Frank's comments are dead on - when buying a compressor, look at flow and
PSI, ignore horsepower. He is not right about the 1.25 horsepower IF you
allow 220V as well.
Here are two specific compressors I have, to illustrate his point (compare
these to the "5 HP" compressors sold at harbor freight or home depot or your
local big box hardware store)
1. sears compressor, 2 hp, about 25 years old, 7.3 CFM at 60 psi (this is
more than the "5 hp" compressors, in fact it's more than the "8 hp"
compressors I've seen). When I used this to paint a car, where it had to
deliver at rated capacity for an hour or so, the compressor got hot enough
to burn off the paint from the head, and I had to rebuild it because of a
cracked ring. I found it could run my small sandblaster for about 20
seconds before the tank would be empty and I'd have to let pressure build up
again.
2. my main compressor is a Quincy with a 5 horsepower motor - 19.5 CFM at
160 PSI - two cylinders with an intercooler. It weighs about 400 pounds if
I remember right - note that this is a "real" 5 hp, and the compressor is
properly sized - the compressor itself is about 24 inches high, 18 inches
deep and 18 inches wide and has an oil pump to pressurize the bearings (and
an oil pressure gauge as well). Because it has an intercooler, the air is
much dryer than I get from the Sears compressor. And, this one can deliver
its rated air all day without over heating.
I got the quincy compressor for about $800, rebuilt, from an industrial
compressor rebuilder - I'm very happy with it - I'd suggest that you
consider a used industrial compressor if you have any need at all for
anything more than occasionally blowing up a bicycle tire. I use air
sanders on my wood turning, they are much nicer, no heating of the motor,
better control, less noise -
"Frank Luet" wrote in message
...
I've just reviewed the thread and here are a couple of thoughts.
1. Most of the HP ratings you see on retail compressors are "Peak" which
is more a measure of the inertia in the motor than a true measure of its
power. A motor converts electrical power to mechanical. The maximum
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