In the world of compressed air and pneumatics, a lot revolves around control. Therefore, the question of how does a pressure gauge work is very logical for many technical buyers, mechanics and machine builders. At Pneuparts, we see that a pressure gauge often seems small, but in practice it plays a major role in monitoring pressure, safety and process stability. If you want to measure pressure in a system properly, you also want to understand what a pressure gauge does, which version fits and what you should pay attention to when choosing.

A pressure gauge is a measuring instrument that allows you to measure the pressure of both gases (such as compressed air or gas) and liquids (such as water or oil). That sounds simple, but the operation of a pressure gauge differs per type. Moreover, the application often determines which instrument is most suitable. Think of compressed air, water pressure, vacuum, chemical media or viscous media. In this article, we explain step by step what you can measure with a pressure gauge, how the pressure gauge works and which version suits your situation.

How does a pressure gauge work in the base?

The brief explanation of how does a pressure gauge work is as follows: a pressure gauge measures the pressure of a gas or liquid relative to a reference. This is often the atmospheric pressure, but you can also measure absolute pressure or differential pressure. The SI unit of pressure is pascal, although in practice you usually see bar or mbar on the scale or display.

The main principle of operation remains the same. Pressure is applied to a pressure-sensitive element in the instrument. That element deforms, moves or expands. That change is then converted into a readable measurement. With an analogue pressure gauge, you can see this on a dial with a pointer. With digital pressure gauges, the measurement is converted into an electrical signal and then displayed on a digital display.

So a pressure gauge does not just measure a random value. The pressure measurement shows how much force a gas or liquid exerts on a surface. This allows you to monitor a system, identify anomalies and prevent problems such as leakage, wear and tear or incorrect adjustment.

Does a pressure gauge work differently for analogue and digital versions?

Yes, the basis is the same, but the measurement mechanism differs. There are different types of pressure gauges and they are classified based on technique, medium and application. The most commonly used versions are analogue pressure gauges, digital pressure gauges and other mechanical pressure gauges.

Analogue versions usually work with a mechanism that converts movement into a deviation of the pointer. Digital pressure gauges use electronic sensors to measure pressure. As a result, they are often easier to read, especially with small pressure differences or when high precision is desired.

Digital pressure gauges often have additional functions. Think of a digital readout, multiple units, data logging and sometimes an alarm function. This makes them useful in installations where you want to monitor pressure changes or where accurate measurement is important. Nevertheless, analogue versions remain popular, precisely because they are robust, simple and reliable in daily use.

Mechanical pressure gauges and the bourdon pressure gauge

Mechanical pressure gauges are used in numerous industries. The bourdon pressure gauge is the most widely used technology. In many compressed air and process installations, you will come across this type of pressure gauge, because the design is simple and strong.

Do analog pressure gauges always work with a bourdon tube?

Not always. Many analogue pressure gauges work with a bourdon tube, but there are also aneroid pressure gauges and other mechanical versions. In addition, there are capsule elements for low pressure in gaseous media.

So when people ask if analog pressure gauges always work the same way, the answer is no. The main principle of operation is the same, but the measuring element can have different shapes. The choice depends on pressure range, medium, accuracy and application.

Diaphragm pressure gauge: suitable for low pressure and viscous media A diaphragm pressure gauge works with a flexible diaphragm that responds to pressure. This membrane is often circular and clamped between two flanges. As soon as pressure is applied to one side of the membrane, the element deforms. This distortion is converted into a movement of the pointer or into an electrical signal. The diaphragm pressure gauge is suitable for low pressure, small pressure differences and specific applications with contaminated, aggressive or viscous media. This type can also be useful for corrosive liquids, especially if you choose stainless steel or other suitable materials. This type is often used in chemical processes, the beverage industry, medical equipment and installations where purity is desired. Membrane pressure gauges typically measure between 2.5 mbar and 25 bar. This makes them interesting when high sensitivity is important. The diaphragm also separates two environments, making it less likely that the medium can damage the inside of the mechanism. This helps to limit wear, leaks and unreliable behaviour.

Digital pressure gauges: high accuracy and additional functions

Digital pressure gauges are increasingly being used in industries where accurate pressure measurements are needed. This type of pressure gauge measures via sensors. The signal is then converted and displayed on a display. This gives you an easy-to-read measurement, often in bar, mbar, pascal or other units.

An advantage of digital pressure gauges is their high accuracy. Many models also offer additional functions such as minimum and maximum registration, data logging and easier comparison of measured values. In critical applications, for example in medical equipment, aviation, power plants or special process plants, this is often a big plus.

In addition, digital pressure gauges help monitor static pressure, vacuum or overpressure. They are suitable for a wide range of applications where control, accuracy and information are important. However, you do have to take into account power supply, the environment, any vibrations, and the working range of the device.

Different applications for which pressure gauges are used

Pressure gauges are used in many industries and for a variety of applications. Think of compressed air, control of hydraulic systems, heating systems, water pressure in pipes, vacuum technology, automotive applications and mechanical engineering. You can also see different versions in chemical environments, offshore, mining and medical equipment.

