Calculating CFM from PSI

[ben3929]

How do I calculate compressed air flow rate in CFM using diameter of pipe, density of air, temperature of air, and pressure of air at drop station? I used the equation Q= (area^2)* sqrt((2*pressure/density)) but my result is not matching with the graph shown in the link below.

http://www.engineeringtoolbox.com/air-flow-compressed-air-pipe-line-d_1280.html

 

[zdas04]

You need a bit more information. Length of pipe? Pressure at the other end of the pipe? Gas viscosity? An equation that makes sense (area squared times the square root of pressure over density results in units of length raised to the fifth power per second. I would use the Isothermal Gas Flow equation and explicitly calculate a friction factor.

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[ben3929]

Perhaps let me try clarifying my question the following way."X" amount of pressure delivered to your car tire through "d" size pin hole tube. With known time "t" how much air volume fill the tire.

 

[IRstuff]

Well, for one, that cited page makes certain assumptions about what's at the end of the pipe, which is not the same as trying to fill a tire. Did you read the notes at the bottom of the graph? In your case, the pressure delta across the fill valve is constantly changing.

TTFN
I can do absolutely anything. I'm an expert!
faq731-376 forum1529

 

[zdas04]

Take a look at faq378-1864

David Simpson, PE
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist