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Posted by Glenn on August 20, 2007, 8:57 pm
: quoted-printable
What kind of games are they playing with HP now days?
My old air compressor had developed a rust hole in the tank and I am =
looking for another one.
The old one (probably 40 years old) is 2 HP and pulls about 20 amp, 230 =
as best as I can remember without looking. Saw one that was rated at 4 =
HP and ran on a standard 120 volt cord. In the vehicular, bull shit. =
Any real 4 HP motor should pull at least 30 amp, 230. Pulled out my old =
W W Grainger cat and didn't see a 4 HP but the 3 HP I saw pulled 21 amp =
230. That's 42 amp 115 and they are getting 4 HP out of a 20 amp 115?
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<DIV>What kind of games are they playing with HP now days?</DIV>
<DIV> </DIV>
<DIV>My old air compressor had developed a rust hole in the tank and I =
am=20
looking for another one.</DIV>
<DIV> </DIV>
<DIV>The old one (probably 40 years old) is 2 HP and pulls about 20 =
amp,=20
230 as best as I can remember without looking. Saw one that was =
rated at 4=20
HP and ran on a <STRONG>standard 120 volt cord.</STRONG> In the =
vehicular,=20
bull shit. Any <STRONG>real</STRONG> 4 HP motor should pull at=20
least 30 amp, 230. Pulled out my old W W Grainger cat and =
didn't see=20
a 4 HP but the 3 HP I saw pulled 21 amp 230. That's 42 amp 115 and =
they=20
are getting 4 HP out of a 20 amp 115?</DIV></BODY></HTML>
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Posted by CS on August 20, 2007, 9:31 pm
: quoted-printable
If you get a magnifying glass and get a good, close look at the HP =
rating, you'll see it says "Peak HP". Somewhere, sometime, during the =
operation of the motor, there is a slight possibility of a chance that 4 =
HP might be generated in some tiny location within the motor. This, of =
course, is perfectly useless to anybody, hence the fine print.
I've heard several well-intentioned samaritans suggest going strictly by =
the amps and volts in determining the actual power output, however, an =
inefficient motor will draw plenty of amps without doing all that much.
Other helpful folks suggest going strictly by CFM ratings. Personally, =
I feel it's naive to believe these figures aren't just as inflated as =
the HP ratings.
My method for buying tools such as air compressors, is to pick the =
brains of folks who use them to make a living. If they buy junk that =
falls apart in a hurry, they lose money, so they know what works. This, =
of course, doesn't apply to slugs who don't finish the job. (Yes, I'm =
talking about YOU Nick! Finish my damn bathroom!)
Oh yes, the point. If I were in your place, I'd try to match up the =
specs (volts and amps) of what's being replaced. Not only will this =
ensure you'll have the power to run the new rig without popping =
breakers, but you'll get at least as much, probably significantly more, =
CFM than with the old. Motors have come a long way in 40 years in terms =
of efficiency.
CS
What kind of games are they playing with HP now days?
My old air compressor had developed a rust hole in the tank and I am =
looking for another one.
The old one (probably 40 years old) is 2 HP and pulls about 20 amp, =
230 as best as I can remember without looking. Saw one that was rated =
at 4 HP and ran on a standard 120 volt cord. In the vehicular, bull =
shit. Any real 4 HP motor should pull at least 30 amp, 230. Pulled out =
my old W W Grainger cat and didn't see a 4 HP but the 3 HP I saw pulled =
21 amp 230. That's 42 amp 115 and they are getting 4 HP out of a 20 amp =
115?
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<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>If you get a magnifying glass and get a =
good, close=20
look at the HP rating, you'll see it says "Peak HP". Somewhere, =
sometime,=20
during the operation of the motor, there is a slight possibility of a =
chance=20
that 4 HP might be generated in some tiny location within the =
motor. =20
This, of course, is perfectly useless to anybody, hence the fine=20
print.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>I've heard several well-intentioned =
samaritans=20
suggest going strictly by the amps and volts in determining the actual =
power=20
output, however, an inefficient motor will draw plenty of amps without =
doing all=20
that much.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Other helpful folks suggest going =
strictly by CFM=20
ratings. Personally, I feel it's naive to believe these figures =
aren't=20
just as inflated as the HP ratings.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>My method for buying tools such as air =
compressors,=20
is to pick the brains of folks who use them to make a living. If =
they buy=20
junk that falls apart in a hurry, they lose money, so they know what=20
works. This, of course, doesn't apply to slugs who don't finish =
the job.=20
(Yes, I'm talking about YOU Nick! Finish my damn=20
bathroom!)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Oh yes, the point. If I were in =
your place,=20
I'd try to match up the specs (volts and amps) of what's being =
replaced. =20
Not only will this ensure you'll have the power to run the new rig =
without=20
popping breakers, but you'll get at least as much, probably =
significantly more,=20
CFM than with the old. Motors have come a long way in 40 years in =
terms of=20
efficiency.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>CS</FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV>"Glenn" <<A =
wrote in message <A=20
=
8$4c368faf@roadrunner.com</A>...</DIV>
<DIV>What kind of games are they playing with HP now days?</DIV>
<DIV> </DIV>
<DIV>My old air compressor had developed a rust hole in the tank and I =
am=20
looking for another one.</DIV>
<DIV> </DIV>
<DIV>The old one (probably 40 years old) is 2 HP and pulls =
about 20 amp,=20
230 as best as I can remember without looking. Saw one that was =
rated at=20
4 HP and ran on a <STRONG>standard 120 volt cord.</STRONG> In =
the=20
vehicular, bull shit. Any <STRONG>real</STRONG> 4 HP motor =
should pull=20
at least 30 amp, 230. Pulled out my old W W Grainger cat =
and didn't=20
see a 4 HP but the 3 HP I saw pulled 21 amp 230. That's 42 amp =
115 and=20
they are getting 4 HP out of a 20 amp =
115?</DIV></BLOCKQUOTE></BODY></HTML>
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Posted by Robert Allison on August 20, 2007, 9:44 pm
Glenn wrote:
> What kind of games are they playing with HP now days?
