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Re: Air Compressor

To: Brian Haskett <haskett@applink.net>
Subject: Re: Air Compressor
From: "W. R. Gibbons" <gibbons@northpole.med.uvm.edu>
Date: Mon, 3 Mar 1997 09:51:01 -0500 (EST)
On Sat, 1 Mar 1997, Brian Haskett wrote:

> The air compressor that was on loan to me has been returned to its owner,
> and I am now in the market to buy one.  I was looking at the
> Campbell-Hausfield 6HP 60 gallon upright for just under $400.  It's rated
> at 10 SCFM at 90 PSI.  The price is right about at the limit of my budget,
> so it looks like a good choice for me.  After talking to my neighbor
> today, though, I am not so sure that its the right thing to do.  He
> pointed out that it's very inefficient because it takes 6 HP to only
> deliver 10 SCFM @ 90PSI.  The two-stage compressors (which cost twice as
> much) deliver a lot more SCFM with less horsepower, so he argues that the
> the one that I am looking at will cost me a lot more money in the long run
> because of the increased electric bill.
> 
> Opinions ?
> 
> BTW- I will be using the compressor for automobile restoration  and
> household use.  I figure the 6HP unit will handle everything except
> sandblasting.  Is this reasonable ?

He is correct about the efficiency, but the problem is that the 6 HP 
rating on most 6 HP compressors is wildly optimistic.  It is probably a 3 
HP compressor at best.

The 2 stage will deliver a lot more air at the same HP, true.  The 
cheapest I've seen are in the $900 range.  It would take a very long time 
for the lower electric bills to recover the difference if you are not 
going to be running the thing continuously.  I would think your 
assessment is correct, the CH 6 hp will handle everything except 
sandblasting.  In fact, it will do that, if you're patient and use a 3/32 
nozzle on a pressurized sandblaster.

If you were a service station and planning to have the compressor running 
18 hrs per day, I would certainly say your neighbor is right.  For 
intermittant home use, I think the 6 hp CH will serve you well.

   Ray Gibbons  Dept. of Molecular Physiology & Biophysics
                Univ. of Vermont College of Medicine, Burlington, VT
                gibbons@northpole.med.uvm.edu  (802) 656-8910


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