• 17 Feb 2022

What is the Difference Between Absolute, Gauge, Differential, Atmospheric and Vacuum Pressures?

Determining pressure is an imperative part of many industries, from scientific research to medical and manufacturing applications. Obtaining accurate, useful data helps with quality control, consistency and decontamination processes. When it comes to measuring pressure, there are a few ways to determine a correct reading and apply them in a meaningful way. But what is the difference between the types of pressure, and why does it matter?

What is pressure?

Pressure can be described as the amount of force applied to an area. However, there are many types of pressure with significant differences that affect the use and measurement. In many cases, choosing the type of pressure is just as important as choosing your pressure range. Let’s take a look at some of the types of pressure and how they can be applied.

Absolute pressure

Absolute pressure is the pressure of having no matter inside a space. It is the sum of gauge and atmospheric pressure. This pressure can be measured with an electronic diaphragm sensor, which determines the difference between a permanently sealed vacuum and the open area on the other side.

The most common applications for absolute pressure sensors are related to the weather. In particular, absolute pressure is effective at measuring barometric variations as a result of changes in high and low atmospheric pressure systems caused by fluctuating weather patterns. Absolute pressure is also used to determine changes in ambient pressure when elevation is applied.

Gauge pressure

Gauge pressure is typically measured against ambient atmospheric pressure and can be used to determine weather changes and barometric variations. Gauge pressure sensors can return a positive or negative result, depending on their set pressure frame. If the sensor is higher than ambient pressure, it is known as positive pressure; if the gauge pressure is lower, it is known as negative or vacuum pressure.

Atmospheric pressure

Atmospheric pressure is the pressure caused by the Earth’s atmosphere. Commonly affected by altitude, temperature and wind velocity, atmospheric pressure differs depending on where you are taking your measurement from. Typically, pressure gauges at sea level will read zero at atmospheric pressure – however, underwater gauges will increase with every 10 metres descended beneath the surface.

Differential Pressure

Differential pressure is the difference between two pressures. This pressure measurement can be either positive or negative, depending on how and why the pressures are taken. Typically, it is determined by exposing a diaphragm sensor with two independent connector points to varying pressures on either side of the apparatus. Differential pressure is often measured as the difference between atmospheric pressure and secondary pressure to prevent air mingling between areas.

Differential pressure is essential for cleaning and maintaining control rooms, particularly in medical applications. By ensuring that the control room is kept at a positive ambient pressure, maintainers can prevent an influx of airborne particles that would contaminate samples and clean rooms.

Vacuum pressure

A perfect vacuum pressure is defined as zero pressure where there is no matter or air inside of a sealed space. It is typically measured relative to ambient atmospheric pressure. Because of its unaffected state, vacuum pressure is often used as a fixed reference for measuring other types of pressure, particularly absolute pressure.

Choose accurate pressure measurements with NWI Group

No matter your pressure measurement needs, NWI Group has the equipment for you. Accurate, reliable and stable, our sensors have been applied in various industries for over 30 years and continue to set the standard for pressure measurement equipment. With this accumulation of experience, our experts can help select the correct apparatus for your operation and help install and maintain the equipment to ensure that you get the results you need. Contact us today to find out more about how our sensors are right for you.