Champion VR5-8 Compressor

[dgrall]

I am a relatively new member to this site and am extremely greatful that I found it. I am looking at a used Champion VR5-8 Compressor and was hoping to get some insight from forum members. It is currently has a 3 phase motor on it and I will either replace it with a single phase or buy a VFD. Does anyone have any experience with using a VFD on a compressor? What should I expect to pay for this compressor in working order? It is approximately 10-15 years old.
Thanks
Doug

 

[930dreamer]

I always post this;

Can you listen to it operate, does it build to the proper pressure and shut off? Not sure on a vfd and a compressor, the compressor will be a hard start item, might need more than 3 hp on the vfd.

 

[zkling]

I am a relatively new member to this site and am extremely grateful that I found it.

Well first off. Welcome

As for your compressor. Unless you can get it really cheap I would personally pass on it. Putting a VFD on a compressor is typically a very expensive procedure unless you have a supply of cheap VFD's. Issues is large hp vfd's like needed for a compressor of that size (~5hp) can be not only hard to find, but very expensive at that.

Your better option would probably be to find a used single phase motor of appropriate HP and swap it out. Unfortunately as with VFD's larger hp single phase motors can be hard to locate at a low price.

Do you know the history of the compressor? I wouldn't buy a compressor that you can see run like 930 detailed above. If you can't see it run, then assume that pump is shot and price accordingly. Typically you can find a good compressor for ~$500 so sinking money into a worn out compressor tends to not be the best option.

As for price, well it kinda depends on your local market. Where are you buying it from? The fact that it is 3 phase will go in your favor as most small home shops don't want to fool with 3 phase compressors. Which would also make me wonder where it is coming from. Possibly an industrial place that used it hard?

That is a good high quality compressor and should provide years of service granted it is not already worn beyond its limit.

 

[dgrall]

Thanks for the input! I will be going to look at it Monday. I have determined that it is was built in 2004. It was used in a car wash. I will evaluate it based on 930's criteria. I recognize that it must be purchased for a reasonable price. I am not afraid of a rebuild if the price is right. The VFD conversion intrigues me because of some of the efficiencies that might be achieved as a result.

 

[930dreamer]

Thanks for the input! I will be going to look at it Monday. I have determined that it is was built in 2004. It was used in a car wash. I will evaluate it based on 930's criteria. I recognize that it must be purchased for a reasonable price. I am not afraid of a rebuild if the price is right. The VFD conversion intrigues me because of some of the efficiencies that might be achieved as a result.

This has some good information on vfd's and compressors.

http://www.practicalmachinist.com/v...rs-vfd/thanks-air-compressor-vfd-help-172103/

 

[dgrall]

Thanks for the link 930!

 

[Panel Dan]

To use a compressor like that on single phase you would need a 1ph electric motor, and a 1ph pressure switch. Using 220v single phase, you should be able to get a 5hp motor to turn. I would probably not bother with attempting to put a VFD on that compressor as it won't run enough for the efficiency benefits to be shown. The pressure switch should be fairly simple to install, but finding a suitable motor and power point might cause you problems.

If it is for your home workshop I can't imagine you needing the machine to idle down when you are using air tools. The machine will most likely be either running flat out while you use your impact wrench / spray gun / die grinder, or it will be switched off. The other thing is, the VFD won't make it any less noisy, and I'd reckon that machine would be a really loud banger of a compressor.

930 and zkling are dead right too, don't buy it unless it is in perfect working order. They aren't hard to fix, but some compressor parts are more expensive than buying a new compressor. I've had small machines like that that have basically been written off as the cost of a day's labour and workshop rate is higher than the cost of a new machine.

VFD screw compressors are fantastic things when you're talking about places like print shops, large auto repair facilities, factories and the like, but are kind of pointless in a home workshop.

That being said, if you can get a plug and play type inverter, then it opens the door for you to power other 3 phase machinery as well.

Good luck!

 

[dgrall]

Thanks for your insight Dan!

 

[dgrall]

I appreciate everyones input. The current owner continues to drop price but not quite where it needs to be for me to buy. I also have a lead on a Gardner Denver Value Plus 7.5 Hp that is single phase. Does anyone have any knowledge about the value plus series?

 

[scw1991]

I'd personally pass on a 3ph unit unless you got it dirt cheap. You can get a Baldor 5HP 230v/1ph motor for about $350 new. But you'll also have to pick up a definite purpose mag motor starter with thermal overload protection rated (NEMA 1-1/2) minimum for 5HP motor. This will run you another $100-$150.

 

[cwlo]

I purchased a 3ph Champion, and bought the single phase Baldor motor for $325. I was able to use the existing starter, as it can be configured for single phase. I also had to increase the wire size to the motor, as single phase uses more amps. Pretty straightforward, and easy. I paid $500 for the compressor, and it was hardly used.

Chris

 

[scw1991]

Chris,

Glad it worked out for you. I was concerned the starter might not be sized adequately for 1ph operation as there is a much less current draw on 3ph power. Looking forward to seeing some pics

 

[dgrall]

Thanks Chris!

 

[Panel Dan]

As a compressor technician, I have been trained to hate Gardner Denver. As far as reciprocating compressors go, most are identical in operation. They mostly run reed valves in and out of the heads, and mostly use a standardised pressure switch. GD screw compressors are a completely different story though. I'm not sure if they're a rebadged Compair, a rebadged Tamrotor, or a ******* child of it's own master, but from a technicians standpoint, and being from Australia, they are one of the worst machines I've had the pleasure of working on from ease of disassembly to access to spare parts. The spare parts supply may be better in other parts of the world, but the best automotive reference I can give is that they are like an Alfa Romeo without any of the fun bits. The company I worked for before the one I work for now were agents for GD and Tamrotor and my toolkit went from being fairly standard to having custom (read as: CUT UP) sockets, wrenches and ratchets, and a whole heap of tools I had to make myself. In all honesty, those machines made me look for a better job.
Sullair, Quincy, Atlas Copco and Kaeser are all better machines, and if you're including reciprocating machines, Ingersoll Rand are very good too (IR screw comps are a NIGHTMARE to work on.)
I suppose my advice is based more on the service and maintenance of machines that run flat out for at least 8 hours a day, but I always dreaded service calls to Compair, GD and Tamrotor machines as they seem to have been designed by someone who doesn't know which end of a hammer is the handle.

If you've got 7.5hp that you can run on singe phase, it might be worth looking to get a small screw compresor. They are quiet, generally pretty easy to maintain so long as the oil and filters are changed regularly, and (a bit or research will confirm this) mostly run 1ph control cirrcuits and just have 3ph running to the motor. It might be worth you looking into a rotary inverter to convert from 1ph to 3ph too... this is the wrong side of the planet, but something like this is almost certainly available.

All else I'd say is make sure you can see it running before you hand over any hard earned dollars.

 

[b-body-bob]

Sorry for re-using this thread, but I was given a Champion VR5-8 last night that seems to have eaten a bearing in the pump. It was popping breakers and has a nasty sound and feel at a certain point when rotating the pump by hand. It was apparently working OK (at a quick lube) until it got to where it wouldn't start. I'm looking for advice on where to find parts and possibly a manual to help with disassembly/reassembly. I appreciate any help if anyone has that info or ideas on what could be wrong.