Screw Compressor Needing TLC

[pamike]

So I found a late model 5 HP Chicago Pneumatic Screw compressor/air dryer unit that needs some TLC. I called the guy and he said it quit working, they needed air so they went and bought a new one. All he knows is the motor wont turn... Make an offer... Its a CP CPN 5,5. Cant find much on the net about them...Educate me on screw compressors...Should I buy this for me hobby/farm shop?

 

[Streetbu]

I'd buy it. You have ti pretty m7ch guess its the motor or the pump. Hopefully the motor, but most likely the pump. Get a price on a replacement pump and also on the same unit brand new, subtract the two, then divide that answer by two and theres what i would offer.

 

[koditten]

Have you done any diagnostics? Whats it do or not do when you supply power? Breakers trip? Does it just sit there? Does the motor hum or buzz when powered?

If that is all the guy is going to give you for a description of the issue, then I would not be offering anything above scrap value for it.

With that said, screw compressors have their uses, but I don't think many of us home wrenchers could justify owning a screw drive compressor.

I maintain 8, 250 hp screw drive compressors, so I have an idea what they are good and not good for. I wouldn't have one for home use.

 

[pamike]

The guy isn't a technical guy by any means. He just said "I couldn't get the motor to turn over". He works for a business that owns it so I don't think he has any reason to be dishonest about it... He said he is looking for an offer in the "hundreds"...
I think this is a belt driven unit so I should be able to see if the screws will turn over by hand, right?
Whats the real downside of a screw unit? You basically turn them on and leave them on right? So they use more electric? I would only turn it on when I am in the shop and needing air...

 

[koditten]

Screw compressors supply a large volume of air at a set pressure. They would be great for running a sand blast hood. Turning the thing on to air up the tire on the mower, would be kind of over kill.

In most cases, the compressor is "on" the entire time compressed air is needed. I'm not sure about this unit. They can be quieter, so that is an asset.

I'm sorry, but any tool, in non running condition is not worth "$100's"

I admit, the curiosity factor has me intrigued, screw compressors are designed to run years, not hours continuously. What made this unit fail has me wondering.

I presently have machines that have run for 20 years continuously with nothing more than oil and separator changes.

 

[pamike]

You don't think a machine that is around 4k new is worth a couple hundred with an issue?I didn't think that was a bad price. If I could get it for $400, the tank and air dryer are worth that, don't you think?
What would your offer be?

 

[koditten]

If the screw is locked up, the repair won't be worth the money to fix it. A replacement screw will be very spendy.

I'm sorry, if I knew the issue was a control problem, then I would say go for it. If the motor or the screw is fubar, the cost to repair would be too much.

If you can get it for cheap and are looking for a cool project, then get it.

why don't you wait a week and see if it sells? Might be even cheaper next week.

 

[finn]

I'd price a screw assembly and a motor before I offered a nickel.

If parts cost a thousand dollars, I'd put that money towards a quality conventional compressor.

Less than $500, I'd offer a couple hundred, but no more.

You're buying a pig in a poke.

 

[pamike]

Are the motors on these something special? Are they a standard commercially available motor?

 

[EOC_Jason]

The smaller screw drives like that are pretty cool... Similar performance to a piston, just much, much quieter...

The few I've seen just have a regular TEFC motor in them, nothing custom or exotic.

It's single phase, so maybe it could just be a capacitor (are you that lucky?)... Or maybe the motor is completely dead from constant usage.

I would assume they did regular maintenance changing the oil. If not maybe a low-oil sensor is preventing it from turning on?

How much you want to offer I guess is based on how much risk you are willing to take and your future plans with it... $250 to me is a fair gamble. If it needs a new motor and you had to buy a specific one new then you would probably sink in another $250... If the screws are toast, I don't know if it would be worth fixing or not, you would have to price those with CP...

I don't know if you can try spinning it by hand, they are usually enclosed, so unless he already has it open or will let you spend a few minutes taking a panel off...

They have a 5 year warranty... Depending on when they bought it they might be able to get warranty repair? It has a 2011 mfg date...

 

[c39er]

It's made in italy...parts?

 

[EOC_Jason]

It's made in italy...parts?

A lot of air compressor pumps are made in Italy... (and highly desirable because of the quality)...

