used to measure pressure difference between two points. Can be used for both liquids and gases. Difficult to measure small pressure differences (because small displacement of manometer liquid).
Pressure Gauges
Bourdon Pressure Gauge
Advantages
- Easy to use
- Wide range of pressures can be measured
Disadvantages
- Not very accurate
- Needs to be calibrated regularly