CFM Calculation

Nov 09, 2006 2 Replies

Dear All, How do we calculate CFM required if the following data is available Compressed air pressure at 6kg/cm2



Cylinder Bore Stroke Cycles per minute



No 1 2" 2" 60 No 2 1 1/2" 1" 60 No 3 2 1/2" 4" 60



Is the data sufficient? Is there a general formula to calculate these type CFM requirements?



Regards Manju



Since the answer is to be in English units, if you needed this value, convert it to English units.

Bore = diameter of circular area. Calculate area in [ft^2] convert Stroke to feet. Stroke * Area-of-Bore = volume displaced per stroke Cycles per minute, assuming 1 draw-in stroke per cycle

[ft^2] * [ft/cycle] * [cycle/minute] = [ft^3/minute]

Where it gets difficult is when they want "standard" or "normal" CFM, to know the CFM when operating between two different pressures, to know the power required / available.

I assumed a simple cycle (1 draw stroke, 1 exhaust stroke). I assumed no head losses from the pressure source to the cylinder. I assumed they wanted the CFM required from the source. I assumed the exhaust is to *zero* pressure.

If your homework problem says something different than these, what I said is not correct.

David A. Smith

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