Re: Conversion of PSI-CFM to Watts (or horsepower)

Hi Barry,

I didn’t have much time to spend on the detailed unit conversion aspect of question, but I found the following, very interesting link. It’s right on- topic for your question: http://www.truetex.com/air compressors.htm

There is apparently a lot of misinformation and misleading in the air compressors field/sector. The site above suggests that a good formula for the theoretical power required to compress 1 CFM of air by a single-stage compressor is, HP = 0.015*P*(R^0.29-1). P is 14.7 psi and R is the ratio of the compressed absolute pressure to the ambient air pressure (or 104.7/14.7 in your case of 90 psig).

The above equation gives 0.169 HP/CFM or about 1.7 HP for your 10 CFM case. Now, that is the minimum horsepower required, without considering any losses.

I hope the website I linked to can be of more help to you.

-Alex Tobias