A simple pressure gauge can already provide a lot of insight. For example, you can use it to check whether a compressed air system is operating within the correct pressure range. In heating systems, a pressure gauge is used to monitor the water pressure. With tire pressure, you use a compact instrument to quickly measure pressure. In process plants, a pressure gauge helps to detect leaks or pressure changes at an early stage.

The applications in which a pressure gauge adds value are therefore broad. The pressure gauge not only measures pressure, but also supports safety, consistency and control in a system. This allows you to intervene more quickly and prevent bigger problems.

Which pressure gauge do you choose?

Which pressure gauge you need depends on various factors. Choosing the right pressure gauge starts with the application. You look at the medium, the pressure range, the desired accuracy, the connection and the environment.

Important selection criteria for pressure gauges

The main selection criteria are the type of pressure gauge, scale, working range, and materials. For corrosive media, stainless steel is often a logical choice. For general compressed air applications, brass is widely used. For viscous media or media with contamination, a membrane pressure gauge is often better suited than a standard bourdon version.

Also pay attention to the accuracy class. This is usually between 0.1 percent and 4 percent. A pressure gauge with 10 bar and class 4 may therefore deviate by 0.4 bar. For critical processes, you therefore often want a more accurate instrument. Furthermore, pressure gauges usually function best between 25 and 75 percent of their scale range. This promotes reliable measurement and a longer lifespan.

Safety Precautions and Maintenance

Good use does not stop with the purchase. Safety measures remain important, especially in the case of high pressure, flammable substances or oxygen. Blowout protection can help to limit risks if an element were to crack. Liquid-filled models, for example filled with glycerin, help absorb vibrations and often extend the lifespan.

In addition, periodic calibration is important. Regular calibration prevents the build-up of measurement errors and is crucial for accurate measurements in critical applications. Regular checking for leaks, damage to the dial, a worn connection or an abnormal measurement also helps to prevent problems. Well-maintained measuring instruments remain more reliable and safer to use.

Practical summary for your installation

If you want to understand what you measure with a pressure gauge, the answer is clear: you measure the pressure of a gas or liquid in a system. But the right choice requires more. You need to know what medium you are measuring, how much accuracy is needed, what conditions apply and which type fits best.

For general industrial applications, a bourdon pressure gauge is often a robust choice. For low pressure, contaminated media or viscous media, a membrane pressure gauge fits better. If you want high precision, digital readout and extra functions, digital pressure gauges are interesting. This way you make a choice that is not only technically correct, but also helps to keep your process running reliably.

At Pneuparts you will find a wide range of pressure gauges and other components for compressed air and pneumatics. You can count on specialist advice and technical support if you want to determine which pressure gauge is suitable for your system.

This way you keep a grip on pressure and choice

A pressure gauge may seem like a small product, but in practice it is an important tool for pressure measurement, control and safety. You now know how a pressure gauge works, which techniques are used most often and why the type of pressure gauge matters a lot for the measurement. You can also see that material, accuracy, calibration and medium have a direct impact on performance and lifespan.

If you want to replace a pressure gauge or build a new installation, it pays to look further than just the range in bar. Look at application, medium and desired reading. For a stable installation, the right components around the measurement also play a role, such as control, measuring and filtering, a suitable air piping system, reliable hose and pipe connectors, suitable push-in couplings and fittings and the right compressors, dryers, boilers and parts. In addition, check out our technical articles on push-in couplings, which coupling you need and the operation of pneumatic valves if you want to optimize your compressed air installation more broadly.

Frequently Asked Questions (FAQ) What do you measure with a pressure gauge? With a pressure gauge you measure the pressure of a gas or liquid in a system. This can be relative pressure, absolute pressure, overpressure or vacuum. In practice, you use a pressure gauge for compressed air, water pressure, hydraulics or heating systems, for example. The measured value is often displayed in bar, mbar or pascal. What is the difference between an analogue and digital pressure gauge? An analog pressure gauge shows the pressure via a hand and dial. A digital pressure gauge uses sensors and shows the value on a display. Digital pressure gauges are often more accurate to read and sometimes have additional features, such as data logging or multiple units. Analogue models are robust and easy to use. When do you choose a diaphragm pressure gauge? A diaphragm pressure gauge is often chosen for low pressure, contaminated media, viscous media or corrosive liquids. The diaphragm separates the medium from the measuring mechanism, keeping the inside better protected. This type is widely used in chemical applications, process plants and situations where sensitive and reliable measurement is required. How accurate is a pressure gauge? The accuracy depends on the type and class. Many pressure gauges have an accuracy class between 0.1 percent and 4 percent. A model with 10 bar and class 4 may therefore deviate by 0.4 bar. For critical applications, it is smart to choose a more accurate model and perform regular calibration. How do you know which pressure gauge is suitable? You determine this based on medium, pressure range, connection, environment and desired accuracy. For compressed air, a standard bourdon pressure gauge is often sufficient, while for aggressive or viscous media, a diaphragm version may be a better fit. Also pay attention to material, scale and vibrations. If you are in doubt, technical advice will help you make the right choice.

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