DIY Silent Compressor

[mayday0017]

I have seen several pictures and videos of people taking old refridgerator compressors and turning them into air compressors. Some people have taken them and added them to a tank and others use them as is.

Has anyone on here ever done it? How effective are they?

Awhile back I came across a company that makes compressors with what appears to be this same concept. They are pretty much silent units....

Could you just buy several new refridgerator compressors for roughly $40 ea and toss them on a tank from and old compressor and have a nice quiet setup? The other nice thing, would be if you need more CFM as you expand your work needs you can just buy more compressors to add to the system....

This is all just an idea I have kicked around and figured I would bring it up on here. By doing this maybe I'll build one at some point, or maybe I'll find out it is not such a great idea after all and save myself some money and effort.

DIY example

Commercial example (sorry for size)

 

[gordon_gjs]

Subscribed!

I would love to see some examples. I have a broken fridge at the house that I am about to get rid off, maybe I could save some parts for this.

 

[pipsters]

To do it right you need an air/oil separator with return. Scroll compressors like the above use oil in the refrigerant (or air) to lubricate the pump. That is party why rotary air compressors so are expensive - they have many more intricate systems to them.

For the compressor above it puts out 5-6 CFM @ 70 psi.

That's pretty weak IMO.

 

[mrpizza]

That isn't much air, I have the 60 gallon Husky that puts out right around 11 cfm @ 90 psi, and I give it one hell of a workout with an air cutter and other tools.

 

[mayday0017]

I do agree that is not enough CFM, I just know you can buy a LOT of refriderator compressors if you watch for them for dirt cheap. Also with a standard 17cfm 80gal compressor costing $600+ you could buy several of these compressors. The footprint would be much bigger, but man a totally quiet system, that would require little to no maintaince for years.... OH and if you do have a problem it will be with 1 compressor so the system will keep running until you have time to fix or replace the one unit.

All that being said, you might be right and this might be some monster of a thing that takes 30 compressors to make anything close to useful....

 

[DHCrocks]

how would you know if one compressor goes down? looks like they are all piping into a singular manifold. I guess you could put a pressure gauge on each compressor output and then a check valve then pipe to a manifold but that seems like a lot of stuff and money. would look bad *** though.

 

[KinzeMech]

That would be very quiet. It would also be very low output.

Keeping the compressor lubricated is going to be a problem. In it's original application, those sort of compressors have lubricant mixed in with the refrigerant stream, much the same way as 2 cycle engines having oil mixed in the fuel.

If that compressor is able to achieve a meaningful level of output, you will need a more sturdy pressure line. Single stage compressors routinely reach 500 degrees output temperature, the hose you are using from the compressor to the tank does not look like something that will handle heat.

 

[honcho]

fridge compressors are better for use as vacuum pumps to evacuate ac systems! Slow but quiet

 

[TireTracks]

They would work fine, as a replacement for small air compressors, Think 5-15 gallon compressor sized one. it would work great for nail guns/Blowing up tires/ air brushing/etc.

But it would not be a good replacemet for a 80gallon 2 stage that puts out 30cfm at 175psi.

 

[PT Doc]

How quiet would you speculate that these would be?

 

[rwhite692]

A colossal waste of time and money. Even if you had (given your example) four, $40 compressors ($160 spent before even getting them configured onto a tank!) when you got it up and running you would not have even half of the CFM that you can get out of a commonly available pancake or mini-hotdog compressor, that you can buy everywhere for under $80.

 

[TireTracks]

A colossal waste of time and money. Even if you had (given your example) four, $40 compressors ($160 spent before even getting them configured onto a tank!) when you got it up and running you would not have even half of the CFM that you can get out of a commonly available pancake or mini-hotdog compressor, that you can buy everywhere for under $80.

These would have a huge advantage, your neighbors would not be out in a mob with pitchforks and torches like they would be if you fire up one of the cheap oil-less pancakes in the middle of the night.

I don't understand why anyone would use that plastic hose for one though, those little compressors can put out a few hundred psi. You'll blow those hoses right off.

How quiet would you speculate that these would be?

I'd say that it would just be as quiet as your fridge is, just a low hum noise.

 

[Gary S]

A colossal waste of time and money. Even if you had (given your example) four, $40 compressors ($160 spent before even getting them configured onto a tank!) when you got it up and running you would not have even half of the CFM that you can get out of a commonly available pancake or mini-hotdog compressor, that you can buy everywhere for under $80.

