Air compressor advice

DuckHunterJon · Mar 9, 2010

Before going to far, let me first appologize for another air compressor post. I have searched and read every compressor related post for the past couple of years, and am still up in the air.

My question is fairly specific. I'm looking at a couple of compressors for shop use. It will be used for automotive (wrenches), wood shop (nailers), and a metal shop (grinders, plasma cutter, drills, etc) as a hobbiest. I'd also like to do some very limited sandblasting (I've done enough comercial blasting to know keep it small, or farm it out!).

My budget is fairly limited to $400.

My options are new entry level 60 gal (Kobalt, Husky, CH, etc) 3hp single stage for right around $400. For used, I have been looking for a while, the only decent one I have come across is a Quincy QR-25 model 325 that is approx 50 yrs old (but newer 60 gal tank) for $350. My issue is the Quincy is rated 8.28 ACFM @ 175 PSI (at 400 rpm, 3 hp - up to 18 acfm if I was to upgrade the motor). The others are all around 10 - 11 scfm @ 90 PSI. I understand the difference in ACFM vs SCFM and at my location/use conditions, they are virtually the same. My question is the different rating pressures. Can I expect that 8.28 acfm @ 175 psi would equal 16.1 acfm at 90 psi (8.28 * 175/90)? I should remember this from school, but Mr Bernoulie left my brain a long time ago!

Bottom line, I know the Quincy is a better quality unit, but it is also 50 years old and I don't know the service history. The others would be new with warrantee - but of course lesser quality. I don't mind and even prefer old iron, but just not sure on this one.

Suggestions? Something I haven't looked at? Thanks for any advice anyone can provide.

Jon Hunter

payton · Mar 9, 2010

8 Gallon Electric Portable Unit

can you build your own? is so, for ~ 500 you can get a 18cfm compressor by buying a bare pump from eaton and improvising a tank from a old lpg tank or going tankless.

Payton

Mace Canute · Mar 9, 2010

They still build the Quincy QR-25 model 325. Considering the quality and the availability of parts, I'd buy it and fix what needs fixing and have a compressor that would be good for another 50 years. The fact they still make that model speaks volumes about the quality of machine.

moeh1 · Mar 9, 2010

Check with you local Quincy dealer. ask what they would do for an overhaul and/or rebuild and what they would charge. I just rebuilt a smaller quincy for my son, lcoal dealer got me the whole manual and parts list for it, plus alot of good recos on what to look for and what to do. Rings and cylinder were in good shape, so just valves, springs and new head gasket - about $25 all in. The quincy will still be running 50 years from now in my opinion. The newer high speed compressors generate more heat and don't have the longevity the old ones do IMO.
Good Luck.

medbug · Mar 14, 2010

The Quincy is the better choice. I work on breathing air compressors up to 6000 psi, and the key to compressor life is the rpm's at which it turns. Most of the compressors at the large box stores turn at 3500+ rpm's in order to gain the scfms listed on their output, which in turn causes lots of heat, so you will get a shorter life from the compressor block. Remember "Go slow Go long" "Go fast won't last"

DuckHunterJon · Mar 15, 2010

Thanks to everyone for the advice. I did purchase the Quincy. It's a 1968, QR-25, model 325 pump on a Gilbarco tank (need to measure, looks to be 80 - 100 gallon). It looks to be in good shape, wired it up, turned it on, found it leaked at the drain on the bottom. Looked closer, it has an auto drain plumbed in, with a couple of shutoff valves, and other misc fittings. One of the fittings was cracked (I may have done it when moving it). Running today to get a couple of new fittings, and do a full pressure test. Have to admit, running it up to 175 psi on that big of a tank for the first time has me a little nervous.

Assuming all goes well, next decision will be whether to take it apart and paint it, or use it as is. We'll see, I really don't need another project, but it would be a fun exercise. If I pull it apart, I'll probably go through the valves and what not to ensure everything is up to snuff while I'm at it.

It does sound sweet - thumpa, thumpa, thumpa at 380 rpm's!

Here's a quick pic of the wife on the tractor bringing it into the shop. I'll get some better pics and post them as I have a question about the single unloader tower (every other QR-25 I have seen has two).

Thanks again.

Jon