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Port-Holio
07-29-2009, 11:03 PM
Yes, welding parts cleaned by Brake Cleaner CAN kill you!!!!!! :ack:

This article has been getting passed around on the internet lately:

http://www.brewracingframes.com/id75.htm

Here's my $0.02 as a chemical engineer (sorry for the doctoral thesis, if I had more time, I'd write a shorter article)

This is absolutely true, in no way exaggerated or urban myth.

NEVER expose Freon, Electrical Contact Cleaner, or non-flammable Brake Parts Cleaner to fire, sparks, or high heat.

When exposed to fire in open air, they will release vapors which become strong corrosive acids upon contacting water (ie skin, eyes, lungs).

But even worse, when exposed to fire in an inert atmosphere, especially Argon TIG/MIG welding, they produce a deadly poison called Phosgene.

Now when I say “Non-flammable” I’m not talking about Simple Green, Windex, etc. I mean only solvents, which are usually in spray cans. The most common are labeled “Electric Contact Cleaner” or “Non-flammable Brake Parts Cleaner”. Among the contents, Trichloroethylene, Carbon Tetrachloride, Chloroform will be listed, and are the ones to avoid.

Any cleaner with “CAUTION - FLAMMABLE” on the label is perfectly safe to use for metal prep prior to welding (just don’t set the shop on fire). In fact, “CAUTION - EXTREMELY FLAMMABLE” is even better!

Phosgene killed it’s first few discoverers because the German chemists always had a fetish for including "taste" in the properties of newly discovered chemicals. Later it’s properties and the desperation of the German Army led them to introduce it as a chemical weapon against the Allies in World War I. It was banned by the Hague Convention for Land Warfare, which was signed by all civilized nations immediately after The Great War.

Phosgene is colorless, tasteless, and nearly odorless, although when formed it is often accompanied by the familiar swimming pool smell of chlorine. It doesn't trigger body responses like coughing, or irritation that might prevent you from taking full breaths of it. It vaporizes easily, and likes to linger around in basements and shell craters because it's heavier than air. It can be fatal in concentrations as low as 4 parts per million (10,000 times more dilute than when your friend farting in your garage).

The Germans who handled it smoked cigarettes constantly because the cherry's heat partially breaks it down and makes the smoke taste weird. Otherwise there was no immediate way to notice being exposed to it. High concentrations are immediately fatal. Allied soldiers occasionally reported a faint smell of freshly mown hay right before everyone started falling down dead. A couple breaths at lower doses can still be fatal, although you might not notice anything for 6-72 hours. Non fatal doses can have painful complications for months afterwards. The guy who wrote this article seriously had 1.75 feet in his grave.

Argon is key to it's formation during welding, but the hazard is not specific to Argon. What's going on is that phosgene is formed by decomposition of chlorinated hydrocarbons in high heat in an inert atmosphere. MIG/TIG arcs make an ideal reactor. The inert atmosphere prevents it from combining with nitrogen or oxygen instead to make other less harmful by products. Any inert noble gas (Argon, Neon, Krypton, Xenon) will do the same thing, as might CO2. Free Chlorine is also released - it too was used as a chemical warfare agent.

The three essential ingredients for disaster here are:

1. Halogenated Solvents (contain Chlorine, Fluorine, Iodine or Bromine)
2. Electric Arc/Ultraviolet Light/Combustion Temperatures
3. Inert Atmosphere

Skip any of them, and you stop the threat. This is why electricians aren't dying when they plug in electric motors they just sprayed with contact cleaner - the O2 and N2 in free air prevent formation of phosgene - instead it makes acids that aren't good for you, but not nearly as bad.

Chlorinated solvents are not "flammable" in the everyday sense, so there is NO threat from the spray cleaners with a "Warning - Flammable" label. In fact, the more flammable it is, the least risk of toxic gases.

Mostly, the only cleaners still allowed to contain lots of Carbon Tetrachloride are labeled "Electrical Contact Cleaners". Staying away from anything "Non-Flammable" for welding jobs is a rule that won't ever steer you wrong.

The phosgene risk of chlorinated solvents has largely been taken care of by the EPA. Carbon Tet and almost all halogenated (halogen = fluorine, chlorine, iodine, bromine) solvents have been taken out of general public use by the ban on CFC's to protect the ozone layer. CFC = Chloro Fluoro Carbon = petroleum where some of the hydrogens have been replaced by chlorine, or fluorine or mix of both.

