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speedsport
11-01-2007, 08:35 PM
anybody know anything about recharging RV refrig that uses ammonia for refridgerant?, uses gas for energy source.

darryl
11-01-2007, 09:05 PM
I don't know about recharging them, but I find them interesting. One thing I discovered is that they don't begin to cool right away. They have to run awhile before the cooling cycle begins. Then they can continue to cool for some time after the heating part of the cycle stops.

Recharging- is it likely that if it needs a recharge that it has some 'issues' that need to be addressed- like pinholes maybe? I'm not sure, but I seem to recall that they work on a little higher pressure than a freon type would. You'd want to be sure of the structural integrity of the system before refilling it. I've seen a few of these type coolers in motorhomes and campers, and some of them look downright scary what with rust, etc.

J Tiers
11-01-2007, 09:15 PM
On the other hand, despite recalls and scare campaigns against them, they are the ONLY type that has the very REAL potential to work directly off solar energy. Heat is heat.

The same sun that heats up the house could cool it...... I understand that this is already done by the Club Med resorts on Martinique, but I have never seen details of the system.

platypus2020
11-01-2007, 09:25 PM
About 2 yrs ago had to throw a way a late 40's Kelvinator refrig, because the ammonia started to seep out of the coil, couldn't find anyone to fix it, as it was in a house, the tech said RV's (vented outside) and commerical refrigeration are the only ones currently using ammonia. There was a blurb on the news a while back, some Hyundias and Kias were shipped to the US with butane mix (used in Asia) in the AC units, instead of r134a.

oldtiffie
11-01-2007, 09:27 PM
Ammonia-based cooling was used in rural cooling sheds (some very large) in Australia for storing fruit for use and better "prices" in the "off season". They were usually sited with Packing Sheds as well.

We had them everywhere there were orchards with perishable fruit. This was well before modern chillers/coolers. The big problem was the cloud of ammonia if it leaked. But they gave good service in their day.

There are few if any left at all let alone operational I would think.

I don't know if the process would be viable - or perhaps allowed - today.

One of the several Refrig/Heating/Cooling professionals on this forum will be much better able to advise on this than I can.

speedsport
11-01-2007, 09:38 PM
A buddy of mine had this fridge in his motorhome, it started to leak ( I could smell the ammonia), the local RV place told him it was againist state law (Oklahoma) to repair these units, he bought a new one ($1010.00), he gave me the old one, I am gonna attempt to locate the leak and repair it. I have charged many air conditioners but have never worked on one of these, I want to do this for educational purposes.

wierdscience
11-01-2007, 10:00 PM
Ammonia units in RV's can kill you.A friend had one in his camper,they were off on a trip,the first night they ran the unit they smelled something funny,but paid no attention to it.Later he was outside the RV at the camp ground when he heard jis wife scream and come busting out the door onto the ground.The smell turns out had been ammonia leaking and once the unit had run awhile it built up enough pressure where the leak(in a soldered coil bend)let loose and emptied the contents into the living space.

She survived but barely.She had chemical burns on her arms and face from the ammonia and the ammonia she inhaled before escaping scared her lungs.If she had been asleep it could have been much worse.

If it were me I would run a pressure test on the system before I attempted any fix.Just a thought.

mechanicalmagic
11-01-2007, 10:13 PM
anybody know anything about recharging RV refrig that uses ammonia

I know little about recharging, except that it's an extreme hazard. Ammonia gas is highly toxic (lethal @ 0.5% ). It is also a problem on skin, and eyes.

Before you start cutting without breathing, find a place to buy Ammonia Gas. Airgas has 4# lecture bottles, and you will need a CGA 180 regulator, and probably a way to pinch off the fill line.

There WAS a company that provided rebuilt assemblies, saw it a few years ago. Send them your old frig plumbing, and get a fixed one back. Google may find it.

But, the real problem, (I've been told), is that these frig's don't usually fail from leaks. They fail because of crap that builds up in the orifices. If you can't get the crap out, it doesn't work, no matter if there is proper Ammonia.

