Air compressor question

On Wed, 17 Sep 2003 20:08:08 -0700, "Tim Ward"
wrote:


"Rich S." wrote in message
...
Check out item 47065-2VGA at http://www.harborfreight.com/.

4-1/2 HP 21 GALLON CAST IRON VERTICAL COMPRESSOR
Two Built-in Universal Quick Connect Couplers for Convenient Air Hose
Connection
Long-life oil lubricated compressor with precision machined cast iron
sleeve
Twin capacitor motor with thermal overload protection
Wheel kit with 6'' wheels and ergonomic for smooth portability
Oil level indicator window for easy maintenance
Reduced vibration with rubber foot stabilizers
4-1/2 peak horsepower; 120 volt, 60Hz
125 PSI max; 4.4 CFM @ 90 PSI; 11.1 CFM @ 40 PSI
Shipping weight: 152 lbs.
$169.99

Rich S.

I dunno beans about air compressors, so maybe someone else can explain it to
me:
The usual wall circuit is 15 Amperes, times 120 volts peak is 1800 watts.
746 watts in a horsepower, so how do you get 4.5 HP out of a wall socket?

Tim Ward


You DON'T.....

John Ammeter

On Thu, 18 Sep 2003 03:10:59 GMT, John Ammeter
wrote:

On Wed, 17 Sep 2003 20:08:08 -0700, "Tim Ward"
wrote:


"Rich S." wrote in message
...
Check out item 47065-2VGA at http://www.harborfreight.com/.

4-1/2 HP 21 GALLON CAST IRON VERTICAL COMPRESSOR
Two Built-in Universal Quick Connect Couplers for Convenient Air Hose
Connection
Long-life oil lubricated compressor with precision machined cast iron
sleeve
Twin capacitor motor with thermal overload protection
Wheel kit with 6'' wheels and ergonomic for smooth portability
Oil level indicator window for easy maintenance
Reduced vibration with rubber foot stabilizers
4-1/2 peak horsepower; 120 volt, 60Hz
125 PSI max; 4.4 CFM @ 90 PSI; 11.1 CFM @ 40 PSI
Shipping weight: 152 lbs.
$169.99

Rich S.

I dunno beans about air compressors, so maybe someone else can explain it to
me:
The usual wall circuit is 15 Amperes, times 120 volts peak is 1800 watts.

Most of the circuits in our house are 20 amp with ground fault. There
is one 30 amp and my den has two 30 amp 220 volt outlets( for the ham
station)

746 watts in a horsepower, so how do you get 4.5 HP out of a wall socket?

Tim Ward


You DON'T.....

Ohhh come on John, you can too...It's just I use a 220 volt 50, or 60
amp socket like the one for the kitchen range:-)) Well that and it's
mounted on the surface and fed through conduit. It's gotta be close
to a 90 foot run from the breaker box. No, I didn't use #14
either:-))

Did I mention it's out in the shop too?

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)



John Ammeter

In article , says...


"Rich S." wrote in message
...
Check out item 47065-2VGA at http://www.harborfreight.com/.

4-1/2 HP 21 GALLON CAST IRON VERTICAL COMPRESSOR
Two Built-in Universal Quick Connect Couplers for Convenient Air Hos
e
Connection
Long-life oil lubricated compressor with precision machined cast iro
n
sleeve
Twin capacitor motor with thermal overload protection
Wheel kit with 6'' wheels and ergonomic for smooth portability
Oil level indicator window for easy maintenance
Reduced vibration with rubber foot stabilizers
4-1/2 peak horsepower; 120 volt, 60Hz
125 PSI max; 4.4 CFM @ 90 PSI; 11.1 CFM @ 40 PSI
Shipping weight: 152 lbs.
$169.99

Rich S.

I dunno beans about air compressors, so maybe someone else can explain
it to
me:
The usual wall circuit is 15 Amperes, times 120 volts peak is 1800 wat
ts.
746 watts in a horsepower, so how do you get 4.5 HP out of a wall soc
ket?

