Quincy Air Compressor Questions

[R12C]

So I have an opportunity to purchase a 1994 Quincy air compressor.  Person selling it bought it brand new in 1994.  I've been told it's dual stage, 60 gal, 5HP, single phase 220v.  I went and looked at it and I was a bit confused about a few things. First thing is the motor says 15 amps.  I'm not an electrician but I thought a motor of 5HP would be higher than that and require a 40 or 50 amp double breaker.  Owner says they used a 20 amp double and never had an issue.  Also, how the heck can you tell if it's truly a dual stage.  When I looked at it it wasn't connected to power so I couldn't hear it run or gain pressure.  Told them I wouldn't consider buying it until I could hear and see it in operation.  Phone call this evening told me it's hooked up and "running like a champ".  So what am I looking at here and what kind of price should I be expecting?


https://photos.app.goo.gl/u8RsKVkKbWcWp6qo8


https://photos.app.goo.gl/ffLDR8GioFxj9xbk8


https://photos.app.goo.gl/HgaNSLN1pfduPXXy7

[iamrfixit1966]

Doesn't look like a two stage but hard to tell with that picture. Looks more like a two cylinder, single stage compressor.

A two stage compressor will have a larger diameter first stage cylinder and a smaller diameter second stage cylinder. The first and second stages are connected together, using a finned cooling tube, then the second stage cylinder will discharge into the tank. You will be able to see that one piston is larger than the other by looking through the fins at the cylinder walls. Both of the cylinders can be contained in the same casting or they can be separated. Either way you'll clearly see a tube coming out of first stage and entering second stage. The finned tube is to help cool the air between stages. Two stage usually operates at 150-175 psi and is able to be run for longer periods without creating excessive heat.


That motor isn't a true 5hp, probably more around 3-3.5 hp. It probably "develops" or has a "maximum" of 5hp. Many tool manufacturers overrate their motors like that. That same 15 amp motor was installed on many single stage, 60 gallon compressors of many brands. A true 230v, 5HP motor would require well over 15 amps, think mine is 23 amp and runs on a 30 amp breaker.

[Mike in kc]

I agree with "1966"  It looks very much like my compressor from the same era.   I paid about three hundred twenty for it, new.

[R12C]

I think I'll go look at it again.  It does have two cylinders and they are sitting front to rear of each other, actually connected.  I guess the only way to determine if it's two stage is to look for the intercooler tube/fins.  I guess listening to it run may be the deciding factor.  The two stage is much quieter so I'll see how loud it is.  That's really the only reason why I want a two stage is because it's quieter.  Quincy does make compressor pumps where the two cylinders are directly side by side, just can't see it in this picture.  They also have the original instruction book but it's doesn't clearly state "2 stage".

Looks something like this.  

https://photos.app.goo.gl/w36mtxoUefmYuWfs7

[TDKPE]

What they said above. Notice the "HP" box has SPL in it (special), "Compressor Duty", and a relatively low locked-rotor current (LRA); it's not a 5 continuous hp motor, though any 3 hp or so motor will output (develop) 5 hp when overloaded ("Sears horsepower"). A very efficient 5 hp motor would be around 20A at 5 hp. Using the loosely reliable chestnut of 4 cfm per hp at 40 psi, that also maps to about 3 hp, if the other Quincy units with the same model number have reliable data.

Looks like a fine unit, but it's not 2-stage, and it's not 5 hp continuous output.

Oh, and do have the seller run it until the pressure switch shuts it off. I once had a dude run a compressor for less than a minute to demonstrate how well it ran, but when I insisted he run it to cut-off pressure, it wouldn't build pressure beyond a point. Hence the short demonstration. And no sale, as I didn't need another project.

Edited to add links:

http://machinerymax.com/Event/LotDetails/5427435
http://www.compressedairstore.com/151C60..._3249.html (rather suspect specs)

[loosetoe]

As others have said, I believe this is a single stage 3.5 hp unit.

From what I have seen, Quincy uses Baldor motors when going to 5hp and larger and uses century on the smaller motors. This may not have always been the case, but seems to be so on modern units.

I own a Quincy 2 stage 5hp of more modern build. The pump is SIGNIFICANTLY larger. Amp draw according to the build plate is 28 amps.

I believe the modern equivalent of this compressor is this unit:
https://m.northerntool.com/shop/tools/pr..._200612355

I am sure the unit is still a very good compressor assuming it is in fine working order, but it’s capabilities may have been a bit overstated.

[Just_Dave]

By the looks of it I suspect that the pump may be very similar to the Campbell Hausfeld compressor that I have from the mid 80's.  As I recall the marketing lead you to believe that it was a 2 stage but in fact it was a 2 cylinder or dual cylinder or dual pump?    When I figured out that it wasn't a true 2 stage I talked to a fellow at a one of the local tool places about them.  If I remember it correctly it used the 2 cylinders in series.  The theory was that it would recover faster.  I can honestly say that I have had no issues with mine other than the tank size is too small.  I have used it enough that if there was an issue with the concept I would have had problems by now.

[BloomingtonMike]

Its also is a 3450rpm motor and as such that compressor will be louder than a 1725 rpm motor driven vetsion. Also no mag starter is a bummer. Prob a reason its not their sig blue color.

Most likely a perfectly fine compresspr but should not command premium quincy money. Prob worth $250-$275 to me if perfect.