HomePressure MeasurementPressure Gauge | Complete Selection Guide

Pressure Gauge | Complete Selection Guide

Pressure Measurement is Very Important in Industry. In this article, I will give you complete information about the pressure gauge and its selection process.

Introduction

Pressure Gauges are very important Mechanical devices. It translates mechanical movement into Pressure Value.

Before we go into the selection process, we need to understand some basic concepts about Pressure Measures. As you all know Pressure is defined as a force per area.


Classification of Pressure

Before we start our article, we need to understand the types of Pressure we need to measure.

  • Absolute Pressure
  • Gauge Pressure
  • Differential Pressure
  • Vacuum Pressure

According to Types of Pressure, measuring gauges are selected accordingly. So, let’s understand the Types of pressure using Visual Representation.



As you can see, the above image represents what is the difference between Gauge Pressure, Absolute Pressure, Differential Pressure, and Vacuum Pressure.

People are mostly confused between Absolute Pressure and Gauge pressure. In simple language, the difference between Gauge and Absolute Pressure is Reference Pressure.

In Guage Pressure Atmospheric Pressure considers a reference ZERO and In Absolute Pressure, Absolute ZERO pressure Consider as a Reference ZERO.


Types of Pressure Gauges

There are many types of pressure gauges available in the market that are listed below.

  • Diaphragm Seal Type
  • Bourdon Tube
  • Bellow Type
  • Capsule Type

In this article, I only discussed the most commonly used Pressure Gauges in the industry.

  • Diaphragm Seal Type
  • Bourdon Tube Type
Courtesy to WIKA

Steps of Pressure Gauge Selection

Step – 1 | Process Medium and Physicals Property of Medium

As you can see from the working principles of the Bourdon tube and Diaphragm Seal type pressure Gauge you will find out that the Bourdon Tube type pressure Gauge is directly in Contact with the Process Medium.

If the process medium is corrosive and highly reactive then we have to select Diaphragm seal type Pressure Gauge.

When we have to measure the Pressure of viscose fluid then we have to consider Diaphragm type Pressure Gauges.

Because Viscous fluid is stuck in Bourbon tube and leads to Measurement Errors and Frequent Maintenance.

Step – 2 | Pressure Range

When we have to select a pressure gauge for low-Pressure Measures then we have to select a Diaphragm type pressure Gauge. Diaphragm type pressure gauge is measured up to 10 mbar.

Step – 3 | Over Range Protection

If our measuring Pressure is unstable and sometimes fluctuates more than its maximum operating pressure Limit.

And application required higher over range protection then we have to choose a Diaphragm Seal type pressure gauge

Step – 4 | Cost

And finally, we have to consider the cost of equipment. So, the Bourdon tube type pressure gauge is cheaper than the diaphragm seal type pressure gauge.


Pressure Gauges Protection

Pressure Gauge protection is very improving because Breakage and cracking of PG leads to Leakage of the Process fluid and created Hazardous Conditions.

There are multiple types of protection techniques that are used for protecting Pressure Gauges.

  • Fluid Filling
  • Syphon
  • Gauge Saver

Fluid Filing

The fluid filling is one type of Protection that protects the Pressure gauge from Mechanical Vibrations.

Because Mechanical Vibration Leads to Measurement error. Because Mechanical Vibration is caught by Mechanical Pointer available in Pressure Gauge.


Courtesy to WIKA

And Fluid Filling is Also protecting Gauges from Mechanical failure due to mechanical vibration.


Syphone

It is a clever mechanism to protect pressure Gauges from sudden pressure and temperature changes.


Syphone

Gauge Saver

Gauge Saver is a protecting device that protects gauges from overpressure.

PL1, Pressure Limitter / Gauge Saver
Courtesy to Precisionmass

Standards in Pressures Gauge

There are multiple standards available for Pressure Gauges that the industry needs to follow.

List of Pressure Gauge Standard

Sr No.Standard NumberStandard Name
1BS EN 875-1Bourdon tube pressure gauges
2BS EN 875-2Selection and installation
recommendations for pressure gauges
3BS EN 875-3Diaphragm and capsule pressure
gauges
Standards For Pressure Gauge

Accuracy Class of Pressure Gauge

No.Accuracy ClassAccuracy classes Limits of the permissible error
(Percentage of span)
10,6± 0,6 %
21 ± 1 %
31,6 ± 1,6 %
42,5 ± 2,5 %
54 ± 4 %

How are Bourdon Tube Type Pressure Gauges made?


EndNote: –

I think now you have a better idea about pressure gauges and their selection process. If you still have any questions then comment below, I will help you.

If you like this Article then you also like our previous article on Temperature gauges | Complete selection guide of temperature Gauge.

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Adminhttps://worldofinstrumentation.com
Instrumentation and Control Engineer | IAS Member

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