Machines Theory

Understanding Diaphragm Pressure Gauge

A diaphragm is a material that is elastic and will displace if pressure is applied to it. The elastic property of the diaphragm will be used to determine the difference between the reference and unknown pressures in this sort of pressure gauge. The bourdon gauge’s functioning principle is the same as this device. The main difference between this gadget and a bourdon gauge is that it has a corrugated diaphragm rather than a bourdon tube. If we attach this gadget to any gauge point, the diaphragm will deform elastically. This type of pressure gauge is commonly utilized due to its small size. Low-pressure applications are best served by the diaphragm pressure gauge.

In this article, you’ll get to know the definition, applications, parts, diagram, types, working, advantages, and disadvantages of a diaphragm pressure gauge.

Diaphragm pressure gauge

Read more: Understanding Pressure Gauge

What is a diaphragm pressure gauge?

A pressure gauge with a diaphragm is a pressure gauge that measures pressure using a diaphragm. The term diaphragm refers to a flexible material, also known as a membrane, that is typically constructed of thin metal, leather, rubber, cloth, or other similar materials. The membrane device is used to measure the difference between two different pressures, and the working principle of the pressure gauge with a diaphragm is based on the resilience properties of metal / thin plate due to the curvature of iteration pressure at the membrane plane.

The membrane separates the pressure gauge’s inner working components from the media, preventing contamination. The diaphragm pressure gauge can be used with corrosive or contaminated liquid or gaseous media because of this feature.

Applications of a diaphragm pressure gauge

Several industries have successfully used diaphragm pressure gauges for both absolute and differential pressure measurement applications. It is suitable for usage in applications where purity is sought due to its capacity to separate media and avoid contamination. It’s also suitable for industries that work with corrosive fluids. The following industries may benefit from the use of a diaphragm pressure gauge:

  • Food and beverage
  • Pharmaceutical
  • Petrochemical
  • Mining

The diaphragm pressure gauges are also used in vacuums, air compressors, hydraulic applications, as well as swimming pool filters.

Diagram of a diaphragm pressure gauge:

diaphragm pressure gauge diagram

Read more: Understanding Pressure Gauge

Types of diaphragm pressure gauge

The following is the various types of diaphragm pressure gauge:

Metallic diaphragm gauge:

It is constructed consisting of a thin, flexible diaphragm made out of brass or bronze. The diaphragm moves, which controls an indicating or recording instrument. Because this sort of gauge may work in any position and is portable, it is highly suited for use or installation in moving equipment like airplanes.

Slack diaphragm gauge:

Because the fluctuations are minor, measuring pressure below atmospheric pressure is more challenging. Only 14.7 psi (1 kg/cm2) separates air pressure from the complete vacuum. It is more difficult to measure pressure here.  Overpressure ranges as low as 0.01- 0.40 mm Hg, and a slack diaphragm gauge with a weak spring and a big area can be employed (torr). It is possible to attain 1-2 percent accuracy.

Working Principle

The working of a diaphragm pressure gauge is less complex and can be easily understood. Considering the figure, it is made up of a diaphragm (B), which is a thin circular metal sheet that can be flat or corrugated. When pressure is applied, the diaphragm deflection should be linear. Only tiny deflections may be guaranteed with a flat diaphragm. As a result, a corrugated diaphragm is chosen for industrial applications. The diaphragm can be welded or clamped in place between the flanges. In clean applications, the welded diaphragm is normally preferred to avoid any potential leakage.

The diaphragm divides the environment within the gauge, allowing one side to be exposed to the ambient while the other is sealed. When working with corrosive or viscous fluids, this media separation protects the internal gauge components.

The diaphragm deflects as pressure is introduced to the system through the inlet (D). This deflection is translated into pointer (C) movement via the link (A) and gears, resulting in a precise measurement of the change in pressure. The pressure is commonly expressed in bar or psi (pounds per square inch), and the maximum deviation is indicated by several accuracy grades.

Read more: Understanding a Pressure Relief Valve

Watch the video below to learn more about the working of a diaphragm pressure gauge:

Advantages and disadvantages of a diaphragm pressure gauge

Advantages:

  • They are quite sensitive.
  • It has the ability to detect fractional pressure variations in the microsecond range.
  • It merely requires a smaller amount of area.
  • Low pressure, vacuum, and differential pressure are all measured with this sort of pressure measurement apparatus.
  • It is suitable for usage in corrosive environments.

Conclusion

A pressure gauge with a diaphragm is a pressure gauge that measures pressure using a diaphragm. The term diaphragm refers to a flexible material, also known as a membrane, that is typically constructed of thin metal, leather, rubber, cloth, or other similar materials. That is all for this article, where the definition, applications, parts, diagram, types, working, advantages, and disadvantages of a diaphragm pressure gauge are been discussed.

I hope you learn a lot from the reading, if so, kindly share with other students. Thanks for reading, see you around!

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