Normally Randall would reply to this but I think he gets so tired of
saying it that I thought I would give him a hand :-)
Plus it would give me a chance to let him know I finally "got it".
The compressor rating of 12 cfm @ 80 psi really means that it sucks in
12 cfm at atmospheric pressure (14 psi) compresses it and spits it out
at 80 psi. If you double the pressure you reduce the volume by 1/2. So
the 12 cfm come in at 14 psi and go out at 80 psi.
14/80 = .175
1.75 X 12 = 2.1
So the compressor is really generating only 2.1 cfm at 80 psi not 12 cfm
at 80 psi.
Did I get it almost right Randall? :-)
Don Malling
Jack W. Drews wrote:
> At 11:11 AM 1/4/04 -0500, Gbouff1@aol.com wrote:
>
>> I initially purchased a $239.00 Sears oil-less,direct drive, 20 gallon,
>> compresser that was around 3.5-4HP. Two problems with this comprsser
>> is that I
>> quickly ran out of air when using an air sander or die grinder, but it
>> was fine
>> for short use of impact tools and such.
>
>
> I have a 5 hp compressor, relatively new, and it won't sustain the
> demand from any rotary sanding tool. Puzzled, I finally determined that
> the sanding tools generally require about 12 cfm @ 90 psi -- but the
> compressors generally put out 12 cfm @ 80 psi. I'm really disappointed
> that the measly 10 psi difference won't run the sander. It will run
> straight line sanders quite nicely, though. I'd appreciate input on any
> rotary sanders (commonly called DA's) that anyone has that will operate
> on less than 90 psi.
>
>
> uncle jack
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