Ac scroll compressor for air?

[Jduke]

I know there are several people that have used car ac compressors to compress air with varied success, and I’ve seen a few air compressors made from refrigerators.

I am fascinated by the idea of scroll compressors as found in some refrigeration devices, and am wondering how adaptable they are to compressing air?

I know that typically AC refrigerant has oil in it to keep the compressor lubricated, but I’m curious if that all that scroll compressors use, or if they are otherwise lubricated?

And if otherwise lubricated, is that enough to keep them from self destruction, or are they going to require lubricant in the air as well?

Has anyone used one for compressed air?

Thanks
Duke

 

[samss]

Heat will be a tough obstacle to overcome. Large scroll compressors have refrigerant injection just to cool the pump along with the returning cool refrigerant.

 

[Jduke]

The one I was looking at is a commercial unit with 7.5hp 3ph motor, by the time I got a vfd and dealt with oiling and cooling, it sounds like it may not be worth the effort

 

[Gunfixr]

I did it once. The ac had died, and I didn't much care, as it was a mud truck. I took out the rotary compressor and replaced it with an older piston ac compressor. Had to fab some bracketry. Worked good, but would slowly pump out the oil in the crankcase. I added some about every 1 to 1 1/2 yrs, using occasionally most days. I had mounted the reserve tank off a trailer above the rear axle of my f250, right in front of the rear fuel tank. I had an outlet/quick connect on either side midships, and a dump truck air horn up top of the cab. I had a pressure gauge in the floor between the seats, and a switch on the dash for the compressor clutch. So, I had to pay attention.
This was in the early 90s. At the time, the consensus was that the rotary compressors would not compress air.
Had it for over 10 yrs, sold the truck with it still in place.

 

[engineer2]

As gunfixr said, oil is an issue. Refrigeration compressors have some oil blowby, especially after lots of hours. Not a big deal in a refrigeration system where it gets recirculated. If you are compressing air, you will compress moisture into the oil as well. You have to separate the oil which is likely contaminated with moisture and you have to keep the compressor crankcase at the right level. People have converted the old Frigidaire A-6 compressors for air, but mind the oil!
https://www.pirate4x4.com/threads/a6-compressor-for-on-board-air.273104/

There are oil-free scroll compressors made for compressed air. That might be something to look into. Maybe Google scroll air compressor for vehicles.

 

[Gunfixr]

I think the one I used was an old frigidaire.
Yes, moisture would collect in the tank along with oil, and I'd drain it every so often.
I used straight 30 weight, non-detergent so it wouldn't foam up. The oil never got milky, so I wasn't getting moisture in the crankcase.

I looked those engine air compressors up recently. You better be sitting down.......

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