extremely unlikely to ignite

After reading DuPonts MSDS for 410 I'm not too worried about it igniting. It takes such a specific set of circumstances to ignite it's not very likely to happen by accident. You would almost have to try and ignite the stuff in order to get a flame.

Flammable Properties

Flash Point : No flash point

Flammable Limits in Air, % by Volume:
LEL : None per ASTM E681
UEL : None per ASTM E681
Autoignition: Not determined

Fire and Explosion Hazards:

Cylinders may rupture under fire conditions. Decomposition
may occur.

Contact of welding or soldering torch flame with high
concentrations of refrigerant can result in visible changes
in the size and color of torch flames. This flame effect
will only occur in concentrations of product well above the
recommended exposure limit, therefore stop all work and
ventilate to disperse refrigerant vapors from the work area
before using any open flames.

R-410A is not flammable in air at temperatures up to 100
deg C (212 deg F) at atmospheric pressure. However,
mixtures of R-410A with high concentrations of air at
elevated pressure and/or temperature can become combustible
in the presence of an ignition source. R-410A can also
become combustible in an oxygen enriched environment (oxygen
concentrations greater than that in air). Whether a mixture
containing R-410A and air, or R-410A in an oxygen enriched
atmosphere becomes combustible depends on the
inter-relationship of 1) the temperature 2) the pressure,
and 3) the proportion of oxygen in the mixture. In general,
R-410A should not be allowed to exist with air above
atmospheric pressure or at high temperatures; or in an
oxygen enriched environment. For example: R-410A should
NOT be mixed with air under pressure for leak testing or
other purposes.

 

How did the accident happen with your friend?

 

Pulling a large suction line off of a dx chiller barrel, pressure neutral after recovery, source of ignition was the torch being used on the brazed joint. I don't know all of the minute details. Could have been some oil lying in the entry section of the barrel that started degassing as the flame warmed the steel on the head, or something to that effect. Barrel had a leak and they couldn't get it down as far as they'd have liked during recovery, but even that wouldn't have helped in the scenario that I described unless it was left sitting under vacuum long enough to completely degas the oil. As mentioned, it has to be certain circumstances, and those circumstances have been proven to be attainable without trying too awfully hard. It's a misleading technicality in my opinion for the MSDS to say no flash point, and then on into the body of the document state that it's flammable under certain conditions. I'm sure this is not the only substance out there with this same kind of misleading wording in the MSDS, but it's one that I'm aware of now.

 

Not mixed with air under pressure for leak testing?

I only use dry nitro, but not mixed with air under pressure? Huh, I can see a problem there.

 

Looks like you're reading something into the post that isn't there. No one said a word about pressurizing anything.

 

Good info to know. I was always worried about getting laid out by mustard gas! Now I'm even more concerned, because a skin graft would suck!

 

I had a tech from another company tell me that he was changing the drier cores on a 410 chiller one time and the rags he used to wipe out the drier shell ignited. He wasn't using a torch or any other heat source. He simply wiped out the shell, laided the rags down and a short time latter they caught fire. I did some checking and found out about this happening a couple of other times in other areas. I haven't heard of any more cases, and that was about a year ago.

 

BS. Spontaneous combustion?? He put you together like a cheap suit.

 

he was changing the drier cores on a 410 chiller one time and the rags he used to wipe out the drier shell ignited. He wasn't using a torch or any other heat source. He simply wiped out the shell,

Gone are the days when a shot from the GREEN can put out any fire smoking in the compressor room. Now I have to buy a fire extinguisher or two.

 

Read the last 3 lines of the refrigerants spec sheet.

It says........

 

Just a reminder. On a system that has a leak, that prevents you from recovering to a vacuum.

If your going to use a torch to unbraze a joint. Flow nitrogen. It will help to keep the refrigerant to air mixture dilute enough that it will not take a flame.


Sorry to hear about your friends accident.

 

For the record Davy, if you read my post, I said (I did some checking). The checking I did was with a Carrier Support Engeneer, who stated he had heard of this problem happening a couple of times before, and he reported it to the engineering department at Carrier. As of this time he has not heard back from them. So for now, everyone be careful.

 

I feel the same way about R-152a. I was able to get R-152a duster to light up with a barbecue manual igniter, and it comes with a warning not to use it on a paper shredder (because sparks from motor may ignite the gas that may pool inside the shredder bin.

I don't know how they come up with a claim that this stuff is not flammable. This thing will burn on its own like fuel when ignited.

I don't know why don't just use unodorized propane/butane blend. They're flammable too, but they don't give off hydrogen fluoride gas when they burn like R-152a, or R-410A.

 

I don't know how they come up with a claim that this stuff is not flammable.

Because its not.

Non flammable doesn't mean it doesn't burn. It means it has to be heated to 100°F or more to burn.

 

Kerosene is not flammable by your definition. I think you're talking about flash point.

R-152a in air will ignite like gasoline when exposed to sparks.

 

I was taught early that almost all refrigerants are flamable. This is the main reason you NEVER pressure test with air with AIR!!! (not only because air has moisture in it)

I learned this in the USAF doing aircraft cooling.

Klove,
The reason I'm using the word pressurize here is to emphasize the fact that you can have an explosin here. If air is used in a closed system that has residule freon in it, you have a greater chance of getting that mixture that becomes flamable or combustable. It just makes the conditions more favorable for the two to react.

As I mention to people I work with, " Be carefull, this is a dangerous business."