Curtis 80 gal 3hp compressor

Get the serial # and call the factory?

Now you're talking. Jeez, when I see the guys talking about spending $500 to get some Husky unit from Homo Depo it drives me nuts.
Hopefully it's under power. Check it when you get there -- if it has air in the tank, crack the drain valve. If a whole lot of rusty water comes out, that's *not* good. However, that's what happened to me with my Quincy, and that sucker's been humming along for years now, so it isn't a showstopper. But definitely a bargaining point.
Look closely at the air cleaner. It should look pretty good. If it has big gaping holes in it and is all black, that means you can pretty much count on having to rebuild the pump.
Pull the dipstick and look closely at the oil. Get it in the light -- any floating metal specks? Smell it -- does it smell clean?
Run the machine. Listen for knocking. Let it pump all the way up and shut off by itself. Note the pressure. For a good 2-stage unit it could be as high as 175 psi. If it's way down at 90 ask the guy why. If he is ignorant, that's a bad sign. When it's fully stopped pumping, listen for air leaks.
It will almost certainly be a 3 phase motor. I used to have the impression that air compressors weren't suitable for running from a phase converter, but recently that has been pooh-poohed so you may be able to. Just be aware of the input power requirement, and consider how you will meet it.
If you buy it, be careful moving it. Air compressors, whether horizontal or vertical, are very top-heavy. Don't move the truck even one inch without the unit secured. If it falls over it can do $400 damage to itself in the blink of an eye. (Happened to me just moving my truck in my driveway after making it home 30 miles -- I was lucky and was able to cheaply fix mine!)
GWE

I did some math on how big a 80 gal compressor must be. 4 ft diameter by 6+ ft tank. It is probably a real monster and will not fit into my garage's free space. I promised to look at it tomorrow, so I will report my findings, but it is unlikely that I will buy it.
i sorry for typos, I am drunk at the moment.

he says it goes up to 125.
he says it is a 2 phase.
thanks.
thanks grant, I am awfully drunk for some strange reason (drank less than a glass of wine), I am barely typiung.

A 4' dia X 6+' tank would be about 80 cubic feet, or around 600 gallons.
Ned Simmons

If the tank is U.S. made, it will most likely have an ASME type certification tag welded to the tank. That tag will show the volume capacity (gallons), maximum working pressure and the date it was manufactured. MAWP 150 PSI @ 650F, for example on a 125 PSI compressor. My 60 gal tank is about 20" x 46"
Scroll down the page to the section SIMPLEX TANK MOUNTED ELECTRIC - SINGLE STAGE 95-125 PSI
See the 3 HP Model CVM-808A 80 Gal unit. The dimensions aren't shown, but it's weight is listed as 565 lbs. I suppose the V in the model indicates that it's a vertical tank model. That would probably be about 2' wide x 6' overall height.
$400 doesn't buy a quality new compressor. If you can't hear it run, it could be a risky purchase, but you buy govt surplus, so offer what you're comfortable with. If it's a good running, good looking, late model unit, it will very likely get sold quickly.
You'll need to have/wire a 240V circuit with maybe 35A capacity.
WB ...............

Thanks. I suspect that it will be sold by the time I get to see it tonight. Too bad.
That's no problem, I have a subpanel in my garage. I would hard wire the unit.
i

I saw a (true)7.5 HP, 80 gallon cast iron Husky at HD that actually looked pretty robust. But they want $1,650, which will buy you an IR T-30, at least a 5 HP, IIRC.

He says it is 2 phase. What he means is 240VAC single phase service. There is any 2 phase power in the US. Ok, there is some but it very limited and very obscure. Some sections of the "old" parts of the country still have some 2 phase installations. I think around Philly mostly.
JW

I was drunk yesterday, it is a 1 phase motor. 3 hp. I put up pictures and posted them in a thread "Bought a curtis compressor".
i