How Pressure is measured??
MEASUREMENT OF PRESSURE
The pressure of a fluid can be measured in two ways:
1. Manometers 2. Mechanical gauges
Manometers are defined as the devices used for measuring the pressure at a point in afluid by balancing the column of fluid by the same or another column of the fluid. Theyare classified as
a) Simple manometers
Piezometer, U-tube manometer, single column manometer
b) Differential manometers
U-tube differential manometer & Inverted U-tube differential manometer
Mechanical gauges are defined as the devices used for measuring the pressure bybalancing the fluid column by spring or dead weight. The commonly used mechanicalgauges are
a) Diaphragm pressure gauge c) Dead weight pressure gauge
b) Bourdon tube pressure gauge d) Bellows pressure gauge
The relationship between pressure and head is utilized for pressure measurement in the
manometer or liquid gauge. The simplest form is the pressure tube or piezometer, consisting
of a single vertical tube, open at the top, inserted into a pipe or vessel containing liquid
under pressure which rises in the tube to a height depending on the pressure. If the top of
the tube is open to the atmosphere, the pressure measured is gauge pressure.
Problems with the Piezometer:
1. Can only be used for liquids
2. Pressure must above atmospheric
3. Liquid height must be convenient i.e. not be too small or too large.