I agree totally. That link shows 7.06cfm from 4 compressors. So, you get 1.765cfm from a single compressor. That isn't worth starting up.
10 of them would make a nice amount of air. 20 of them would be serious air.
So, scrap 10-20 refrigerators and spend the bucks to get where a single decent compressor will get you...................Uh, NO!

 

[kursplat]

I agree totally. That link shows 7.06cfm from 4 compressors. So, you get 1.765cfm from a single compressor. That isn't worth starting up.
10 of them would make a nice amount of air. 20 of them would be serious air.
So, scrap 10-20 refrigerators and spend the bucks to get where a single decent compressor will get you...................Uh, NO!

would you want the load of 10 to 20 fridges running all day while your working in the garage?

 

[KinzeMech]

It's worth noting, you may need to plumb in some sort of unloader valve. Those types of compressors are not usually able to start against a load. Normally, by the time a compressor cycles back on, there has been time for pressures to equalize. Without that, I think the compressor would stall.

 

[Displaced Hokie]

Glad to see at least a few open minded posters. No one expects something like this to perform like a traditional compressor. But, there is a real use for these when working late at night or in your basement (with the S/O upstairs).

 

[timbitca]

This would be perfect for here at school!

We just have an in-car compressor to blow up soccer/basketball/volleyball/etc balls... it isn't too bad when you only have to do 1 ball, but when you're doing 30-40, it get's pretty freaking annoying on the ears...

 

[SpeedyGee]

I've had one running in my garage for over a year now. It has two HBP (High Back Pressure) freezer compressors, outputs nearly 5 CFM. I do all manner of work with the compressor. The only thing it has ever come unstuck on is removing a crank pulley bolt. For everything else it has worked a treat. For what I do 5CFM is plenty but if I needed to I could beef it up some more.

If your constantly using air tools then you need to look at a proper compressor but for occasional use it great, it works for me and of course great for the neighbours.

 

[StaggeringGoat]

They would work fine, as a replacement for small air compressors, Think 5-15 gallon compressor sized one. it would work great for nail guns/Blowing up tires/ air brushing/etc.

But it would not be a good replacemet for a 80gallon 2 stage that puts out 30cfm at 175psi.

This. I used a compressor that I pulled out of a 5k BTU air conditioner for a while. Same amount of noise as a fridge. Also puts out very high pressure. I had mine attached to a propane tank and pumped it up to about 300 PSI. Not a huge amount of CFM but still useful. Also used it as a vacuum pump.

The compressor locked up after a few years use, but I never attempted to oil it, and it was WELL used before I started. I'd like to try it again with the compressor out of a large heat pump, should pump more air.

 

[TireTracks]

This. I used a compressor that I pulled out of a 5k BTU air conditioner for a while. Same amount of noise as a fridge. Also puts out very high pressure. I had mine attached to a propane tank and pumped it up to about 300 PSI. Not a huge amount of CFM but still useful. Also used it as a vacuum pump.

The compressor locked up after a few years use, but I never attempted to oil it, and it was WELL used before I started. I'd like to try it again with the compressor out of a large heat pump, should pump more air.

I can't give numbers, but the big A/c or commercial fridge/ freezer compressors put out alot of flow. We had a few reciperocateing pumps at school that had pistons just as large as a normal Air compressor pump.

Your heatpump/AC is piped with pipe between 1/2" and 1~". Thats alot of flow at a few hundred PSI. New R-410 systems can run way up over 500psi, so these pumps arnt weaklings.

The Compressor in the first pic, probably has a piston roughly the size of a quarter, with mabey 1"stroke.

 

[KinzeMech]

It's worth mentioning, compressors from window AC units will be much more powerful than refrigerator compressors. Probably on the order of 2-3x or better.

 

[Mandres]

I've had one running in my garage for over a year now. It has two HBP (High Back Pressure) freezer compressors, outputs nearly 5 CFM. I do all manner of work with the compressor. The only thing it has ever come unstuck on is removing a crank pulley bolt. For everything else it has worked a treat. For what I do 5CFM is plenty but if I needed to I could beef it up some more.

If your constantly using air tools then you need to look at a proper compressor but for occasional use it great, it works for me and of course great for the neighbours.

Cool, do you have any pics? How did you address the lubrication issue? Do they work with a standard pressure switch (assuming you have it plumbed to a tank)?

I would love to set up one of these to use indoors.

 

[jake1.11]

Bump...I'm normally a lurker, but this was an interesting thread. I too was wondering about the details on SpeedyGee's set-up...

