Digital manometer is measuring pressure and its variations across two points that are a part of the same system-this is known as differential pressure.
Differential pressure is of great importance to weather forecasters, among others.
The digital manometer is also used at homes to monitor propane driven appliances such as barbeque grills, maintain and detect faults in air conditioning systems and detect gas leaks very quickly. Manometric measurement is the subject of pressure head calculations. The most common choices for a manometer’s fluid are mercury (Hg) and water; water is nontoxic and readily available, while mercury’s density allows for a shorter column (and so a smaller manometer) to measure a given pressure.
Hydrostatic gauges (such as the mercury column manometer) compare pressure to the hydrostatic force per unit area at the base of a column of fluid. Hydrostatic gauge measurements are independent of the type of gas being measured, and can be designed to have a very linear calibration. They have poor dynamic response.
A manometer is a good example, as it uses the surface area and weight of a column of liquid to both measure and indicate pressure. Likewise, the widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge.