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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