A manometer may be any device that measures pressure. The term "manometer" usually refers to a basic liquid column instrument, unless otherwise specified. However, there many specific types of manometers with more specific names, such as a piston gauge, McLeod gauge, aneroid gauge and Bourdon gauge.
Use a liquid column manometer for demonstration purposes. Fill a tube halfway with coloured water and bend it into a U-shape. Connect one end to a source of pressure and leave the other end open to the air. The height differential will indicate the pressure differential between the two halves of the tube.
Measure pressure with a piston gauge. These types of gauges use a solid spring or weight to counterbalance a fluid's pressure. These types of manometers are commonly used to measure the pressure in a tire.
Employ a McLeod gauge for applications where the gas doesn't produce condensation when it's compressed. This type of gauge compresses a sample of gas down to a few millimetres. A McLeod gauge is not suitable for continual monitoring.
Make an aneroid gauge to measure pressure without a fluid. These instruments use a metal strip that flexes in response to a pressure differential. These gauges are not restricted to a particular fluid and are less likely to contaminate the system.
Monitor the pressure in an enclosed container with a Bourdon gauge. This device uses a coiled tube that expands in response to a pressure increase. The tube is connected to an arm which rotates to indicate a pressure reading. Bourdon gauges were commonly used in steam locomotives.