You'll be limited to a 5hp compressor. Single or two stage won't change the motor amperage.

Generally, at 230/240v, a true 5hp motor will draw 23/20 amps and a 7.5 hp motor will draw 34/31 amps. YMMV.

Trublue

 

I'm on my second low end 5 to 7 HP 60 gallon air compressor. The 60 gallon tank is not much use on these units for continuous use IMO. I currently have a Lowes Kobalt single stage and from dead start it pulls 15 amps and right before it cuts off it's pulling 21 amps (used amp probe).

If you are limited to 30 amp line, stay with a smaller unit and leave more room for other tools on the circuit. Good Luck.

 

Yep, most 230V motors are going to draw about 4 to 4.5 amps per running horsepower. Don't be fooled by some of the phony horsepower claims that rate "MAX" or "develops" hp, which is the stalled max horsepower not the running hp. You can buy cheap or you can buy quality, but you can't buy quality cheap. When it comes to good quality compressors, I am partial to Eaton.

http://www.eatoncompressor.com/page/page/504747.htm

 

... Don't be fooled by some of the phony horsepower claims that rate "MAX" or "develops" hp, which is the stalled max horsepower not the running hp...

The nameplate on my compressor motor lists the horsepower as "SPL". I think that stands for "Some People Lie".

 

im looking at 1200 dollars to spend but willing to go up . not over 3 grand though so i have to stay 5 hp then

 

Yep, limited to 5hp. If my shop wasn't in my basement I'd be all over this, http://portland.craigslist.org/mlt/tls/3733678064.html

The picture doesn't really reflect the size this thing is...that pump is physically huge. That 5hp Baldor motor is turning at 1725 RPM, the pumps probably 800 RPM. Big and slow...putting out 17+CFM @90 PSI.

That's what I'd be looking for in a compressor....the motor at 1725/1750 RPM and the motor below 1000 RPM.

I don't have an Eaton but they sure have nice specs. If only they weren't made in China (assembled in the US) they'd be perfect.

I'd look at Saylor Beal, Champion, Quincy and Jenny if my budget was reaching $3K.

Trublue

 

i think i will go with this one http://www.eatoncompressor.com/catalog/item/504747/206953.htm

Is this a good buy ? would it last me years ? im trying to stay closer to 1200 cause then i can get a air dryer to. they will be shipping it to NJ so OR would be far.

what is better about these brands Saylor Beal, Champion, Quincy and Jenny ?

 

Well, everybody has their own opinion based on their personal experience. I have used just about everything out there during my 50+ years of working and I like Quincy about as well as anything else, but their prices are higher than Eaton and their specs are less.

I like your choice. I am sure that you read the specs regarding low rpm motors, intercooler and aftercooler to lower moisture content, etc.

If I were buying a new 5 hp compressor today, I think that I would buy the one you picked.

 

Quincy makes a nice compressor, but personally, I don't believe for a second they have any more American made parts in them then Eaton. It's my understanding as of a couple years ago Quincy had an American and a Chinese division. I'm not sure where the product split is. In addition to that Quincy was bought by Atlas Corp out of Sweden, except for their Chinese division.
To get Disc valves rather than reed you have to go up to their pressure lubricated top of the line piston compressor. Eaton's come that way across the board. Dollars to dollars my money is with Eaton. Money is no object? Buy one of the pressure lubricated piston Quincy compressors or a rotary screw.

 

"spl" rated is a special category of motots, generally for air compressor use. Reputable motor manufacturers put that on there so they cant get sued when the compressor company overstates the power. for example, the 3hp 60 gallon kobalt compressor at lowes says 3.7 hp. The motor is a 3 hp 15 amp motor with a 1.2 service factor. It is labelled "spl" so kobalt can advertise the maximum service factor hp, even though the motor only actually puts out that much power in the few seconds befor the pressure switch cuts out.

 

thanks guys learning alot

 

for what it's worth, 1HP is roughly 745W when translated into the MKS system.

Line voltage X available amperage is also watts. 220V x 30A = 6600W.

So to see how many horsies you can get away with when you have 6600W available "on tap", is just a matter of division; 6600/745 = 8.85HP. BUT you now need to take into account compressor efficiency, for that 8.85HP has to include any kind efficiency loss in the compressor, since nothing is 100% efficient. This is where I'll stop because I don't know what the typical efficiency of an air compressor motor is, nor the accepted range of values.

 

Oscar, Don't forget about the start-up current of the motor. Compressors can pull a lot of current on start-up.