fridge powered compressor

[Gas mark 5]

Hi all!

Does anyone know anything about turning fridge compressors into useful compressors for powering tools from?
I managed to salvage a compressor from an old fridge and got it to run all right now (after spraying freon and nasty fluorescent blue oil all over myself ). Does anyone know what sort of pressure they can pump to, what sort and where to find a reservoir tank, if they would be suitable anyway, if they need any maintenance, or any information at all really
Thanks in advance!

 

[shenion]

They will work but are very low CFM (probably less then 1 CFM).

They should be good to a 150PSI. They are cooled by the freon. I have seen people cut the tops off an install a fan. Still I would not expect it to last as they circulate oil with the freon.

Would not be worth the effort IMHO.

 

[rtbcomp]

You'll wish you'd never asked!

This is my setup:-

http://forums.lr4x4.com/index.php?showtopic=9710

10 bar is easy peasey. The biggest problem is starting from cold, and as Shenion says, very low CFM.

The oil isn't circulated, the motor & pump sit in bath of oil.

 

[snowcat]

Gas Mark, I wouldn't advertise the fact you've vented a fridge full of refrigerant, The EA takes a very dim view of it, and anyone handling it without a CITB, trust me they will and have slapped large fines on violators..

 

[rtbcomp]

Gas Mark, I wouldn't advertise the fact you've vented a fridge full of refrigerant, The EA takes a very dim view of it, and anyone handling it without a CITB, trust me they will and have slapped large fines on violators..

The trick is to find ones that are already de-gassed. I got mine off Freecycle, they crop up where people have tried to de-frost them with boiling water and so-on. They sometimes appear in your local neighbourhood layby, the pipework can be damaged when they're thrown off the back of a van.

I was told of a firm near me that does the job properly and a search for your local WEEE operator may povide a supplier.

 

[Gas mark 5]

Oh dear, I didn't really vent it wink wink.
Whats wrong with it, is it a safty issue or an environmental issue?
I know that they used to use CFC's for the coolant, and that that was bad for the environment, but I thought that they had changed the law now...?
well...sorry...
Also, 150 Psi sounds good, axminsters best gets about 140 sumat i think... 10 bar, I know what that means as well! But CFM? Is that to do with the flow rate? I wouldn't imagine that I would need a high one if I had a reservoir tank...?
Thanks for all the quick replies!

 

[rtbcomp]

CFC's cause the hole in the ozone layer. There are CFCs in the foam insulation (as well as the refrigerent) which is why scrappies won't take fridge carcasses. Pikeys burn the foam off, but they're above the law. The last I heard is that the hole is beginning to heal up.

CFM = Cubic Feet per Minute.

Nip into your local Machine Mart, their Shhhhhh range of compressors uses Freezer motors, you'll get some idea of the cfm from those. They limit the pressure to allow the motor to start under pressure, they don't use the dump valve in the pressure switch.

Someone on here left a fridge motor running overnight and it broke the needle on the pressure gauge, well over 200 psi we think.

 

[eil]

To start what does the rating plate/sticker say on the compressor ?
Let us know that and ill tell you its power and cc s
Has it got a start capacitor on it ? did it come off a freezer or a refrigerator?
yes you can use it to pump up your reciver, but you must put a oil trap in your line and re charge the compressor with what you have lost, most recip compa throw out oil (unless its a oil-less one which would not be on a fridge/freezer) made one out of two semi-hermetics and two old calor bottles a long time ago when air comps werent as cheap

 

[rtbcomp]

....... but you must put a oil trap in your line and re charge the compressor with what you have lost, most recip compa throw out oil ..

Absolutley - the air is filthy.

In the link above I describe a method of extending the air inlet outside the unit to get cleaner air, but it's not worth the hassle. I put more oil in the compressor than originally used, it lasts a suprisingly long time, I check once a month and I run these units several hours per day ay 100% duty cycle.

 

[snowcat]

Oh dear, I didn't really vent it wink wink.
Whats wrong with it, is it a safty issue or an environmental issue?
I know that they used to use CFC's for the coolant, and that that was bad for the environment, but I thought that they had changed the law now...?
well...sorry...
Also, 150 Psi sounds good, axminsters best gets about 140 sumat i think... 10 bar, I know what that means as well! But CFM? Is that to do with the flow rate? I wouldn't imagine that I would need a high one if I had a reservoir tank...?
Thanks for all the quick replies!

no apologies needed, was just pointing it out, being a public forum yep the brief answer is what RB said/ the long answer involves all kinds of boll*ks about HFCS/ODP some agreement that Iv now forgot on etc...Im not going to bore you with it..

