Heating Rapid-Tap (or: What Makes Phosgene?)

[bajajoaquin]

I was cutting off an axle shaft to make a hot cut hardy today, and I squirted a bit of RapidTap on the bandsaw blade. Popped the part into the induction forge, and it started smoking. Doh!

The doors were open with a cross breeze, and I didn't get much in my face before moving out of the way and letting it cool off. I don't feel any negative effects, but I'd rather not do that again. Anyone know if RapidTap is (relatively) safe to burn off? And more specifically, what is it in brake cleaner that makes phosgene gas? I wasn't using brake cleaner, but I know that's gnarly stuff and you don't want to weld it. I want to know what to look for as an ingredient in the future.

[Glenn]

According to the National Institute for Occupations Safety and Health (NIOSH), a phosgene toxic level that can place a person’s life and well-being in jeopardy can be as low as 2 parts per million (ppm).

Phosgene - Wikipedia,  Phosgene is the chemical compound with the formula COCl2. A colorless gas, in low concentrations its odor resembles freshly cut hay or grass. Phosgene  gained infamy as a chemical weapon during World War I where it was responsible for about 85% of the 100,000 deaths caused by chemical weapons.

You read this article about a welder and break fluid.  http://www.brewracingframes.com/safety-alert-brake-cleaner--phosgene-gas.html

Phosgene, things you NEED to know.

Phosgene Toxicity

 

IForgeIron is all about safety. If in doubt do not do it. If you get in a dangerous situation, leave immediately. A cross breeze is NOT sufficient to protect you. 

 

[Irondragon Forge ClayWorks]

Here is the SDS for Rapid-Tap, nothing mentioned about Phosgene gas when burning. I still wouldn't make a habit out of burning it though.

https://relton.com/wp-content/uploads/2018/06/SDS-NRT-V7.pdf

[Marc1]

I didn't know what Rapid Tap is so had to look it up.

It seems that it is just a lubricant and has no relation to brake cleaner. See below the link to the safety data sheet. Having said that the safety data has a few holes so, clearly not recommended to inhale fumes from combustion. 

As for Cobalt Chloride aka Phosgene, it can form by burning Tetrachloroethylene, an industrial degreaser also used for dry cleaning. (I think it is banned now but depends from the country you live in)

A comprehensive study by Akio Yasuhara in the thermal decomposition of Tetrachlroethylene is available with a Google search. Hydrogene Chloride and Phosgene is formed between 300C and 900C. There is no antidote to Phosgene poisoning.

Phosgene can also form in the combustion of refrigerant gases in fires that involve air conditioners or fridges. 

https://relton.com/wp-content/uploads/2015/03/SDS-NRT-2015.pdf

[SLAG]

Marc1,

There is no cobalt in phosgene.  The molecule is better known as  carbonyl dichloride.

Carbonyl is the chemical radical C=O. 

The molecule Cl-C=O-Cl. The C=O is central to the 2 chlorines and the =O is disposed at right angles to the two flanking chlorine molecules.

Tetrachloroethylene is more commonly known in North America as perchloroethylene. It was very commonly known, in the dry cleaning business, as "perc".

Regards,

SLAG.

 

 

[Frosty]

Old type carb and brake cleaners used to contain a chlorine component making them a phosgene formation hazard. Chlorine in the presence of carbon that is exposed to high enough energy can form phosgene. Phosgene poisoning may not express symptoms for a significant time after low exposures. Chlorine was taken out of carb, brake, degreasers, etc cleaners when it was discovered that just degreasing a work bench, the UV from an arc struck across the room caused phosgene exposures severe enough to need hospitalization. I don't seem to recall fatalities from those exposures.

One of the reasons phosgene was used so extensively as a poison gas during WWI was how easy it is to make. And NO I'm not going to mention any ways, the welding arc and chlorinated carb cleaner was bad enough. It's beyond nasty stuff, it's deadly, crippling, badness on steroids. if something catches fire in your shop and you smell fresh mown grass. GET OUT FAST!! Unless someone is mowing the grass outside. Burning PVC and many other plastics can generate phsgene. 

Is that close Slag? Its been probably 17 years since the llast emergency responder fire and toxic stuff course. Being an operator for DOT Highways meant we were on the front line in a disaster if we qualified. Some of the guys couldn't chew gum and sit still.

Frosty The Lucky.

[bajajoaquin]

Yes, there were separate questions in there: 2. what is the component that makes phosgene? Seems to be chlorine, right?

