The Only Real Cure for an Norcold RV Refrigerator "Problem"

[davecampbell]

Originally Posted by TXiceman

Ammonia will burn, in a very narrow combustion range, but only in the presence of a flame. No flame, no fire.

Let's not give ammonia a bad reputation based on hear-say and speculation.

Ken

KNow what Freon decomposes to?

Makes ammonia look pretty friendly....

[TXiceman]

Ammonia is a natural occurring chemical in nature. When it is released into the air, it disassociates into nitrogen (good for filling tires) and water (H20). Water will readily absorb ammonia (NH3). This why an RV frig will work.

The levels at which you can smell ammonia is very low and you have to get a really major concentration to be harmful to the lungs. Your eyes and nose will be burning a long time before it will cause permanent damage.

You can find more info on ammonia at http://www.iiar.org

Ken

[Ray,IN]

I can't say about today, but before I retired from the Army, Ammonia absorption refrigeration was mostly what the Army used.

[Sammie]

Originally Posted by TXiceman

Gary, a compressor driven unit is not any safer or more functional than an ammonia absorption unit.

Ammonia has been used as an industrial refrigerant since before 1900. In addition to ammonia, there was Sulfur dioxide (SO2) and methylchloride. When duPont came on the scene with the "Freon" (Chlorine based) refrigerants, ammonia was pushed to the rear and a lot of the ammonia technology was lost.

Ammonia is still the most widely used refrigerant in large cold storage and food preparation installations. Ammonia is the most efficient refrigerant in use today and it is even used in the cooling system on the International Space Station. I doubt if it would have been used there if it was so unsafe.

Ammonia will burn, in a very narrow combustion range, but only in the presence of a flame. No flame, no fire.

I have been in the industrial cooling field since 1970 and worked with numerous ammonia systems, both mechanical and absorption and have not had one blow up or catch fire due to the refrigerant being ammonia.

The newer ammonia absorption units are not being built to last as long as the older units. Our 1979 Silver Streak had the unit finally stop cooling when it was 29 years old. No leaks, no fires, etc. The systems have an anti corrosive agent in the mix to stop the corrosion.

Mechanical units are actually more prone to failure, due to the moving parts and they are also subject to electrical fires.

Let's not give ammonia a bad reputation based on hear-say and speculation.

Ken

Ken, I'm confused! Is leaking ammonia combustable, or is there another gas in these leaking cooling units that is causing these fires to start?

Sammie

[Ray,IN]

Actually when you read the http://www.sciencelab.com/xMSDS-Ammo...roxide-9922918
Ammonium Hydroxide has a flammability rating of "0". Pay attention to section 5, which states it is non-flammable. It does have serious health hazards.

[Sammie]

Originally Posted by Ray,IN

Actually when you read the http://www.sciencelab.com/xMSDS-Ammo...roxide-9922918
Ammonium Hydroxide has a flammability rating of "0". Pay attention to section 5, which states it is non-flammable. It does have serious health hazards.

OK Ray, So what is causing the refridgerator fires, just the heat that is caused when the cooling coils go bad?

Sammie

[Ray,IN]

Originally Posted by Sammie

OK Ray, So what is causing the refridgerator fires, just the heat that is caused when the cooling coils go bad?

Sammie

I don't know. I assume it is another chemical in the solution, Hydrogen perhaps? I just pointed out what the MSDS states.

[FreeByrd]

Take a look here and it will go through a simple version of the cycle of How the ammonia works in our refrigerators.

HowStuffWorks "Gas and Propane Refrigerators"

I was told it was actually Hydrogen Sulfide (the "yellow" stuff that stains the tubing when there's a leak in a cooling unit) It helps prevent the ammonia from corroding the steel tubing during the process but also makes the mixture volatile.
If TXiceman shows up he can probably tell us exactly what it is. But sure it DOES contain Hydrogen. . . . the same stuff that they put in the German Zeppelin HINDENBURG Airship that blew up in the 1937.

[bachler]

What an Interesting Post;;However In my many years. an apprinticship, in 1959 in R/Vs; In reallaty I like to refer to the time frame of 10 years; for things to last. Hot Water tank . Refrig. the list goes on and on; Tires Used to be 7 years ; Then after a few accidents. It was lowered to 3 years; We must remember in a unit like an R/V there may be as many as 5000 employees that worked on that unit and it's componants; The engineer that designed the board had a bad day Maybe?? Norcold has been trying to Rectafy the problem;; We all know we have bad days; I'm 72 And I know I had one. Then again Maybe I am wrong. Life is good; I have had to replace 2 refrig. Units . Between Our 7 coaches; Braking that down to the cost per hours of use thats. Pennys per hour;

[Gary RVRoamer]

I wasn't trying to give ammonia a bad name - its a very useful chemical. But the reports say that coolant mixture in an absorption fridge will burn under high heat conditions and I accept that at face value. Whether it is the ammonia component or the hydrogen sulfide or the sodium chromate makes little difference - it is in there. If the tank corrodes and the stuff escapes onto a superhot surface, a fire can result.

Compressor driven fridges can leak too, and freon compounds are nothing to mess with, but fires from compressor fridges are rarely reported. Possible, I'm sure, but not often heard of. And the refrigerant in a residential fridge is not inherently corrosive like an absorption fridge.

Let me say that my absorption fridges have all worked well, even my current Norcold 1200 LRIM. I'm not knocking all RV absorption fridges.

[Sammie]

Originally Posted by Gary RVRoamer

I wasn't trying to give ammonia a bad name - its a very useful chemical. But the reports say that coolant mixture in an absorption fridge will burn under high heat conditions and I accept that at face value. Whether it is the ammonia component or the hydrogen sulfide or the sodium chromate makes little difference - it is in there. If the tank corrodes and the stuff escapes onto a superhot surface, a fire can result.

Compressor driven fridges can leak too, and freon compounds are nothing to mess with, but fires from compressor fridges are rarely reported. Possible, I'm sure, but not often heard of. And the refrigerant in a residential fridge is not inherently corrosive like an absorption fridge.

Let me say that my absorption fridges have all worked well, even my current Norcold 1200 LRIM. I'm not knocking all RV absorption fridges.

Thanks Gary, That clears it up fr me.

Sammie

[RVhauler]

Propane was years ago used as a refrigerant. In Europe they were using propane in house window units. Imagine the excitment that a leak from that could cause if the compressor sparks/etc

[TXiceman]

The amount of propane used in a home type frig is measured in ounces. To leak it all in to a normal sized kitchen...you would hardly notice it as refrigerant grade propane has no odor. The odorant is added to fuel source propane for safety.

Propane and other hydrocarbon gases are widely used in many petrochemical plants and refineries. The systems are placed in to a Class 1, Division 2 electrical area classification. This is not explosion proof, but it could be an explosion or fire hazard in the event of a leak. Hundreds and hundreds and possibly thousands of units operate 24/7 without mishap.

The ammonia absorption units have a very small amount of hydrogen in them and some anti-corrosive agents. They had used chromates in the past and I do not know what is used now.

We also cool hydrogen in some processes, but the electrical classification and piping are designed to very rigid national standards regulated by NEMA, NEC, API and TEMA.

I do not know what is thwe cause of the fire other than they were adding a baffle around the burner are, so I suspect the fire was caused more by the heat source. There was also some problems from the electric heater and some cracking in the boiler. This was more of an electrical issue from what I have read.

I work on the larger industrial units and try to avoid the small units. If anyone has any other information on the sources of the "fires" due to the RV refrigerators, I would appreciate a response.

Ken

["007"]

Ken,The Doc has been tracking fires this post is in the Newmar Norcold & Dometic fire thread.