Manometer

A manometer may be any device that measures pressure. However, unless otherwise qualified, the term “manometer” most often refers specifically to a U-shaped tube partly filled with fluid. You can easily build this type of manometer as part of a laboratory experiment to demonstrate the effect of air pressure on a liquid column.

A simple manometer can be built by partially filling a clear plastic tube with a colored liquid to allow the fluid level to be easily observed. The tube is then bent into a U-shape and fixed in an upright position. The levels of the fluid in the two vertical columns should be equal at this point, as they are currently exposed to the same pressure. This level is therefore marked and identified as the zero point of the manometer.

The manometer is placed against a measured scale to allow any difference in the height of the two columns. This height differential can be used directly to make relative comparisons between different test pressures. This type of manometer can also be used to calculate the absolute pressure when the density of the liquid in the manometer is known.