Homemade Air Compressor

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Andre

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What happens when you find a junk 125 PSI 3 gallon compressor off the side of the road and mix in some scrap parts from a refrigeration unit? You get this!

The compressor is from a dehumidifier, and it's wired into the factory pressure cutoff switch. It can not only compress air, but it can also pull a mighty vacuum if I were to make a special fitting for the intake. I do need to add a regulator and a check valve because sometimes air creeps past the pump and leaks out the intake, but those are future additions. I had to make a new fitting to adapt two line sizes, but that didn't take long and I already had the compression fitting pieces.

Picture Gallery: http://imgur.com/a/FVf67

Video showing how quiet it is coming shortly. You could hear a church mouse sleeping over it once it hits 20 PSI or so.
 
Last edited by a moderator:
It appears pictures aren't working, but here is the video of it running. I'll upload photos from a different source soon.

 
Pics worked fine for me. Compressionstein!

Sent from somewhere in East Texas by Jake Parker!
 
Pictures shows up in tapa talk but not on a pc.
 
I used to do a bit of refrig work, so here's 2cents
1) any ref-a/c compressor will build up a LOT of pressure (300 plus) if you allow it, but the volume of compressed air is very small
2) they operate with oil circulating thru the system with the refrigerant, and that's what lubricates everything...most oil is in the bottom of the "dome" at rest
3) having an air tank full of high pressure air AND combustible oil could wind up being an explosion :>(
4) they do make excellent vacuum pumps and u can use any one thrown away...when it craps ..get another
I have two around here for that
OK that was 4cents
 
juiceclone said:
I used to do a bit of refrig work, so here's 2cents
1) any ref-a/c compressor will build up a LOT of pressure (300 plus) if you allow it, but the volume of compressed air is very small
2) they operate with oil circulating thru the system with the refrigerant, and that's what lubricates everything...most oil is in the bottom of the "dome" at rest
3) having an air tank full of high pressure air AND combustible oil could wind up being an explosion :>(
4) they do make excellent vacuum pumps and u can use any one thrown away...when it craps ..get another
I have two around here for that
OK that was 4cents
Click to expand...
you are correct
fixit
 
On #3, All oil lubricated compressors leak oil into the system, the pressures in a typical shop air system are too low to cause the oil to combust.
 
Not the same. Ref compressors do not have a separate "sump" for the oil. There is no "crankcase" The con rod and the motor itself, splashes oil to lube everything, piston, cylinder, reed valves, motor bearings in the same space that the piston draws air from on "intake". Some of the oil normally gets drawn in and takes a trip thru the system and winds up back in the dome. If used as an air compressor with a tank, that oil, and probably most of the oil will eventually wind up in the bottom of the air tank.

found this look inside =

The larger a/c or walk in cooler size comps do have a separate crankcase, but even those don't supply much volume of air.
 
Although you make a very good point about the oil, I do not notice any oil floating on the water from the tank drain or any oily air tool exhausts.
When I was figuring out of the pump worked I accidentally knocked the pump over and some oil spilled out. I determined it was either mineral or silicone based oil, I forget. Mineral oil has flash point of 320F, and silicone oil even higher. I am not able to find auto-ignition temps on mineral oil, but on silicone oil it's around 842F. This pump is thermally protected, and I have witnessed it shut off after a few fill ups in rapid succession (using a nail gun) and it did indeed shut off. The compressor housing wasn't too hot to touch, so I do not believe any internal part reached over 300 degrees F.

Thank you for your concern.
 
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