 

[54stude]

At work we have 7.5, 10, and 30 horse screw compressors. Beside them all being 3 phase, I do not imagine you would describe any of them as quieter than a piston compressor, just a different kind of sound.


Sent from my iPhone using Tapatalk

 

[LS6 Tommy]

All I could find:

http://www.cp.com/content/cp/pt-br/...ors/fixed-speed/CPN-3-20-HP-Screw-compressors

Tommy

 

[pamike]

All I could find:

http://www.cp.com/content/cp/pt-br/...ors/fixed-speed/CPN-3-20-HP-Screw-compressors

Tommy

Yeah, same with me...Kinda odd that there isn't more out there...no parts diagrams, no parts houses, no forums talking about them...
Makes you wonder if it was a short lived odd duck model or something..

 

[930dreamer]

These guys on YouTube have some good compressor videos.

 

[pamike]

So I went and checked out the compressor. The guy I talked to introduced me to the maintenance guy. He says the motor fried and they quoted him $1600 for a new motor. Claims a "solenoid in the motor blew up or something." Whatever that means...
The unit looks new, and has 2342 hrs on the meter. The motor and screw turned over smooth. I did notice some oil residue around the motor and in around the cover. I also really didn't see any oil in the sightglass at the end of the machine. There doesn't appear to be anything locked up...
Looks like its a 5 hp Weg motor...They told me to make an offer, but now they are thinking maybe $1500....hahaha...

 

[EOC_Jason]

Maybe tell them you are just a hobbyist and it would be for personal use and can't really justify spending a ton of money but can make them an honest offer of $X... and see where it goes from there.

Considering the age and the hours... That's like a little over an hour and a half of run time daily M-F...

It looks nice so you know it was well maintained. If it was beat up and coated in crud then I would pass without a second though.

 

[pamike]

Called the distributor that did warranty work on the machine. The compressor is a 230 volt machine but the plant is only 208 volt, so they fried the motor. Apparently a new motor was installed, and I think they continued to run the compressor and fried it again.
Kind of odd, because a 230 volt motor should run on +/-10% voltage, so 208 SHOULD be fine... Right??

 

[rlitman]

Called the distributor that did warranty work on the machine. The compressor is a 230 volt machine but the plant is only 208 volt, so they fried the motor. Apparently a new motor was installed, and I think they continued to run the compressor and fried it again.
Kind of odd, because a 230 volt motor should run on +/-10% voltage, so 208 SHOULD be fine... Right??

SHOULD work. But that is sure to shorten its lifetime. I don't get why they wouldn't just get a three phase unit if they have three phase power, but some people just don't get it.

 

[rlitman]

...I'm sorry, but any tool, in non running condition is not worth "$100's"...

So a truck with a flat tire is suddenly not worth hundreds? Come on.

I see more than several hundred dollars worth of stuff there. The tank alone has quite a bit of value. So does the refrigerated dryer.

 

[koditten]

I'm not thinking that is a real good comparison. You know how to get a tire fixed and how much it will cost. It was stated earlier that info on the thing is kinda scarce.

If you feel like a project, go ahead and get the thing.

 

[redmondjp]

Called the distributor that did warranty work on the machine. The compressor is a 230 volt machine but the plant is only 208 volt, so they fried the motor. Apparently a new motor was installed, and I think they continued to run the compressor and fried it again.
Kind of odd, because a 230 volt motor should run on +/-10% voltage, so 208 SHOULD be fine... Right??

If the motor was sized such that it was at or near its full-load amperage at 240V (so, motor a bit undersized), then it would not be happy at 208V. So that is a possibility. The other possibility is that something else is wrong with the unit which is causing excessive load on the motor.

 

[EOC_Jason]

Called the distributor that did warranty work on the machine. The compressor is a 230 volt machine but the plant is only 208 volt, so they fried the motor. Apparently a new motor was installed, and I think they continued to run the compressor and fried it again.
Kind of odd, because a 230 volt motor should run on +/-10% voltage, so 208 SHOULD be fine... Right??

Ehhh... That is really dicey depending on the quality of the motor and the load it is under. I would imagine they probably have even more of a drop in their facility with other big machinery going so you are just making a bad situation worse...

Good for you though as it sounds like their stupidity could be your gain assuming they will come down to a reasonable price.

Have you thought about how much you would want to pay? Realistically in your situation it wouldn't make sense to pay more for what a comparable new reciprocating compressor would cost.