Tim Ward


2 answers Tim. It is common to run seperate higher amperage circuits
to larger users. For instance, your electric range is probably on a
seperate circuit (but 220 volts). In a shop, it is common to have
seperate circuits to each of several higher powered machines.

The real kicker here is the way the ad is worded. They use the term
"peak horsepower" which could be defined anyway they want.... such as a
30 second life span They carefully fail to mention the recommended
breaker size or normal current drawn which would indicate the real
world horse power. It is much more effient to run larger motors on
220 volts so you can be certain that this motor is actually much lower
in real horsepower.

The usual wall circuit is 15 Amperes, times 120 volts peak is 1800 watts.
746 watts in a horsepower, so how do you get 4.5 HP out of a wall socket?

If it were DC, you'd be correct. AC has more or less sinusoidal voltage
and current, not necessarily peaking at the same time, and a whole bunch
of other stuff I used to know about.

Ed Wischmeyer

"Ed Wischmeyer" wrote in message
...
The usual wall circuit is 15 Amperes, times 120 volts peak is 1800
watts.
746 watts in a horsepower, so how do you get 4.5 HP out of a wall
socket?

If it were DC, you'd be correct. AC has more or less sinusoidal voltage
and current, not necessarily peaking at the same time, and a whole bunch
of other stuff I used to know about.

Ed Wischmeyer

Yep, but that makes it worse, not better. I'd expect RMS power to be about
70 % of that 1800 watts.
That's about 1300 watts, or less than 2 HP.

Tim Ward

"Tim Ward" wrote in message
...

Yep, but that makes it worse, not better. I'd expect RMS power to be about
70 % of that 1800 watts.
That's about 1300 watts, or less than 2 HP.

Well, if 4.5 hp out of a wall socket isn't enough, how about this one???

Rich "To infinity and beyond!" S.

6 HP, 20 GALLON COMPRESSOR

Oil-free design for lower maintenance. Easy-grip cushioned handle.
Quick-connect, regulator, dual gauges and tool tray.
Horse Power: 6
Power supply: 120V
Air pressu 135 PSI maximum
Air Delivery:
@ 40 PSI: 8.3 CFM
@ 90 PSI: 5.8 CFM

Tank size: 20 gallon
Shipping weight: 100 lbs.


Porter Cable# CPF6020

ITEM 45158-1VGA
$299.99

On Wed, 17 Sep 2003 20:55:03 -0700, Ed Wischmeyer
wrote:

The usual wall circuit is 15 Amperes, times 120 volts peak is 1800 watts.
746 watts in a horsepower, so how do you get 4.5 HP out of a wall socket?

It's probably more like 15 or 20 amps and that is 115 to 120 volts
RMS, not peak. Peak is 1.414, or roughly 162 volts. On single phase
they current and voltage should be close enough for all practical
purposes to call them in phase. (except during starting)

If it were DC, you'd be correct. AC has more or less sinusoidal voltage

So, using RMS at 115 volts he's still close.

and current, not necessarily peaking at the same time, and a whole bunch
of other stuff I used to know about.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)


Ed Wischmeyer

"Tim Ward" wrote in message
...

I dunno beans about air compressors, so maybe someone else can explain it
to
me:
The usual wall circuit is 15 Amperes, times 120 volts peak is 1800 watts.
746 watts in a horsepower, so how do you get 4.5 HP out of a wall socket?


The 120VAC is not the peak voltage, it's the RMS voltage. The peak voltage
of a 120VAC system is around 170V. If you take peak volts X peak amps, you
get peak VA, then multiply it X the power factor to get the peak watts,
divide by 746 / %effeciency to get peak HP. errrr.... I think.

"Frederick Wilson" wrote in message news:2uX9b.372665$Oz4.149020@rwcrnsc54...

Fred Speculating I wonder what the average time difference is between
deciding to build an airplane and actually starting the project.

Define "starting the project" :-)

Corrie (owner of several sets of plans, a bunch of tools, and a small
amount of wood)
http://www.itasca.net/~corrie/homebuilt_plane_blog.htm