CFC's still exist in electric parts cleaners and some brake cleaners, because they have to leave no residue, and in some cases nothing else does the job.

greasy rotor = car crash………dirty circuit board = plane crash.

Trouble started when TIG/MIG started really catching on before CFC's were on the way out. Was also before we started putting safety warnings on everything, back when people knew that "DANGER" always meant real danger, so they would actually read the label.

If it sounds WAY TOO EASY to make chemical warfare agents in one's garage, sleep easy. Anyone trying this for evil purposes will kill themselves even attempting to create/harness the byproducts, let alone distribute them.

Ironically for us car guys, phosgenes are used most often to make intermediate chemicals for making iso-cyanates, i.e. Loc-tite, Super Glue, and epoxy primer paint. Don’t worry, they are reactants, and are used up long before the final products ever get to the store shelf

Swords into plowshares huh?.......

Port-Holio


Ps - here’s some of the gory chemistry involved for you masochists out there.

The mechanism where UV splits the CFCs, to recombine into phosgene, is the same reaction with UV light that breaks down the CFCs right above the ozone layer in the upper atmosphere. It splits off the chlorine, which is a then catalyst for turning ozone into regular oxygen.

Tri-chlor is Trichloroethylene C 2 HCl 3 , used to be a pretty common degreaser

Cl Cl
\ /
C = C
/ \
Cl H

Carbon Tetrachloride is CCl 4 it evaporates like crazy, hence it's overwhelming popularity in the past as a dry cleaning solvent.

Cl Cl
\ /
C
/ \
Cl Cl

Freon, just for giggles is Dichlorodifluoromethane - the CFC poster child. Welding full A/C lines probably is a good invitation for making Phosgene too.

Cl F
\ /
C
/ \
Cl F

adding UV light to any of these breaks chemical bonds, which makes all kinds of unstable compounds called "free radicals". Free Radicals will react with almost anything to become more chemically stable. Free Radicals are what make you get old and get cancer from tanning too much. They drive most chemical reactions here on Earth, and possibly life itself.

With UV/high heat and inert atmosphere, all CFC’s will produce varying amount of Phosgene from trace amounts of oxygen. The arc welding process is particularly efficient.

Cl
\
C = O
/
Cl

ryans88gt
07-29-2009, 11:32 PM
6 bonds to carbon in the first structure... tisk tisk.

Interesting though, I wouldn't really think about something like this.

RLS!
07-29-2009, 11:38 PM
I should be dead, apparently. :thud:

ryans88gt
07-30-2009, 12:11 AM
I should be dead, apparently. :thud:

Maybe you are dead and this is hell? :evilgrin: Just a thought. :whacko:

PBR
07-30-2009, 12:28 AM
Bla Bla shit i should have kicked the bucket also thats just a statistics thing man.

Sohcgt96
07-30-2009, 02:20 AM
Still, that is something we should all keep in mind!

Does Safety Kleen fall into that category I wonder? Actually, come to think if it I'm going to guess no, its so widely used if it was a CFC the EPA would have fits.

plum360415
07-30-2009, 02:21 AM
you never can use too much brake clean......

mitsu90
07-30-2009, 03:39 AM
I should be dead, apparently. :thud:

No shit you should see some of the oily shit I have welded on...


But the worst by far had to be the night I welded over ranch dressing :ack:

Port-Holio
07-30-2009, 09:40 AM
Haha, nice to see SOMEONE is counting electron pairs....FWIW I HAD the correct structure in there, but I guess the posting software took out what it thought were all the "unneccesary" spaces.....

Yeah, I've prolly done what I say not to do about a billion times too, I'm still alive. Just letting stuff dry completely before welding, or blasting the pieces with some compressed air before you start.

.....but like the guy in the story all you need is a couple drops of the wrong stuff hanging out in a couple rust pits one day to ruin your life?

Samickguy15
07-30-2009, 09:44 AM
So is this an issue with residue or with the stuff in liquid form, because the majority of it all evaporates, and there is little to no residue left over...

