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Re: (no subject)

To: fogbro1 <fogbro1@bellatlantic.net>, Ajhsys@aol.com
Subject: Re: (no subject)
From: Barney Gaylord <barneymg@ntsource.com>
Date: Fri, 27 Oct 2000 22:24:53 -0500
At 07:42 PM 10/27/2000 -0400, fogbro1 wrote:
>5.5 HP, 110 volt? C'mon......

Hey, I'm with you.  Whatever happened to truth in advertising (as if there
ever was such a thing)?  1 HP = 746 watts, right?  Start by checking the
amperage rating on the motor.

Now that compressor has a wall plug for 120 VAC and 15 amps.  Since there's
no guarantee that any 15 amp outlet would be fused with anything larger
then a 15 amp circuit breaker, and circuit breakers have a general
tolerance of +/- 20% for trip current, you can't draw any more than 12 amps
from a 15 amp circuit without high risk of it tripping out.  So, 12 amps x
120 volts = 1440 watts, or 1.93 HP maximum of power consumption, which
coincidentally rounds off to 2 HP, which is significant (get there in a
second).  Also if the motor is as much as 94% efficient (which it probably
isn't considering the source), then the actual power output would be no
more than 1.93 x .94 = 1.81 HP.

Now also check the air delivery rating.  Just for an interresting
comparison, I have a belt driven two cylinder "Craftsman" compressor with
20 gallon horizontal tank and 2 hp motor, which fits nicely under my work
bench.  Air delivery rating is:

11.7 CFM displacement
9.0 SCFM at 40 psi
7.5 SCFM at 90 psi

Reason is because it's a real 2 HP rating.  So now how does that noisy
direct drive 5.5 HP compressor compare?  About the same at low pressure,
and maybe not so good at high pressure.

Now would anyone like to clarify how they "legally" get away with these
outrageous power claims?  Heck, if I could get away with that, my stock MGA
1500 has about 200 horsepower (which it does, by the same logic).

Barney Gaylord
1958 MGA with an attitude (and a little logic)
    http://www.ntsource.com/~barneymg


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