Jake

 

[FIFTY2]

Im gonna bump this to see if anyone has used a large compressor from an AC condenser. My pump went out last week. Im going to try using a 5 Ton ac compressor. I wonder if you can convert btu to cfm? 60,000 btu....?

 

[Outlawmws]

Im gonna bump this to see if anyone has used a large compressor from an AC condenser. My pump went out last week. Im going to try using a 5 Ton ac compressor. I wonder if you can convert btu to cfm? 60,000 btu....?

BTU has nothing to do with CFM.


You need to know the bore and stroke, (or CI displacement) and the normal running RPM's and you can calculate the CFM (After calculating the CIM...)

 

[FIFTY2]

Can't find any info on ci for a scroll compressor,(obviously there is no bore and stroke)
I can look in one of my reference books for displacement of a hermetic recip 60k btu and work from there....

http://www.traditionaloven.com/tutorials/power/convert-btu-per-hour-to-atm-cfm-atmosphere.html

 

[larryq]

This may be of interest to anyone looking to build one, at least in a more manageable size.

http://jason-jones.com/hobbies/airbrushing/110-diy-mini-silent-compressor.html

 

[kerimil]

Hi,
I've modified quite a lot of fridge compressors into DIY silent air compressors, so if you have any questions feel free to ask.

I often get questions on wiring them etc. so I created a couple of videos on the topic. Hope you find them useful.
<iframe width="853" height="480" src="//www.youtube.com/embed/BfAC05eYGHs?rel=0" frameborder="0" allowfullscreen></iframe>

<iframe width="853" height="480" src="//www.youtube.com/embed/5LvTdvyIFyg?rel=0" frameborder="0" allowfullscreen></iframe>

<iframe width="853" height="480" src="//www.youtube.com/embed/k08kYVoXZrQ?rel=0" frameborder="0" allowfullscreen></iframe>

....and here is a simple homemade compression fitting I came up with - it makes it a lot easier to service the compressor than brazing and other permanent methods
<iframe width="853" height="480" src="//www.youtube.com/embed/NRrOWQEFalQ?rel=0" frameborder="0" allowfullscreen></iframe>

Though if think you really need my help and you can't find answers in the videos just write a comment on YT (Mind you that if you're asking for help with wiring etc. please include pictures of your setup and write down any model numbers from your unit. I don't have magical powers and I don't know what compressor model you have and/or whether it has all the parts that it should have when you got it)

 

[Sparkums]

BTU has nothing to do with CFM.


You need to know the bore and stroke, (or CI displacement) and the normal running RPM's and you can calculate the CFM (After calculating the CIM...)

Outlaw,

Wondering what kind of CFM I might get out of this unit CR18K6E-PFV-875(New in Box)?
2 Cylinder, Bore 1.52, Stroke .52, RPM ???

I looked at the spec and can't find the RPM, but I'm guessing it depends on V setup? I've got a nice 30 gal tank, not looking to sandblast or booth spray or anything. Should I sell it, if yes, and use what?

Awesome thread!

 

[Outlawmws]

Outlaw,

Wondering what kind of CFM I might get out of this unit CR18K6E-PFV-875(New in Box)?
2 Cylinder, Bore 1.52, Stroke .52, RPM ???

I looked at the spec and can't find the RPM, but I'm guessing it depends on V setup? I've got a nice 30 gal tank, not looking to sandblast or booth spray or anything. Should I sell it, if yes, and use what?

Awesome thread!

Need the motor's RPM and the pulley sizes at both ends (unless they are identical, never seem that on a comp)

 

[Danglerb]

Outlaw,

Wondering what kind of CFM I might get out of this unit CR18K6E-PFV-875(New in Box)?
2 Cylinder, Bore 1.52, Stroke .52, RPM ???

I looked at the spec and can't find the RPM, but I'm guessing it depends on V setup? I've got a nice 30 gal tank, not looking to sandblast or booth spray or anything. Should I sell it, if yes, and use what?

Awesome thread!

There is one on ebay right now for $600, its a big commercial unit, 220v, and will never work as well as a real compressor you could buy for half of what it should sell for.

 

[u3b3rg33k]

Lol thread resurrection!

I have a california air tools compressor. It's amazingly quiet (has cooling, doesn't have oiling issues, and is rebuildable - not hermetically sealed). and it also builds usable pressure - If i ever have a need for a real one I'll consider that Eastwood scroll, but for popping off lug nuts/filling tires it works just fine.