Have you taken it out and left it upside down for a day? Supposedly this works (sometimes).

deltap
11-01-2007, 11:28 PM
Ammonia is still widely used in large cold storage and food processing facilities. It is not compatible with copper pipe so steel pipe and valves are used. In this application ammonia is the refrigerant and the vapor compression cycle is much the same as freon refrigerants. RV refrigerators work on a different cycle, the absorbtion refrigeration cycle. In this cycle a mixture of ammonia and water are charged into the refrigerator. Ammonia is the absorbent and water is the refrigerant. Pressures can be very high. When a unit leaks it is best not to repair it. A gas company (ARKLA?)built natural gas fired absorbtion residential chillers years ago. As in the refrigerators no compressor is used just a heat source. Many industries that have a waste heat source utilize lithium bromide/water absorbtion chillers. Sizes begin about 500 tons cooling. They can be gas fired or more commonly steam is the heat source.

Rich Carlstedt
11-02-2007, 12:21 AM
What deltap said is right on.
We had a major Ammonia leak at a Plant I worked at.
The fire department put on the Fog-Spray and went in.
Ammonia has a temendous affinity to water, and the vapors IMMEDIATELY
get absorbed, and run down the drain. When a leak occurs, the water in your eyes absorb this and that is why they burn, in fact, the
water in your skin is also exposed the same way, and the injuries are really burns . Smelling salts are not even comparable to a Liquid Ammonia leak..very dangerous..
Rich

gearedloco
11-02-2007, 12:23 AM
Ammonia is still widely used in large cold storage and food processing facilities. It is not compatible with copper pipe so steel pipe and valves are used. In this application ammonia is the refrigerant and the vapor compression cycle is much the same as freon refrigerants. RV refrigerators work on a different cycle, the absorbtion refrigeration cycle. In this cycle a mixture of ammonia and water are charged into the refrigerator. Ammonia is the absorbent and water is the refrigerant. Pressures can be very high. When a unit leaks it is best not to repair it. A gas company (ARKLA?)built natural gas fired absorbtion residential chillers years ago. As in the refrigerators no compressor is used just a heat source. Many industries that have a waste heat source utilize lithium bromide/water absorbtion chillers. Sizes begin about 500 tons cooling. They can be gas fired or more commonly steam is the heat source.


I've read numerous explanations, in various degrees of detail, of how the adsorption refrigeration cycle works. All of them seem to involve a fair degree of hand-waving, but that's probably due to my limited background in chemistry and physics. In any case, the process certainly appears to work.

BUT, any gizmo that gets cold when you build a fire under it seems to be dangerously close to witchcraft!

dp
11-02-2007, 12:47 AM
About 25 years ago I was working on a ship in Portland, OR installing a new radio direction finder. My helper and I stayed overnight on the ship as we had worked late into the night. It was an ammonia tanker.

That night after we'd turned in they had a burst tank or pipe - don't recall which, but the crew and entire city sector were evacuated. The crew forgot we were in guest quarters and when they abandoned ship we were left behind and slept through it all. The next morning we walked around the now ghost ship looking for people, then went out on the starboard bridge wing and saw the moonsuits working. They like to crapped their pants when they saw us walk out and wave. They had only just capped the leak and the ammonia had barely dispersed. Nobody knows why we weren't dead. Favorable wind off the Williamette River, I suppose, and that the port to the quarters was closed.

That's some bad stuff. I used to do refrigeration (air conditioning on yachts) work and I wouldn't touch it. Is that a Servel refrigeration process? I used to rent a house that had a Servel refrigerator and it worked great right up to the day it quit and then it went to the dump

Jim Hubbell
11-02-2007, 04:06 AM
I was chief engineer in a dairy. Ice cream production at about 25,000 gal. per day. Ammonia was the refrigerant used. 300 ton compression system. As was mentioned, the little RV units are absorbtion systems. I would definately NOT try a repair. The exact ammount of ammonia, water and possibly inert gas must be measured into the system. If it rusted thru in a pin hole there are many more just waiting to blossom.
I don't believe ammonia is toxic. It is highly irritating and will " burn " the mucus membrains along with the skin if the consentration is high. It must be handled with great respect. KNOW what you are about before you start.

