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Old 11-01-2014, 22:31   #1
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How to disconnect R-12 gas hoses from my engine driven fridge compressor?

I have to take my engine out for an overhaul. I cannot remove the engine driven fridge compressor from the engine, so I must disconnect it from the gas lines. Is there a proper way to do this? I could simply open the connections on the hose lines to the compressor and allow the gas to escape, but isn't it better to have a technician drain the gas first? It's R-12 gas. Also, isn't there oil which will leak out? If I cannot get someone to do it, can I do it myself? Any dangers involved? Can I potentially damage the compressor or other parts of the system? What can I do to prevent damage?
Thanks for any urgent replies (They are coming to get the engine in 2 days).
David
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Old 12-01-2014, 03:37   #2
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

If there are Rotolock valves on refrigerant lines at top of compressor refrigerant can be stored in system. Send picture of compressor and picture of refrigerant reciever. Generally compressor can be moved out of the way without disconnecting refrigerant hoses. It will be expensive and troublesome if refrigerant is recovered and put back in later.
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Old 12-01-2014, 11:40   #3
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

Hi Richard. Thanks for your quick reply. I will disconnect the hoses from the compressor tomorrow or the next day. I cannot get to the bolts holding the compressor to the engine. I believe the entire system was inserted into the tiny engine compartment together. I must disconnect the gas lines at the compressor, and later on, recharge the system. The compressor (Sanden SD7H15) originally had R134a in it, and that was changed to R-12, though Sanden says not to do so. I was in Vanuatu, and had no choice. In any case, the freezer ran fine on the R-12 for the last 3 years. I think maybe it's better to purge the old gas with a vacuum pump, and add R134a this time.
Do I need to worry about oil leaking out of the compressor when I disconnect the hoses? I was told to tape the holes on the compressor (and hoses?) to keep foreign particles and moisture out. Is this a reasonable plan? As I said, I have no choice, because the compressor bolts cannot be reached. Several people have looked at it and agreed. Do I need to do the low or high pressure hose first, or does it not matter?
Thanks,
David
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Old 12-01-2014, 11:45   #4
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

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ID:	73814I tried to add photos, Richard. I hope they appear.
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Old 12-01-2014, 11:50   #5
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

You need a tech to evacuate the R12, seal the system and I'd think replace the dryer and pull a good vacuum before reservicing.
Plus unless I'm mistaken R-12 and R-134A require different oils? PAG and PEG? Been a long time for me for R12.
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Old 12-01-2014, 11:57   #6
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

I think I gotcha. First vacuum out the R-12, then replace the dryer and vacuum again? If the oil was not changed when the R-12 was put in, then it should be okay, or should I replace that as well with new oil? On the compressor is written Oil: SP 10 or equivalent. Could you tell what type of valve it has?
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Old 12-01-2014, 12:01   #7
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

You need a tech, if nothing else you don't have the recovery equipment, I don't see any valves.
If you can leave the system intact and remove the compressor over to the side you'll be OK, otherwise in my opinion you need a tech, or it will become expensive, if nothing else you shouldn't let R12 escape, it's just not good.
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Old 12-01-2014, 12:30   #8
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

You don't just vacuum purge or release refrigerants in today's world the last I heard it could be a fine as high as $10,000 for doing so. An EPA certified tech with a recovery system IS required
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Old 12-01-2014, 12:33   #9
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

We don't know where he is, even though you shouldn't release R12, in some parts of the world there is no law against it. I assume he was in one of these places when he got the R12 charge to begin with.
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Old 12-01-2014, 13:37   #10
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

David, advice is correct that no one can work on his own refrigeration system unless he or she has a license and proper equipment. My guess is your Sanden compressor if manufactured after 1995 it would have had Ester oil in it which is compatible with both R12 and 134a refrigerants. Even if there is 134a in it the regulations prevent you from working on it.

Looking at pictures I see your problem. Is there any chance hoses could be disconnected at the other end? Small line is coming from seawater condenser and larger low pressure line is coming from either a suction line accumulator or return line from holding plates. One thing I see in picture is steel fitting at aluminum compressor fitting so you might break rear compressor casting if there is dissimilar metal corrosion there.

Refrigerant is always recovered from the suction side of system slowly to prevent loss of oil. Yes it is very important when a system is opened to the air to seal each opening, Zip-lock bags with rubber bands will keep moist air out.

