question about pipe flow

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Joined: Tue Apr 29, 2014 3:43 pm

question about pipe flow

Post by rms4067 » Tue Apr 29, 2014 3:50 pm

I know very little about gas so please excuse my ignorance.

I've have looked and tried to figure out my question but can't quite get it.

I have a 2" (2.067 id) pipe with natural gas flowing through it. It is regulated from 5 psi to 1 psi with a fisher cs800 regulator. I need to know what the volumetric flow rate is in CFH. Everytime I try to calculate it I run into the fact I need to know the velocity. However, as I understand it, I need the volumetric flow rate to calculate the velocity.

Thank you for any help you guys can provide.

Also, please no links to the broken gas piping calculation website because it doesn't work.

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Re: question about pipe flow

Post by admin » Tue Apr 29, 2014 11:24 pm

You can't calculate flow rate with data you provided. You have to know more. Regulator should keep outflow pressure at constant value regardless of inlet pressure and flow rate, so for any flow rate pressure should be at set point, if flow is within regulator capacity. If your question is how much gas can flow through regulator at maximum it depends on Cv or Cg coefficient for that calculator which you should get from manufacturer prospect. With that coefficient you can calculate regulator maximum possible flow rate which is when regulator's obturator is in the most opened posssition.

Regarding your problem with web page with calculator opening can you please provide more information so maybe I can help you to use calculators. You can read instructions of possible reasons for calculator opening problem at: ... ctions.php
Pipe flow calculations - since 2000

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