compressor question

[Rockers]

Am I right by saying the most important fact is the airflow at 100psi? It is to my understanding that most compressors have lower airflow at higher psi and vis versa of course. Just wondering, here in Japan all compressor manufacturers state the max airflow at the max pressure but never did I see any figures showing the airflow at lower pressure settings. Maybe that`s why most 7.5HP compressors I came across here don`t look at first sight suitable because they state the max airflow at max pressure.

[ScreenFoo]

I'd be interested in checking out references on this too--as it was told to me, there is a CFM displacement of the piston, and the actual CFM delivery goes down slightly as pressure increases, so if it delivers, say, 30CFM at 175PSI, it will only deliver, say, 33 at 100PSI.  For short duty cycles though, the higher pressure will come into play--we have a 120 gallon receiver, and a ten horse compressor, and it will go from 120-150 PSI in less than two minutes--at 150 PSI, functionally, it's more like 180 gallons of 100 PSI air.

If that helps at all.   

[Doug S]

Yes you are right.  It's hard to find the cfm rating at lower at a lower psi on most compressors I guess you'd have to call the manufacturer.  We had a M&R diamondback and it required 23 cfm at 100 psi.  Our 7.5 horsepower Champion series compressor states that it will produce 25 cfm at 175 psi.  It ran the press just fine.  Now we have a Sportsman e that has a servo drive and only requires 9 cfm at 100 psi.  The compressor only comes on about every 70 to 80 shirts.