Regardless of how much oil or what kind it is.
After compressor is removed from engine I would drain oil out through suction port and measure it. Then replace it with Ester (POE) conversion oil, with the same amount drained out Plus 2 ounces.

Engine driven systems with hoses generate moisture over time so very deep dehydration with vacuum pump requires special instructions. After system is all back together with new filter dryer e mail me for instructions or use vacuum pump instructions on my web site.
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Old 12-01-2014, 23:11   #11
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

Hi Richard,
I took these photos. Which one is the dryer, and which one the condenser? I think that the valve on the black cylinder is the one that the guy in Vanuatu used to vacuum out my old gas (Was it Isceon 40 and not R134a, or is Isceon another component?) Is this the valve that is either a Rotolock or Schrader?
Telephone calls are cheap from here in South Africa. May I call you?
Thanks so much,
David
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Old 13-01-2014, 02:23   #12
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

Please follow the smaller of the two pipes, its the HP, it should go to the condensor (it would be the second of 2 images, but check, before the condensor there should be a valve. There should be a valve on Suction side (Bigger pipe LP) follow that pipe as well. Without the 2 valves you cannot store the system gas. I do not know if you have Kollmanns instructions on pumping down. There is a trick to avoid moisture problem, you should preserve this gas until the refrig tech puts your system back together. If you have the option, get the technician to instal isolating valves and replace filter. Better if you have pipefittings to blank the ends.
I bow to Mr Kollmanns better knowledge and instruction, anything is better than letting that gas escape to the environment.
But in summary you must find those two valves, if you don't have them, I'd prefer you wait for refrig man.
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Old 20-01-2014, 10:33   #13
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

Is this the "Jipcho" Jim Young 40' from AK New Zealand?
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Old 20-01-2014, 12:31   #14
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

Yes it is. Who are you?
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Old 20-01-2014, 22:34   #15
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Re: How to disconnect R-12 gas hoses from my engine driven fridge compressor?

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Originally Posted by jipcho View Post
Yes it is. Who are you?
thought it all looked familiar, did the install while with Quality stainless Fabricators back in the 80's, originally was run with/ by a sanden SD508 comp anf if after removing the current one you should see SD 508 cast on the SD7 body, brilliant rugged compressors however the "7" came out with PAG (poly alkyene glycol) lubricant which is both hygroscopic as well as not really suited to low temp work and as a rule we'd dump it on install and revert to mineral oil 5GS always remembering to add on top of the 175ml oil charge another 100ml's for a single cabinet and 150 ml's for a separate fridge freezer. Isceon 49 was a short term interim R12 refrigerant dropin that was frankly a bit of a disaster in these systems and was pretty quickly dropped in favour of R406a which in itself is soon to disappear as well, R134a can be a bit problematic with these systems particularly in the -18>-22 degC range as the comp'll be running in a vacuum and likely draw air in via the shaftseal . The condenser, that's the bit with the brass nut in amongst all the verdigris will really need to be checked a soften at that time they were made from domestic 15mm copper tube on the inner, that brass nut by the way is an anode so if you remove it (use a ring spanner please) you should see that ends of the core tubes, if you can count 7 tubes then it'll be a domestic copper model and suggest replacing it, if on the other hand there are 4 tubes internal it'll be alloy bronze and be good to go again, the taller brass fitting next to it is a 350psi 1/4" npt henry relief valve and it , like the anode (3/8'BSP) would be due for replacement, looking at the other pic I see a liquid refrigerant receiver which allows the system to hold a larger refrigerant charge and for tropical use yes it does need to be there, also note that the receiver as well has a pressure relief valve and as you only need one in the system I'd suggest capping/ plugging the one on the condenser and replacing the one on the receiver. Yes you'll need to either remove the refrigerant charge or in the past I have pumped these systems down and removed the comp with the condenser and receiver and shutoff valve still connected however it looks like a little bit of a rats nest you'd be negotiating to do that here. Those low profile 90deg connectors to the comp as a rule present no removal problems and shouldn't require a flare washer to seal, where the flex hoses connect to the fittings does though, oh and one more thing............fit a thermostat to the freezer so it'll turn off when it has done its thing and not cook/ draw in moisture
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