#WishIknew – What are gas laws, standard volumes, and gas mass flow?


When you have a question about process automation that needs a short answer, let us know with #WishIknew and #Visaya! We’ll reply with a #WishIknew post. It’ll give a quick explanation, then some related articles, videos, or reviews if you want to know more.

I wish I knew what gas laws, standard volumes, and gas mass flow are!

Kind of a lot to stuff into one question! But you have to know the basics in physics to figure out problems in applications and find the right solutions. And you need to know your way around gas laws, standard volumes, and gas mass flow if you want to measure gas flow. Depending on your meter and your product, knowing can make a big difference.

So I tried to find the best way to explain these concepts, because they’re very technical and academic. Let me know if this post doesn’t give you the answers you want, and I’ll try again!

Gas laws

Different types of gas can still behave similarly, and we base the gas laws on that fact. So the behavior of these gases will depend on their volume, temperature, and pressure.

You have two types of gases, ideal and non-ideal gas. Ideal gas is a theoretical concept described using two principles.

The first one, Gay-Lussac’s law, explains gas expansion, covering the relationship between pressure, volume, and temperature.

Image result for Gay-Lussac's law gif
Courtesy of Docsity


The second one, Boyle’s law, explains how the pressure of a gas can increase as soon as the volume of a vessel or container decreases.


Image result for Boyle's law gif
Courtesy of Docsity


The formula for the ideal gas law looks like this:


  • P = pressure
  • V= volume
  • T= absolute temperature
  • n  =number of moles of gas
  • R= ideal gas constant

Ideal gas particles never interact with each other. Although this concept is theoretical, most real gases generally follow it. And non-ideal gases don’t follow the gas laws under any conditions.

Standard volume

This one is super easy! The standard volume of a gas is its volume at standard pressure and temperature.

Gas mass flow

To measure gas flow, we usually go with the mass flow. Why? Because it doesn’t depend on temperature or pressure. We can describe mass flow as the actual volume flow multiplied by the fluid density.

This video about gas laws can tell you more:

Related tags: #WishIknew Basic devices English Flow Gas laws Mass flow mass flow measurement Measurements Principle
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