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While checking my engine oil the other day I noticed rust on the bottom of a part of my refrigeration system. It's a eutectic unit driven from the engine. The rusty part is the small tank with the glass window on top to check for bubbles (can't remember it's name !).

I need to dismantle the system to get some new hoses made up for the compressor and also check on this rust. I know there is all sorts of regulations that apply to working on this equipment and wondered if anyone could tell me A. Where one drains the system from and B. what is the best method to contain the drained fluid. The system is around 20 years old but I have no idea what refridgerent is in it, but would assume it's the old eco unfreindly variety.
 

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While checking my engine oil the other day I noticed rust on the bottom of a part of my refrigeration system. It's a eutectic unit driven from the engine. The rusty part is the small tank with the glass window on top to check for bubbles (can't remember it's name !).

I need to dismantle the system to get some new hoses made up for the compressor and also check on this rust. I know there is all sorts of regulations that apply to working on this equipment and wondered if anyone could tell me A. Where one drains the system from and B. what is the best method to contain the drained fluid. The system is around 20 years old but I have no idea what refridgerent is in it, but would assume it's the old eco unfreindly variety.
Being an older system, more than likely it's a R12 system (it IS illegal to release R12 into the atmosphere) and that requires a recovery system and a licensed tech to operated it. You can no longer buy R12 without that license. Can you say 'HEAVY FINES' if you get caught?:( Besides, releasing R12 can be hazzardous to your health. If the engine is running or there is an open flame source (as in making coffee on the stove or running a propane heater), phosgene gas is the result of burning R12 and it is a severe respiratory irritant. If liquid R12 comes in contact with skin or eyes, especially the eyes, it can burn. IMHO, it's just not worth the risks to save, well maybe more than a few, bucks.

Even if you can find someone to recover the R12, you still would have to round up all the parts, evacuate the system and then refill the system with 134a and the proper lubricant. That cylinder you mentioned is the drier and that will have to be replaced as well because of the moisture and the non-compatible oil the R12 system uses. Doing that will require specialized equipment, vacuum pump, gages and the expertise to know what to do with them. The average sailor is just not equiped with that kind of expensive epuipment.

You might want to look into the newer 134a systems, they have come down in price over the years and it may be cheaper and a more reliable option than rebuilding your old system.
 

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The small tank is called the drier. It holds excess gas from the system and I believe removes moisture. Unit driven by the engine is probably the compressor. If the system is 20 years old it probably has R12 in it. This is the stuff that depletes the ozone and is not used anymore. I believe that reclaimed R12 is still available to use in old existing systems that use R12 for refrigerant. I think that you are supposed to hire a licensed refrigeration technician to pump down the old refrigerant. You probably should change the drier as well and check the shaft seal in the compressor for leaks. You'll need a technician as well to recharge (after repairs) as you need to use a vacuum pump to evacuate the system and a set of gauges for recharging. You can't use new ozone friendly refrigerant with the old compressor because it will have mineral oil in it. New refrigerants require polyester oils. There is a blend on the market called RS24 that is a drop in replacement for R12 ,is ozone safe and can be used with the mineral oil. If the system is 20 years old it might be a good time to replace it. I used to have an older system with engine driven refrigeration and I was replacing or repairing the compressor about every three years. If the boat is stored during winter the shaft seal on the compressor often dries out causing gas in the system to leak out. I'm no expert. I've just watched the technician work on my systems over the years .There is a very good section on refrigeration in Don Casey's book "This Old Boat".
 

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The posts above are right on. You cannot "drain" the refrigerant even if you wanted to violate the law. R12 is under pressure in the system and will immediately boil (at -21F) if released to the atmosphere. Once you lose the charge, you will have no way to purchase new R12 to replace it without getting an EPA certified technician involved.
 
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