Understanding Vacuum Pressure, Absolute Pressure and Compound Pressure

Pressure is the force applied perpendicularly to the surface of an object by squeezing the surface of the object being pressed. This article will introduce the definitions of different types of pressure, vacuum pressure, absolute pressure, and compound pressure, as well as their differences. Choosing pressure sensors of different pressure types will make your pressure measurement accurate and easy.

Vacuum Pressure

We live in an environment full of air. If all the air in the atmosphere is removed, we will get an absolute vacuum. One standard atmospheric pressure is 101325 Pascals (Pa). Vacuum pressure refers to the pressure below one standard atmospheric pressure, also known as negative pressure or vacuum degree. Vacuum pressure can be used in the semiconductor field, vacuum packaging, scientific research and industrial production.

Absolute Pressure

Absolute pressure is the pressure value relative to the vacuum degree of 0. Suppose we are in a container full of air, and slowly remove the air in the container. When there is no air in the container, we get an absolute vacuum. Then the absolute pressure value can be calculated by adding the gauge pressure to the local atmospheric pressure value. For example, in an environment of 100Kpa, the gauge pressure in a container is 70Kpa, then the absolute pressure of the container is 100Kpa+70Kpa=170Kpa.

Compound Pressure

Compound pressure refers to the situation where both positive and negative pressure can be measured. A compound pressure sensor or pressure gauge can monitor both types of pressure. Such a product is the most suitable product if the pressure changes above or below 0. For example, the pressure monitoring of an air compressor requires measuring the positive pressure of the refrigerant and the negative pressure of the evacuation or leak test.

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