Air press / volume
by jcgerow on 08/24/03 at 11:31:32

Great site folks! I am setting up a bench for testing an air-turbine motor. I need : [i]"Source of clean dry, filtered air at 40 to 120deg F. Source to have a pressure range of zero to 50 psig (0 to 345kPa) and air flow up to [u]46 pounds per minute ( 20,87Kgm)."[/u] I am having trouble understanding the pounds per minute measurement. JC

Re: Air press / volume
by Robert Fogt on 08/24/03 at 22:02:44

Dry air has a density of 1.0 kilograms per cubic meter.

So, 20.87 kilograms per minute of air flow is the same as 20.87 liters per minute of air flow.

The formula I have is:

D = P / TR

D = density P = pressure T = temperature R = constant

For dry air R the constant is 287 Joules/Kelvin kilogram

But I am not sure of your situation, so I'll just try and provide information and hope it is what you needed.

Re: Air press / volume
by Robert Fogt on 06/11/05 at 01:19:03

Seems I incorrectly stated the density of air. A visitor corrected me and supplied the correct results below.

The correct value is 1.2250 kg/meter[sup]3[/sup], at 1.01325 bar (1 standard atmosphere) and 288.15 K (59 F, or 518.67 R)

Additionally, the text states that “20.87 kilograms per minute of air flow is the same as 20.87 liters per minute of air flow.” which is also incorrect, since 1 cubic meter is equal to 1000 liters. Thus, 20.87 kg/m flow would be 20870 lpm at standard atmospheric conditions.