Compare the Difference Between Similar Terms

Difference Between

Home / Science & Nature / Science / Physics / Difference Between Absolute Pressure and Gauge Pressure

Difference Between Absolute Pressure and Gauge Pressure

May 31, 2011 Posted by Olivia

Absolute Pressure vs Gauge Pressure

Pressure is an important concept in physics and finds scores of industrial and daily life. It is defined as force per unit area when it is applied in a direction perpendicular to the surface of the body on which it is applied. But what we measure with devices designed to measure pressure (such as manometer) is gauge pressure and not absolute pressure. This gauge pressure is always relative to the atmospheric pressure. Being a scalar quantity, pressure has no direction, and hence it is wrong to talk of pressure in a particular direction. The units of pressure are Newton per square meter or Pa, but there are many other units (non SI) of pressure such as bar and PSI also. This article will attempt to find differences between absolute and gauge pressure.

Pressure is often measure in terms of depth of a column of mercury because of the high density of mercury but it often gives erroneous results given variations in density and gravity with changes in temperature and location. This is why other units of pressure such as torr and ATM are used instead of mm of Hg.

One can measure either absolute pressure or gauge pressure. It is important to know which pressure you need as otherwise your measurement may be wrong and may have an error of up to one bar. Most commonly used pressure reference is gauge pressure and you know that it is gauge pressure when you see the letter g suffixed after the result (such as 15 psi g). This implies that the pressure measured is obtained after subtracting atmospheric pressure. Absolute pressure is a reading that is taken in reference to absolute vacuum. To measure absolute pressure, it is necessary to seal a high vacuum behind sensing diaphragm of the device.

Absolute pressure = gauge pressure + atmospheric pressure

Gauge pressure = absolute pressure – atmospheric pressure

This is simply because absolute pressure is zero referenced against perfect vacuum whereas gauge pressure is zero referenced against ambient air pressure.

In general, if you want to measure pressure that is influenced by variations in atmospheric pressure, you will have to measure gauge pressure as it will give you a reading that reflects pressure minus atmospheric pressure. However, if you want readings that are not influenced by atmospheric pressure variations, then you will have to use absolute pressure sensor.

Related posts:

Difference Between Force and Pressure Difference Between Density and Specific GravityDifference Between Density and Specific Gravity Difference Between Evaporation and Boiling Difference Between Boiling and Evaporating Difference Between Online Banking and e-Banking

Filed Under: Physics Tagged With: absolute pressure, absolute pressure sensor, absolute vacuum, ATM, atmospheric pressure, Bar, gauge pressure, Hg, manometer, measuring pressure, Newton per square meter, Pa, pressure, PSI, PSI g, SI unit of pressure, torr, units of pressure

About the Author: Olivia

Olivia is a Graduate in Electronic Engineering with HR, Training & Development background and has over 15 years of field experience.

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Request Article

Featured Posts

Difference Between Coronavirus and Cold Symptoms

Difference Between Coronavirus and Cold Symptoms

Difference Between Coronavirus and SARS

Difference Between Coronavirus and SARS

Difference Between Coronavirus and Influenza

Difference Between Coronavirus and Influenza

Difference Between Coronavirus and Covid 19

Difference Between Coronavirus and Covid 19

You May Like

Difference Between VirtualBox and VMware and Parallels

Difference Between Salk and Sabin Polio Vaccine

Difference Between Salk and Sabin Polio Vaccine

Difference Between Thai and Chinese Food

Difference Between Webcast and Podcast

What is the Difference Between Chlorhexidine Gluconate and Chlorhexidine Diacetate

What is the Difference Between Chlorhexidine Gluconate and Chlorhexidine Diacetate

Latest Posts

  • What is the Difference Between Coconut Oil and Virgin Coconut Oil
  • What is the Difference Between Wintrobe and Westergren Tube
  • What is the Difference Between Coarctation and Hypoplastic Aortic Arch
  • What is the Difference Between Acquired Brain Injury and Traumatic Brain Injury
  • What is the Difference Between Sensory and Cerebellar Ataxia
  • What is the Difference Between Corneal Ulcer and Corneal Opacity
  • Home
  • Vacancies
  • About
  • Request Article
  • Contact Us

Copyright © 2010-2018 Difference Between. All rights reserved. Terms of Use and Privacy Policy: Legal.