1. Anyone have an opinion on what's in RapidTap?

And yes, I stopped what I was doing as soon as I realized I was smoking the RapidTap. I just decided to ask the follow up question about a known killer while fumes were on my mind.

Thanks!

[Frosty]

Chlorine is the key but the stuff is made of: chlorine, carbon and oxygen plus energy to bind them all: heat, electric spark, strong UV. It may take fire temp heat but maybe not. Maybe Xray or microwave radiation would do it, the class didn't go into the details, they just wanted us to recognize dangerous situations, what we might expect and how to deal. 

Frosty The Lucky.

[SLAG]

 Herr Frosty,

You are correct.

Also, I should like to point out,  that the fresh mown grass smell does NOT always accompany the out-gassing of phosgene.

The symptoms often do not become apparent until some days after exposure.(especially so,  for lower amounts/doses of that gas).

The reaction that synthesizes phosgene, is to pass chlorine into carbon monoxide, over a bed of activated carbon.

But the carbon is not necessary. Ultraviolet light will do the same thing. (arc welding produces enough u. v.) 

But not gamma radiation nor microwave radiation.

Chlorinated organic solvents (like degreasing solvents),  slowly decompose to give forth chlorine gas.

The reaction is much faster when organo-chlorides burn.

SO store all such solvents far away from any arc welding station,  Preferably in another room or building.

Also,  stay away from fires burning near air conditioning units, or halon gas storage sites.

SLAG.

 

[Frosty]

Thanks Slag, good to know my memory is still good enough to maybe keep folks out of trouble. 

Delayed reaction is due to how slowly it can cause renal failure? Once in you it doesn't metabolize so it keeps doing damage. Close? 

Freon, halon, etc. Chloro floro carbons are badness all by themselves. At least getting exposed in a refrigerant leak say at a skating rink or being in the same room if a halon fire extinguisher goes off will get you immediately and if they treat you soon enough it's treatable. 

The Xray, microwave thing was just speculation. WHEW! I can go back to cleaning glassware with trichlorethylene in the microwave.  I got pretty familiar with Tric in the materials lab. Heck, I got that job when the asphalt lab tech turned the condenser water off but left the heat element on in tric still over Memorial Day weekend. They don't know how long it boiled tric till the asphalt caught fire but everything and I mean EVERYTHING was covered is tarry sooty stuff. The union called me out to help clean up the mess. Later I found out the whole building had been closed and decontaminated for something like a week. 

Nobody said a thing about possible phosgene contamination but one of my jobs after the clean up was to hang hazardous material signs all over the place. first time I saw the word phosgene but didn't learn anything about it for years.

Things have changed since the mid '70s eh?

Frosty The Lucky.

[Marc1]

6 hours ago, SLAG said:

Marc1,

There is no cobalt in phosgene.  The molecule is better known as  carbonyl dichloride.

You are correct, Carbonyl Chloride not Cobalt Chloride. My bad.  (Co ff Co ff  )

5 hours ago, bajajoaquin said:

2. what is the component that makes phosgene? Seems to be chlorine, right?

1. Anyone have an opinion on what's in RapidTap?

1) Lubricant. Not safe to breath fumes.

2) Tetrachloroethylene (industrial degreaser) not chlorine 

[John McPherson]

What if boils** down to is: don't heat anything with chlorine or fluorine compounds listed on the label. ALWAYS READ THE LABEL. What you don't know can kill you.

**Or is that Boyles' Law in this case?

[ThomasPowers]

IN RUST WE TRUST   (Glenn sells the shirt!)   putting stuff in the forge that is not iron/steel/rust is generally not a good idea. (Now I have hot forged bronze, copper and silver; but not anything like that plated or painted.)

[Frosty]

17 hours ago, Marc1 said:

Tetrachloroethylene (industrial degreaser) not chlorine 

Chlorine is a main ingredient in TetraCHLOROethylene.  Tetra meaning 4 in chemistry.

Frosty The Lucky.

 

[Marc1]

Very funny. 

Carbon is the main "ingredient'" in petrol. Somehow the servo will not fill the tank with carbon if I ask ...

But if you think that cleaning with Tetrachlor or bleach is the same ... you have something else coming. 

Then again ... there are scores of people who think that "carbon" is real bad and we must de-carbonise to reduce our "carbon" foot print.

Go figure ... yes chemistry is interesting, sarcasm is not.