>
> My old air compressor had developed a rust hole in the tank and I am
> looking for another one.
>
> The old one (probably 40 years old) is 2 HP and pulls about 20 amp, 230
> as best as I can remember without looking. Saw one that was rated at 4
> HP and ran on a standard 120 volt cord. In the vehicular, bull shit.
> Any real 4 HP motor should pull at least 30 amp, 230. Pulled out my old
> W W Grainger cat and didn't see a 4 HP but the 3 HP I saw pulled 21 amp
> 230. That's 42 amp 115 and they are getting 4 HP out of a 20 amp 115?
That is because they use the "peak horsepower" rating or they
say it "develops" that horsepower. It is indeed a useless
rating. Whenever you are running a circular saw and it binds
in the wood and the blade stops, the saw develops its "peak"
horsepower. If you will notice, when this happens, the lights
may dim when the motor stops. For a brief moment, the motor
is pulling way more amps than what it was intended to do and
it has pulled its peak power.
Notice that while this is happening, the blade is stopped, so
it is incapable of delivering any power to help you work, but
it is pulling alot. Which is the main reason that the rating
is bullshit. Continuous horsepower is the only rating to use
and it works like this:
In perfect conditions, 746 watts is one horsepower. In real
time conditions, due to inefficiencies in both electrical
power delivery and the efficiency of the motor, a good number
to use is 1250 watts is one horsepower.
So,...if you have a machine made to plug into a 15 amp
circuit, 15 amps times 120 volts equals 1800 watts. Divide
1800 by 1250 and you have roughly 1.5 horsepower. The
amperage number is the one to use to select your next machine.
Here is an excellent article on motors in general, and
compressors in particular:
http://truetex.com/aircompressors.htm
--
Robert Allison
Rimshot, Inc.
Georgetown, TX
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Posted by Dennis on August 21, 2007, 4:46 pm
: quoted-printable
Got curious and looked on line at WW Grainger. =
(http://www.grainger.com/)
1st 3- HP capacitor start motor I looked at drew 33.8/16.9 amps, 115/230 =
volts (full load rating, service factor 1.15). Next one was 32.0/16.0 =
amps. Looking at 3- HP capacitor start, capacitor run, the draw was =
30.0/15.0 a. (service factor 1.00), next one was 33.6/16.8 a.=20
Things have come a long way in 40 years.=20
What kind of games are they playing with HP now days?
My old air compressor had developed a rust hole in the tank and I am =
looking for another one.
The old one (probably 40 years old) is 2 HP and pulls about 20 amp, =
230 as best as I can remember without looking. Saw one that was rated =
at 4 HP and ran on a standard 120 volt cord. In the vehicular, bull =
shit. Any real 4 HP motor should pull at least 30 amp, 230. Pulled out =
my old W W Grainger cat and didn't see a 4 HP but the 3 HP I saw pulled =
21 amp 230. That's 42 amp 115 and they are getting 4 HP out of a 20 amp =
115?
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<META http-equiv=3DContent-Type content=3D"text/html; =
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</HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>Got curious and looked on line at WW =
<FONT=20
face=3D"Times New Roman" size=3D3>Grainger. (<A=20
href=3D"http://www.grainger.com/">http://www.grainger.com/</A>)</FONT></F=
ONT></DIV>
<DIV><FONT face=3DArial size=3D2><FONT face=3DArial =
size=3D2></FONT></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2><FONT face=3D"Times New Roman" =
size=3D3>1st 3- HP=20
capacitor start motor I looked at drew 33.8/16.9 amps, 115/230 volts =
(full load=20
rating, service factor 1.15). Next one was 32.0/16.0 amps. =
</FONT></FONT><FONT=20
face=3DArial size=3D2>Looking at <FONT face=3D"Times New Roman" =
size=3D3>3- HP capacitor=20
start, capacitor run, the draw was 30.0/15.0 a. (service factor 1.00), =
next one=20
was 33.6/16.8 a. </FONT></FONT></DIV>
<DIV><FONT face=3DArial size=3D2><FONT face=3DArial =
size=3D2></FONT></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2><FONT face=3D"Times New Roman" =
size=3D3>Things have=20
come a long way in 40 years. </FONT></FONT></DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
<DIV>"Glenn" <<A =
wrote in message <A=20
=
8$4c368faf@roadrunner.com</A>...</DIV>
<DIV>What kind of games are they playing with HP now days?</DIV>
<DIV> </DIV>
<DIV>My old air compressor had developed a rust hole in the tank and I =
am=20
looking for another one.</DIV>
<DIV> </DIV>
<DIV>The old one (probably 40 years old) is 2 HP and pulls =
about 20 amp,=20
230 as best as I can remember without looking. Saw one that was =
rated at=20
4 HP and ran on a <STRONG>standard 120 volt cord.</STRONG> In =
the=20
vehicular, bull shit. Any <STRONG>real</STRONG> 4 HP motor =
should pull=20
at least 30 amp, 230. Pulled out my old W W Grainger cat =
and didn't=20
see a 4 HP but the 3 HP I saw pulled 21 amp 230. That's 42 amp =
115 and=20
they are getting 4 HP out of a 20 amp =
115?</DIV></BLOCKQUOTE></BODY></HTML>
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