Boucher
11-02-2007, 08:45 AM
RV's use the old Servel system. For basic explanation get out your old Thermodynamics text. This system is an adsorption system not a compressor system. Normally trouble free but heavy weight. Our Fridg went out recently. A rebuilt unit with labor was within $200 of the cost of a new unit. The new unit has several new features like a door lock that the old one did not. Better shelf arrangement and in door space. Ours would not come through the entry door. They had to remove the drivers seat and come in that way. New is the way to go.

Weston Bye
11-02-2007, 09:49 AM
If anyone is interested, I have a RV refrigerator free (if you pick it up) to good home. The ammmonia absorbtion type, runs on propane or electric - but the propane thermostat is broken. The unit is small - stands about 3.5 to 4' tall. Came out of an Airstream trailer.

Swarf&Sparks
11-02-2007, 12:08 PM
"I don't believe ammonia is toxic."

Tell that to the family of the young frigi who died servicing the freezer gear in a trawler here. And that was only a coupla years ago, not an ancient boat.

speedsport
11-02-2007, 12:17 PM
After reading some info I found on GOOGLE I have decided that fixing this thing ain't gonna be worth the effort for "educational purposes", seems that rust is probably the culprit and just finding one leak and fixing that is only a temp. repair because another small hole will likely appear soon, so you really need to replace the entire piece of pipe, plus the ammonia also has to contain a certain amount of hydrogen, I have way too many other irons in the fire to get distracted by this thing. I want to thank everyone who responded to my post, as always, a great forum.

Swarf&Sparks
11-02-2007, 12:19 PM
Sorry to rain on your parade, but ammonia is NH3, the H is hydrogen!

Forrest Addy
11-02-2007, 01:10 PM
Just or clarity's sake, there's two kinds of ammonia refrigeration. One uses a mechanical compressor like any other mechanical refrigeration often in very large scale operations.

The other is absorbtion where the ammonia refrigerent is absorbed in water, driven off with heat as from a kerosene heater, condensed in the usual fashon, then evaporated in the refrigerated compartment and back to the water flask for another cycle.

http://www.nh3tech.org/abs.html

The RV industry used absorbtion refrigerators for many years. So long as they are sealed tight and never tipped over they last for generations.

For the record ammonia is very detectable and leaks usually drives people out before toxic levels are reached. Ammonia in concentrations is very toxic and can cause excrutiating death. On lower exposure expect lesser injuries to eye and lungs. Ammonia and water combine to form a caustic (a chemical base) NH2OH. As was said water and ammonia have high affinity for each other.

joeby
11-02-2007, 06:46 PM
If you want to read up in the absorption type refrigeration units (RV), check out this website.

http://www.rvcool.com/

The steel tubing in these units is susceptible to rusting. Mine had a tube buried in the insulation rust through. I gave rvcool a call and had a rebuilt cooling unit in a couple days.

It wasn't difficult to change out, been working fine for the last two years. Much better price than a new refrigerator too!

Kevin

mvdavid
11-02-2007, 09:43 PM
When I was much younger I did a little with Servel units, propane and kerosene household type units. they were fairly maintenance free. Sometimes the chimneys would get restricted, or they would require " burping" which was accomplished in 2 ways that I know of... first shut the unit down for a day or more, then rock gently forwards and backwards a few times until a gurgling sound is heard. Then relight and adjust the flame, and hope for the best. If that didn't work stand the unit on its head for a day, turn it back to rightside up and try to operate it again.I was told by an old timer to never allow the unit to lay on its side. As I recall the pressures were in the 600 to 800 psi. range but am not at all sure about that. I recall that some had a mirror in the base to either help in adjusting the flame or something. Hope this helps.