Absolute Pressure

Absolute pressure is a type of pressure measurement that is relative to the zero pressure in the empty, air-free space of the universe, also known as an ideal or absolute vacuum. It is denoted with the subscript "abs" (Pabs) and is measured relative to a full vacuum, with a reading of 0 PSIA. Absolute pressure is not influenced by environmental factors such as weather or altitude, making it a precise and definite measurement.

In contrast, gauge pressure is defined as the difference between an absolute pressure and the prevailing atmospheric pressure. It is denoted with the subscript "e" (Pe) and is calculated as the difference between absolute pressure and atmospheric pressure (Pabs - Pamb) . Gauge pressure is measured relative to atmospheric pressure and can be affected by changes in weather and altitude.

The choice between absolute and gauge pressure measurement depends on the specific application and the need for precision. Absolute pressure is suitable for applications where pressure measurements should not be influenced by changes in atmospheric pressure, such as in the storage and delivery of toxic gases or leak testing sealed containers. On the other hand, gauge pressure is commonly used in applications where the measurement is relative to atmospheric pressure, such as in many industrial and mechanical systems.

In summary, absolute pressure is measured relative to a full vacuum and is not affected by environmental factors, while gauge pressure is measured relative to atmospheric pressure and can be influenced by changes in weather and altitude. The choice between the two measurements depends on the specific requirements of the application.

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