On Wed, 30 Nov 1994, after I wrote:
> > I will compare two 5 hp units, a 4 hp unit, and a
> > 2 hp unit, all from CH.
> >
> > Campbell-Hausfeld 2 hp Single Stage: 7.2 cfm @ 40 psi max 125 psi
> > (115/230 v, 15 amps @ 115 volts) 5.6 cfm @ 90 psi
> >
> > Campbell-Hausfeld 4 hp Single Stage: 8.1 cfm @ 40 psi max 125 psi
> > (115 v only, 15 amps @ 115 volts) 6.4 cfm @ 90 psi
>
John Lupien replied:
> That can't be right. It must mean "230v only, 15 amps @ 230 volts".
> 15 amps at 115 volts is 2.3 hp, can't do any better, sorry...
>
And I now retort:
Well, what they said exactly was 120 volts, 15 amps. So I cheated a bit
by saying 115 volts, since I am not aware of a 120 volt supply being
something distinct from 115 volts. Maybe there is some subtlety here I
don't see. Maybe they *mean* 230 volts, but they said 120 in two
different catalogs. I know it doesn't add up; I said it doesn't add up.
I'm not a dummy, John.
But if, as you suspect, the 120 volts should read 230 volts, then you have
to explain why a 4 hp compressor that draws 15 amps @ 230 volts produces
about the same air output as a 2 hp compressor that draws 15 amps @ 115
volts.
I tried to call Harbor Freight to check, but got tired of being on hold.
It's 1-800-423-2567 if you want to try.
It does not matter; my point was that hp ratings should be taken with a
grain of salt as predictors of output. It's irrelevant, but I suspect
horsepower ratings should be taken with a grain of salt as expressions of
horsepower, too.
Ray Gibbons
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