 

[LS6 Tommy]

Called the distributor that did warranty work on the machine. The compressor is a 230 volt machine but the plant is only 208 volt, so they fried the motor. Apparently a new motor was installed, and I think they continued to run the compressor and fried it again.
Kind of odd, because a 230 volt motor should run on +/-10% voltage, so 208 SHOULD be fine... Right??

A 10% undervoltage results in roughly a 20% starting torque reduction and other not-so-good things. Not to be condescending, but 208VAC and 230VAC are not the same as 208/230VAC motors.

Tommy

 

[pamike]

A 10% undervoltage results in roughly a 20% starting torque reduction and other not-so-good things. Not to be condescending, but 208VAC and 230VAC are not the same as 208/230VAC motors.

Tommy

No insult taken! I am not an electrical guy. Can you explain? My understanding was the motors are good for +/- 10%, so a 230VAC motor (which this is) should in THEORY be fine at 208 VAC, right? I understand that with less voltage there will be more current. Are you saying there are motors made specifically to run either 208/230, and this one was only made for 230?

 

[LS6 Tommy]

No insult taken! I am not an electrical guy. Can you explain? My understanding was the motors are good for +/- 10%, so a 230VAC motor (which this is) should in THEORY be fine at 208 VAC, right? I understand that with less voltage there will be more current. Are you saying there are motors made specifically to run either 208/230, and this one was only made for 230?

Yes, your motor is specifically a 230VAC rated motor, but there are multiple voltage motors.


Tommy

 

[pamike]

Update: I left the guy a voicemail offering him $350 cash for it. I had found a guy that could remind the motor for $300 so I felt an offer of $350 was fair. The guy never returned my call and unit is still listed on craigslist.

 

[EOC_Jason]

He probably wants like $1,000+ or something for it...

Just save his number and check back in a month or two.... I'm sure eventually he will come down on price.

 

[PT Doc]

Pass unless you are ok with a large gamble. Let's say you pay $350 and get the motor rewound for $350. What if it still doesn't run? Why would they have been quoted $1600 to get a new motor installed? Just doesn't add up. You could be stuck owning a screw compressor with a new motor that doesn't run and then have almost $800 into it.

You can't be the only person that found it on cl and has been considering this purchase. Sounds like there is more to the problem.

 

[EOC_Jason]

If it's only a 5HP motor, I would think anything in a matching frame size & RPM should work just fine. Spending $300 to get the existing motor rewound doesn't make sense when you can find others cheaper... Especially if you watch CL or other surplus places... Heck, someone even got one on Amazon a while back for a steal...

 

[pamike]

It's a metric motor with odd high rpm. Probably also has a metric size shaft on it...

 

[ford33]

This is a gamble with little up-side benefit.

If you were able to buy it for$350 and added $300 for a rewind and were able to transport it home and if it works you have $650 into a machine with no warranty that provides little benefit over a piston style compressor in a home shop. If one other part is broken you could be looking at expensive repair parts and poor availability of those parts. Also, what do you know about maintaining a screw type compressor and how much would it cost you in time and parts to learn?

You could take that $650 and purchase a nice piston compressor that is known to work and will last 20+ years. Delivery, maintenance training and warranty included.

So why risk $650 on an highly speculative option when a low risk suitable option is available?

 

[pamike]

So the guy called me back after weeks and said its mine for $350 come get it...
I pulled the motor and dropped it at the motor shop. $250 later its good to go. Shop said the spring on the start winding switch broke and that cause overcurrent and it blew the capacitors. Hopefully I can drop the motor back in next week and button it up. Hopefully for $600 I will have a 5 HP screw compressor with air dryer that is like new....
Yeah, I know, maybe I should have just bought an old piston compressor but I like a project and a gamble...

 

[EOC_Jason]

Sweet! His loss is your gain! Keep us updated, and post pics!

 

[Todd.Brock]

Could this be the new Saylor Beal thread? I love a good compressor rebuild story. I have two or three of my own I have since decided it’s easier to take in lighter weight basket cases.

 

[CompressorPros.com]

That unit is older than what we have dealt with. If the airend is locked up, that would definitely be pricey. The motors are TEFC (totally enclosed, fan cooled) and are typically more than a standard ODP (Open Drip Proof) motor

With that model and serial number, [email protected] could help with parts identification and maybe a list price