 

[eil]

Bad idea rtbcomp it tells you how much oil should be in it and no more. because it could slug into the cylinder and cause it to "hydraulic" and bang goes your con rod

 

[runnach]

Emmmmmmmmmm, will it still keep the beer cool??

 

[rtbcomp]

Bad idea rtbcomp it tells you how much oil should be in it and no more. because it could slug into the cylinder and cause it to "hydraulic" and bang goes your con rod

Not in practice. I set the oil level to lowest stub, with a bit of clear pipe to check the level. The inlet is right at the top and I angle the pump so the inlet is pointing slightly downwards.

Pics here near the bottom and following pages

http://www.flickr.com/photos/rtbcomp/page2/

 

[eil]

All im saying rtbcomp is carefull. the main cause of failiure when they are on a refrig system is liquidfloodback when the pot has too much liquid in it then they go pop.
looking on your pics do you have trouble with the ones overheating in the micowave cabinet, because some of these compressors are fan cooled and some static cooling

 

[rtbcomp]

......
looking on your pics do you have trouble with the ones overheating in the micowave cabinet, because some of these compressors are fan cooled and some static cooling

On a hot day it smells a bit hot-oily so I open the door.about an inch.

On the next one I build I reckon I'll remove more of the metalwork from inside the cabinet and re-position the fan.

I'm also considering fitting larger unions so I can circulate the hot oil through the heating coil of a hot water tank to get free hot water.

Yet another configuration would be to remove the compressors from their housing and place several of them in a sump, the ones that start first will heat the oil so the others will start earlier.

It's been running almost daily for the last 12 months, the only problems I've had are seizures due to me not checking the oil (expected!) and a solenoid valve blocked up due to oily emulsion in the air, revised pipe layout should stop that.

One thing that did surprise me is that non of the thermal cutouts have failed, they work very hard when starting from cold.

 

[Luke]

Someone on here left a fridge motor running overnight and it broke the needle on the pressure gauge, well over 200 psi we think.

Erm......

Yes, they will pump to a very decent pressure.

FWIW, I have just one pump, and use it to fill a 300L tank. I run it pretty much every other time i'm in the workshop to maintain a reserve of 50 - 60 PSI, at this pressure the leaks 'cost' less air. If i anticipate using a lot of air (air tool like impact gun, air ratchet etc) I turn the compressor on as the kettle is boiling for the first time that day. After breakfast, cuppa, getting down to the workshop, sorting what i'm doing etc, the tank is well on its way to 100 - 110 PSI.

I find the low duty cycle, high demand use that goes with air tools is pretty well balanced by the 100% duty cycle low supply of the compressor. I will get round to adding another pump or two, at some point.

The copper plumbing i've used for a manifold does a good job of condensing the moisture out of the air, the water trap at the regulator hardly ever gets any droplets in it. I've not tried spraying yet but will look at a proper filter for that.

I've got a pressure relief/dump valve fitted now, btw!

 

[reedx]

Does anyone know anything about turning fridge compressors into useful compressors for powering tools from?

This link might give you some ideas

http://www.clubhyper.com/reference/compressorgi_1.htm

Colin

 

[Gas mark 5]

ooh! thanks for all the replies!
eil - the sticker say's on it;
"turk elektrik
AZ 68 T
230V - 50 Hz-1Ph
LRA:8.45 LBP R-134a S
26-07 0284826 F19"
I don't know if this makes any sense to you?
It has got a capacitor on it, and it came out of a refrigerator, just a litttle one.
When I run it no oil comes out, but the air smells, so is it in droplets to small to see or what? And could someone go into a bit more detail about how to make an oil trap? Do you just need a spongy type thing between the compressor and the tank or is there more to it than that?
oh and thanks for those sites reedx and rbtcomp
cheers!

 

[rtbcomp]

It's probably oil vapour, the oil is a special type and tends to be thin and smelly.

Oil traps are cheap enough from the likes of Machine Mart, Thorite &c. You only need a small one with1/4 in unions. Most of my oil & water just collects in the bottom of the receiver.

 

[eil]

Heres some info on that compressor

http://www.tee.com.tr/p_copm_r134a_comp_pd.php

3.59 cc
LRA locked rotor amps-current it takes to start it 8.45Amp
LBP low back pressure which means it cant start against any pressure on the discharge side
R134a is the gas its designed to work with. which means its got the poe synthetic oil thats verry hygroscopic
the capacitor is a run capacitor

I bet this came off a BEKO fridge
eil