The pressure of a liquid may be measured by the manometers. These are the devices used for measuring the pressure at a point in a liquid by balancing the column of the liquid by the same or another column of liquid. The manometers are classified as follows:
1. Simple manometers such as piezometer and U-tube manometer.
2. Differential manometer.
A piezometer is the simplest form of manometers used for measuring moderate pressures of liquids.
A manometer is used to measure
1. High pressure of liquids,
2. Vacuum pressures, and
3. Pressure in pipes and channels.
A differential manometer is used to measure difference of pressures between two points in a pipe.