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Need a formula for CFMby shellback
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#1
Mar310, 02:46 PM

P: 3

I just want the formula that shows how to find for CFM. I have the pipe diameter and the PSI that are available. I'm just using air, nothing special.



#2
Mar310, 04:19 PM

Sci Advisor
P: 2,283

CS 


#3
Mar310, 04:26 PM

P: 3




#4
Mar310, 05:06 PM

Mentor
P: 22,239

Need a formula for CFM
The pressure is the static pressure in the pipe? That isn't enough to determine the airflow. You need a differential pressure across an orifice, pressure drop in a venturi or velocity pressure from a pitot tube.
Once you get some form of velocity pressure (and if you give us more details about your setup, we can tell you how to measure/estimate it), you can use a form of Bernoulli's equation to find the velocity: V=4005*sqrt(Vp) where V= velocity in fpm Vp= velocity pressure in inches of water gauge. 


#5
Mar310, 05:12 PM

P: 3




#6
Mar310, 05:19 PM

Mentor
P: 22,239

That's static pressure. It doesn't have anything directly to do with velocity (consider an air tank pressurized to 100psi: no airflow at all). What is this pipe supplying? Or is it open ended?



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