Understanding Capsule Pressure Gauges: Applications and Advantages

by Mariam Nazir blogger

The devices known as pressure gauges are used to measure pressure. Concerning atmospheric pressure, the gauge pressure is the level of pressure. Positive gauge pressure reflects pressures higher than atmospheric pressure. Gauge pressure is negative, while the pressure is below atmospheric pressure. Other names for the pressure gauge are vacuum gauges or pressure meters. Manometers measure and display pressure based on a liquid column's weight and surface area.

Gauges typically use the zero point for calculating pressure concerning atmospheric pressure. This type of measurement is hence called gauge pressure.

Types of Pressure Gauge

Most popular pressure gauges are developed based on their intended use and function, whether commercial or industrial. Here are a few of the pressure gauges:

  1. Bourdon Tube Pressure Gauge

  2. Diaphragm Pressure Gauge

  3. Capsule Pressure Gauge

  4. Absolute Pressure Gauge

  5. Differential Pressure Gauge

  6. Bellows Pressure Gauge

  7. Manometer Pressure Gauge

  8. Piezometer Pressure Gauge

What is a capsule pressure gauge?

Capsule Pressure Gauges are specifically designed to cope with low-pressure signals. Low-pressure readings are complex for a classic Bourdon Tube-style pressure gauge. They are inaccurate because the low pressure does not distort the Bourdon Tube sufficiently to generate a task.

Capsule pressure gauges, commonly called low-pressure gauges, work through a welded capsule containing two thin diaphragms. While one diaphragm records the pressure signal, the other serves as a reference. After that, mechanical linkages convert the capsule's relative deflection into a rotating movement, which moves the pointer around the gauge's dial.

Capsule pressure gauges meet EN 837-1's Accuracy Classes 1.6 and 2.5 and are highly accurate pressure measuring instruments. They have dial sizes of 100mm and 150mm and are offered in stainless steel. There are several pressure ranges available from 0 to 600 mBar.

Advantages of a Capsule Pressure Gauge?

  • Low range with high accuracy. 

  • All SS internals. 

  • Accuracy ? 1% FSD. 

  • The compact design avoids the use of bulky manometers. 

  • Ingress protection class IP-68. 

  • Low-pressure measurements are a good fit for these pressure gauges. 

Shallow pressures as low as 16 mbar can be measured with capsule pressure gauges. A sensitive element constructed from two diaphragms welded to form a capsule is housed in the casing.


  1. Pressure measurement at shallow pressures

  2. For gaseous, aggressive media, also in aggressive environments

  3. Reliable design, IP54 ingress protection, and outdoor use

Special Features

  1. Up to 50 times the full-scale value of high overload safety

  2. The scale ranges from 0 to 2.5 mbar

  3. The measuring chamber protected against unauthorized intervention

  4. Lowest measurement error and the impact of medium pollution on performance

Applications with capsules

A capsule's pressure chamber cannot be used for liquids because it is not self-draining. For this reason, the only application for capsules is gas pressure measurement. The capsule's sensitivity and its diaphragm's capacity to sense low pressures guarantee that capsules are the best sensors to employ in barometers.

Capsules can be stacked on top of one another to increase sensitivity and deflection. A barometer often has two to five capsules piled on top of one another, depending on how well-made the instrument is.

Because the outside pressure only fluctuates between 920 and 1050 mbar, many capsules are needed. The stacked capsules can drive the pointer since there is a tiny variation between the lowest and maximum air pressure.

Every capsule is sealed hermetically and removed. The exterior of the capsules is subject to atmospheric pressure. A spring is fastened to the top center of the capsule and secured on a bridge to keep the capsules from collapsing as the force builds.

Capsule pressure gauge measurement range

Capsule pressure gauges have accuracy classes of 0.1 to 2.5 and can measure shallow positive and negative pressures between 0 and 0.5 mbar and 0-1000 mbar. They can measure differential pressure as well as absolute and relative pressure.

Absolute Pressure Sensors

The pressure chamber of the capsule is evacuated and sealed hermetically in absolute pressure sensors. A sealed container keeps the capsule in place. The process pressure is then provided to the capsule's outside and injected into the sealed housing via a process connection.


We will measure absolute pressure since the process pressure within the capsule is comparable to a near-perfect vacuum.

Virtually frictionless bellows convey the link connected to the capsule through the housing's wall and towards the indication. The bellows make sure that there is no leakage of housing pressure along the link. In the event of overpressure, the capsules are made to bottom on one another to avoid harm.

Relative Pressure Sensors

The process pressure is applied to the inside of the capsule to measure relative forces. As a result, the process pressure is injected into the capsule by a diaphragm centered around a process connection.

The atmospheric pressure, or reference pressure, is located outside the capsule.

One or more capsules can be used to measure the relative pressure.


Capsule pressure gauges are like super-smart tools that help us measure pressure, especially when it's shallow. They're like the superheroes of pressure measurement. They have this excellent design with two thin diaphragms in a tiny capsule, making them super accurate. Now, these capsules are like little detectives. They can't measure liquids, only gases. But when it comes to sensing low pressures, they are the champions. So, next time you hear about capsule pressure gauges, remember they are excellent gadgets that help us understand pressure super accurately and reliably.


Can Capsule Pressure Gauges measure absolute pressure? 

Yes, Capsule Pressure Gauges can measure absolute pressure by evacuating the pressure chamber and sealing it hermetically, creating conditions similar to a near-perfect vacuum.

How do Relative Pressure Sensors Work in Capsule Pressure Gauges? 

Relative Pressure Sensors apply the process pressure to the inside of the capsule, measuring close forces. The atmospheric pressure, or reference pressure, is located outside the capsule. One or more capsules can be used to measure relative pressure.

Can capsules be used for measuring liquids? 

No, capsules cannot be used for liquids because they are not self-draining. Capsules are specifically designed for gas pressure measurement.

What are the types of pressure gauges? 

There are various types of pressure gauges, including Bourdon Tube, Diaphragm, Capsule, Absolute, Differential, Bellows, and Manometer Pressure Gauges. Each class is designed for specific applications in commercial or industrial settings.

Where are Capsule Pressure Gauges used? 

Capsule Pressure Gauges are used for pressure measurement at shallow pressures, especially for gaseous and aggressive media in harsh environments. They have a robust design with IP54 ingress protection, making them suitable for outdoor use.

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About Mariam Nazir Innovator   blogger

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Joined APSense since, October 4th, 2023, From boston, United States.

Created on Nov 16th 2023 02:45. Viewed 278 times.


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