home garage compressor: how many CFMs?

[Jim Haseltine]

Not an expert, this is just what I've picked up over the years.

Compressors are usually rated at cfm displacement or cfm free air delivery
(fad).
On the same compressor the displacement figure is higher than the fad figure
so guess which one is usually displayed in big numbers. Looking at the specs
that you've listed, I would think that the cfm are fad because I'd expect to
see displacement figures around 12 from a 6hp single stage and a little less
from a 4hp dual.

Tools usually have their consumption listed in fad with a minimum psi and
few will require less than 3cfm, with most needing 4-5cfm, some going up to
9-10cfm. The average min psi is around 90.
Spray guns are a different story.



Regards,

Jim Haseltine


---- Original Message -----
From: "Konstantin Bogach" <kbogach at comcast.net>
To: <quattro at audifans.com>
Sent: Friday, April 18, 2003 11:53 PM
Subject: home garage compressor: how many CFMs?


> Sorry for bringing it up again.  I remember seeing thread with similar
> topic some time ago but  I searched archives and  could not find the
> answer to my dilema.
> I need to buy a compressor and I am looking at two craftsman units:
> a) 6HP,  oil lub, horisontal style, single stage, 150 PSI max,  6.8/8.6
> cfm at 40/90 psi, 25 gallons
> b) 3.5HP, oil free, upright, dual stage, 175 psi max, 5.1/5.8 cfm at
> 40/90 psi, 25 gallons
>
> I like everything in b) except that I am concerned that I think that 5.1
> psi in on a margin where most tools work.  Is it right?
> Plus, I am not sure how they rate their compressors - conservatively (I
> doubt) or optimistically (most likely, I am afraid).  So, it could be
> 4.8, maybe.  b) works veru quiet, upright style attracts me too.  I am
> not going to run sanders. Both a) and b) have same price.
>
> I would appreciate if you share your experiece of how much CFMs you need
> to run most common tools and help me to make right choice.
>
> Thanks a lot in advance.
> Konstantin.
> 200tq '89  (about to start R134A conversion)
> 200tqa '89  (same as above)
> UrS4 '93
>
>