Gas to Air Volumetric Flow Rate Conversion Formula.

[Pavan Kumar]

Hi All,

Can anyone share the formula to convert Volumetric flow rate of gas ( Q, Actual,gas) at actual conditions to volumetric flow rate of air at standard conditions ( Q, Std, Air).

Thanks and Regards,
Pavan Kumar Yarala Padmarao

 

[Latexman]

Gas Laws

Good Luck,
Latexman

 

[Pavan Kumar]

@ Latexman (Chemical) I did mean converting the flow rate from actual to standard conditions for the same gas but between gas and air.

Thanks and Regards,
Pavan Kumar Yarala Padmarao

 

[Latexman]

Then you input the proper molecular weight ratio.

Use Search. I found the reverse of what you seek. Maybe it will help. thread404-190397

Good Luck,
Latexman

 

[LittleInch]

I don't understand this question.

Surely one cubic metre is the same volume regardless of what is in it, air or gas. Mass is different but not volume.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[katmar]

Any rule of thumb type formula will have to have various assumptions built into it - eg what happens to the friction factor, temperature change etc. What are you actually trying to achieve? It would be better to just calculate the flow rate (or pressure drop or line size - whatever you are looking for) properly for the actual gas and conditions you are faced with, and forget about what might happen with air.

Katmar Software - AioFlo Pipe Hydraulics

http://katmarsoftware.com

"An undefined problem has an infinite number of solutions"

 

[Pavan Kumar]

Dear katmar (Chemical),

I should have explained the background behind my questions. We have a API 650 storage tank and are checking the adequacy of the existing vent. I calculated the emergency venting rate in terms standard ft3/hr. of Air and wanted to get the equivalent ft3/hr. in terms of the tank vapors. API 2000 gives the emergency venting rate in standard ft3/hr. of air.

I was looking for a formula to convert the venting rate in terms of air to the tank vapor.

I found something in the internet and wanted to check if it is correct. Please check the link copied below. I wanted to know the reference for and basis for this conversion.

http://webwormcpt.blogspot.com/2008/09/two-useful-equations-for-flow.html

Thanks and Regards,
Pavan Kumar Yarala Padmarao

 

[LittleInch]

That equation you quote in the link is, I think, actually also converting volume based on mass.

Process engineers love to work on mass not volume and convert at the last minute.

This though is different.

A cubic metre of gas and a cubic metre of air at the same temp and pressure take up the same volume. Not the same mass, but if mass has nothing to do with it then it doesn't matter.

Either way if this is an API650 tank then the pressure is pretty close to atmospheric so I don't understand why you're doing this.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[vt2012]

API 2000 Annex D explains the derivation and ultimately simplifies an equation for an ideal gas to convert actual to standard. See equation D.37, but make sure you fall within the assumptions laid out in D.9.2.6.