Anyone have experience using a frozen refrigerant can to recover refrigerant?

One could easily freeze a refrigerant can with a valve on it in water. The air conditioning system could be discharged into that can as long as it did not exceed 85% of the can's capacity. This would give the refrigerant room to expand when it warmed up.

Since R-12 is so expensive, it would better to recover it than to vent it.

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Even at 32F you have to pump it in with pressure for it all to condense. Pressure at 32F is ~25psi for R12, I believe. I've been wrong before FWIW. I use a refrigerator pump turned into a vacuum pump that according to others can be used at the outlet end to pressure fill an approved container (cylinder, rather than a can due to pressure) when evacuating an A/C system.

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

If you plan to use an empty disposable-type refrigerant container, be aware that they come with a one-way check-valve incorporated into the shut-off valve. They cannot be refilled. I think this was to prevent folks from converting them to air tanks, but would also prevent using them to recover freon either by condensing it or pumping it.

An empty bar-b-que type propane bottle is another matter. Adapters are available to hook them up to A/C fittings. They cost about $14 or so new, I think, at some discount places such as Sam's. Shops who sell blend-type refrigerants use these to send recovered refrigerants back to the manufacturer for reprocessing.

Special recovery refrigerant bottles are also available, but cost over $50. This is the type used with the recovery/recycling equipment at shops maintaining R12 and R134A equipment.

Good luck.

VeggiePup

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Dale
'67 Volvo 122
'79 Rabbit Diesel
'79 M-B 300TD
'82 M-B 300D
'83 M-B 300CD
'85 M-B 300TD
'86 Isuzu P'up TD
and a couple of Hondas

The newer mandated Propane canisters also have a valve which requires that you have something on it like your weed burner in order to get all the propane out... that did not used to be the case... you could just open the valve on the top to empty....
I did this the other day and took it to get it refilled... and when the guy weighed it he said it still had more than a lb in it...
So , from what yall said about propane/R12 contamination...... We should be careful to Power EVACUATE the RV canister before using it to catch any R12 we might need to save....

I would think that you would want to use the regular recovery cylinders so that you could sell it or whatever. This would leave your options open.

Good luck,

Thanks for the answers.

jbaj007,

The pressure of R12 at 32 degrees is 28.4 psig and R134a at 32 degrees is 27.8 psig. So, I would not be able to recover the whole system with out additional equipment. I think I would be able to recover the majority of the refrigerant anyway


The used R134a hand cans do not have check valves, so I could use those for storing refrigerant. I would have to use several cans.

Someday I will have to give this system a try.

Now getting back to your original question about a homemade recovery system. It seems that if you had an old compressor that was originally in an R12 unit of some sort, you could simply use it as a vacuum pump to pump refrigerant into a recovery cannister.

This is really all that the recovery units do, except they have an automatic controller that measures pressures and actuate some valves to do it automatically.

The thing is though, you will have to thoroughly evacuate the cannister before recovery and know when the cannister is full. You do not want to try to add refrigerant to a cannister that is over 80% filled. Also, you need to understand the pressures and times involved for seeing that there is no non condensable gas (air) in the cannister.

I would not try doing all this unless you have a THOROUGH understanding of the pressures and so forth. Without THOROUGH knowledge you would be an accident looking for the right time to happen. This is why the machines or so common.

Good luck,

Now temp compressors are the best as they have a habbit of being able to suck down nicely and tend to work at a higher pressur differance.

Second is small power usage is nice, easier on power bill and environment, so I look for mini-deep freeser compressors as usualy they range from 2~4 Amp.

I prefer to have the oil seps there to keep oil from going in or out of the compresser as wzrl said it is not needed despit how irrelivant it was to the design being showen, but for some one making one from scratch, He is indeed correct the intake oil sep is optional if you wont be using it to recycle, IE it will only be a recovery machine with out a large intake oil sep (There is a way around that taking vapour from the first tank holding the old recovered refrigerant and transfering it to a new tank, it achives the same job but you need another whole new tank! the unit I built I just drain the old oil ).

Condencer, any small condencer will do the job, fan of your choice, I pulled a nice litle unit that is forced air off a mide range R-134a fridge (It is going in V2.0 of my recovery unit only I will replace the fan to a 12V type), so keep an eye out for fridges they some times are handly, easpecialy the oil coolers off some of them.

on the discharge side try to keep the tubing as tiny as possibly so it doesn't hold a high volume of refrigerant (I origionaly planned on using all 1/8 for the discharge side, next one it will be this) This should help avoid mixing internaly when you need to recover a dif,, refrigerant.

For your waste oil you can use a ball valve or packless valve, just make sure they can with stand the max expected pressure on the low side, I used schraders on the high side though ball valves would have been much better.

Plumbing: What ever works best yet reduces any stress points and isolates any vibration. The coils you see on my system serve no other purpose other then to reduce vibration from the compressor.

Oil: POE is the best choise for us as it is compatible with all most every refrigerant a SS-Chiller builder/Moder will come accross barring a select fiew, for the ones it is not simply build a second to handle the ones with an oil that will be compatible.

Special Notes:
1- For a unit made to recover small systems an oil cooler isn't required but wont hurt the thing far as long working life is concerned, you just don't want the oil too cool! Passive and small will be more then enough.

2- For systems where it will never draw from a receiver or doesn't need to be a self contained recycling unit as well, an intake oil sep is compleatly optional, If it will be a recycling unit as well you need a tank which can draw liquid & Vapour (& at this point you need a oil cooling method)

3- Lower power is good all round for every thing concerned! A small 2Amp low temp, will do the job, no need to use a 20Hp compressor to recover 12oz of refrigerant!!

(Sod it they don't pay me enough to be perfectly ontime)

4- Pluming the oil drain, Nifty thing called gravity will do the work for you! all ways find the lowest point in the low side to place the drain, and then try and keep a slant going all the way out to the exit point (don't rely souly on the pressure within the system!

5- Over engineering never hurts, they did it with voyager and look how long it lasted, kept transmiting till it got out of range! So go ahead and use oil seps strainers and such, but try to keep it on the low side! We want the high side to have as little volume as we can!

6- Check valves are a nice thing to prevent odd things from happening, if you got one I'd throw it on the oil out line, as last thing we want is to back flush it!

7- Think of it like a SS only open ended, out goes into a tank, in goes through a F/D and to a system, we want it to be low powered as we can reliably get away with. know More about refrigerant recovery system