Port-Holio
07-30-2009, 09:56 AM
It's just an issue of the raw chemical sticking around in enough quantity to react with the arc inside the gas blanket. BY LAW brake cleaners/contact cleaners can't leave any residue when dry - safety issue

that's basic difference between brake cleaners and other cleaners - carb cleaner & starting ether both leave oil behind to prevent corrosion.

The EXTREMELY FLAMMABLE stuff in the orange can at AutoZone is my fav ESP for paint prep! I must use a case of that a month. It also makes the BEST flamethrowers with a lighter.

-ps I'm still LOL about how we might all be dead from this and already in hell. That sure explains the way my distributor rebuild is going.....

shelby5k
07-30-2009, 05:00 PM
i read about this on another forum. its some good info.

RLS!
07-30-2009, 06:16 PM
Maybe you are dead and this is hell? :evilgrin: Just a thought. :whacko:

That's deep. :)

standard235
07-30-2009, 06:34 PM
Whoa... I've had this exact discussion with my chem teacher because I mentioned something about welding and she knows I work on my car/friends' cars.

Made for a really cool lesson though, compared to teaching out of the book. Electron Pairs ftmfw!

Port-Holio
07-31-2009, 02:50 PM
I shouldn't have started out w/ the firehose version. Here's a good note to end on:

THE FACTS WORTH REMEMBERING IN THE WELD SHOP

If you use just any type of brake cleaner for MIG/TIG prep, making sure it has COMPLETELY evaporated will get rid of 99% of the risk of making a chemical warfare agent - but that 1% can kill you for real or mess you up for the rest of your life.

If you use ONLY flammable cleaners for welding prep there is NOTHING to worry about.

Putting Freons/CFCs/non-flammable solvents in a fire barrel will make an irritating gas like that brown shit in Top Fuel exhaust that burns your eyes. If a bunch gets directly on your skin, could get a rash like poison ivy.

For the same reason, wear gloves if you handle Viton® rubber or Teflon® plastic seals burned in an engine fire, be sure you wash your hands with water afterwards.

ryans88gt
07-31-2009, 03:25 PM
I shouldn't have started out w/ the firehose version. Here's a good note to end on:

THE FACTS WORTH REMEMBERING IN THE WELD SHOP

If you use just any type of brake cleaner for MIG/TIG prep, making sure it has COMPLETELY evaporated will get rid of 99% of the risk of making a chemical warfare agent - but that 1% can kill you for real or mess you up for the rest of your life.

If you use ONLY flammable cleaners for welding prep there is NOTHING to worry about.

Putting Freons/CFCs/non-flammable solvents in a fire barrel will make an irritating gas like that brown shit in Top Fuel exhaust that burns your eyes. If a bunch gets directly on your skin, could get a rash like poison ivy.

For the same reason, wear gloves if you handle Viton® rubber or Teflon® plastic seals burned in an engine fire, be sure you wash your hands with water afterwards.

Viton and teflon are perfluorinated and not nearly as toxic as their chlorinated anologs. Not likely to cause any problems unless you are directly inhaling the fumes while it burns.

Port-Holio
07-31-2009, 03:46 PM
:mad: HEY, there's only room in these parts for one chemist!! :mad:

J/K

That was our form letter warning we used to hand out everytime there was a panic about residual HF from Viton...Isn't HF>HCl in reactivity? (taxing my memory here). I know firsthand that conc HF on a fingernail makes a pretty painful blister underneath it.

I can't believe you didn't bust me on lumping nitric acid in with the protonated halogens.....:p

PaulFord8
08-01-2009, 08:37 PM
PB Blaster is flammable right? I will have to look... I am trying to free some bolts up and just sprayed the hell out of them. If that doesnt work plan B is to torch the hell out of them..

The welding thing is something to think about... Like many of us I have been in a hurry to tack something and just pulled the trigger without thinking about what vapors I maybe creating..

Sohcgt96
08-01-2009, 09:51 PM
PB Blaster is flammable right? I will have to look... I am trying to free some bolts up and just sprayed the hell out of them. If that doesnt work plan B is to torch the hell out of them..

The welding thing is something to think about... Like many of us I have been in a hurry to tack something and just pulled the trigger without thinking about what vapors I maybe creating..

i <3 PB blaster!

I've only ever found one thing better, and its hard to find, but its called Aero-Kroil and all the old-time Mechanics out at Altorfer who have been wrenching on big diesels for the last 30 years swear by it.