Jor
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carbon tetrachloride fire extinguishers
We all know CCl4 is a very hard thing of us, although not for me, but it doesn't matter in this topic.
Now I always knew that this stuff was used a long time ago to extinguish fires, but I never knew that you can still buy these things! Although they
are not produced anymore, one can still buy them second-hand!
For example in the US, after 30 seconds of searching on eBay, I found this:
http://cgi.ebay.com/Vintage-Quick-Aid-Fire-Extinguisher-Secu...
This one contained CCl4, but it is empty. But there should be ones out there, still containing CCl4 I also found some one a dutch website, containing
CCl4.
Before you buy, ASK if it is still filled!
Look for the old copper/brass ones, some of them contain CCl4, others pyrene.
Who was aware of buying these things, and has actually taken the CCl4 from it?
The trick is getting it out. It is probably mixed with some kind of gas, wich will quickly disperse it as fine droplets when the valve is opened.
Maybe attach a large tubing to the opening, and slowly open the valve, and cool the CCl4 vapour in an effecient condenser?
So now CCl4 is suddenly in many people's reach? 
EDIT:
After a little googling, I think this one is full:
http://www.rubylane.com/shops/manylittle/item/con1286
Im not sure of contents, but he does not mention empty and tells how to use it.
This is expensive, but you empty it and sell it again.
[Edited on 29-3-2009 by Jor]
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JohnWW
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A CCl4 fire extinguisher would have to contain a non-flammable and non-oxidizing gaseous propellant, besides the CCl4 (boiling pt. 76.8ºC), under
high pressure. The most likely gaseous propellant would be N2, but a mixture with CO2 would be quite possible. However, because of its alleged liver
toxicity, CCl4 for fire extinguishers have been replaced by BCF ones, containing liquid pressurized bromochlorodifluoromethane (Halon 1211 or BCF),
CF2ClBr, which is substantially more expensive, and which vaporizes on release at atmospheric pressure (b.pt. -3.7ºC) unlike CCl4, without the need
for a propellant. But even this, being a volatile chlorobromocarbon, is now out of favor because of its ozone-layer damaging property. It is still
used on board ships and aircraft, being useful for extinguishing burning fuel.
See:
http://en.wikipedia.org/wiki/Bromochlorodifluoromethane
http://encyclopedia.airliquide.com/sds/en/008_AL_EN.pdf
http://en.wikipedia.org/wiki/Carbon_tetrachloride
http://www.britannica.com/EBchecked/topic/95076/carbon-tetra...
http://www.oehha.org/air/chronic_rels/pdf/56235.pdf
Otherwise, CO2 fire extinguishers are now usually used instead, although having a lower boiling or sublimation point (sublimes -78.5ºC at 1 atm.
pressure, but with a liquid range under pressure) it has to be kept in heavier vessels under greater pressure. Another good possible substitute would
be CF4 (b.pt. -128ºC).
[Edited on 29-3-09 by JohnWW]
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Jor
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Quote: Originally posted by JohnWW  | | A CCl4 fire extinguisher would have to contain a non-flammable and non-oxidizing gaseous propellant, besides the CCl4, under high pressure. The most
likely gaseous propellant would be N2, but a mixture with CO2 would be quite possible. However, becauise of its alleged liver toxicity, CCl4 for fire
extinguishers have been replaced by BCF ones, containing liquid pressurized bromochlorodifluoromethane (Halon 1211 or BCF), CF2ClBr, which is
substantially more expensive, and which vaporizes on release at atmospheric pressure unlike CCl4. But even this, being a volatile chlorobromocarbon,
is now out of favor because of its ozone-layer damaging property. CO2 fire extinguishers are usually used instead, although having a lower normal
boiling or sublimation point it has to be kept in heavier vessels under greater pressure. Another good possible substitute would be CF4.
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Just a guess, but can CO2 be used as propellant? Is it maybe possible CO2 and CCl4 react at high pressure in the cylinder to form some phosgene?
I think there are 3 reasons why CCl4 extinguishers are banned:
-CCl4 is a liver toxin, and a probable human carcinogen. But after reading many papers, i think CCl4 is not that toxic actually, it's become a hype.
TLV is 5ppm, so someone, who is exposed 8 hours a day, his entire life, at 5ppm is believed to suffer NO effects. 5ppm is pretty high for a chemical
wich is said to be so nasty, etc. It is also said that after high exposures, if exposure is not too high, the liver will heal itself again, by
repairing the cells.
It is a probably carcinogen, but a weak non-genotoxic one, requiring long-term, high exposures, to significantly increase chances of cancer.
-CCl4 is bad thing for ozone layer.
-The worst: in a fire, at very high temperatures, CCl4 will hydrolyse to form COCl2 and HCl.
Regarding the first point, I wonder why everyone takes CCl4 so seriously. I did first, because of stories, but after reading things, I doubt it is as
bad as people say. It seems like people like to greatly excaggerate over some carcinogens, like benzene and CCl4 (I may not even use this at
university in a fume hood for a synthesis), while other, more potent carcinogens like formaldehyde, are still used to clean garages of farmers...
No logic.
[Edited on 29-3-2009 by Jor]
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Sauron
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We are chemists not sirefighters. CCl4 is not that hard to make and as chemists, when we need something we can't buy, we make it.
You can make it from DCM or from CS2 according to your preferences. For that matter you can make it from ethanol via chloral and trichloroacetyl
chloride (which falls apart to CCl4) or similarly starting from acetic acid.
In every case plan on adding lots of Cl2, and often UV.
Sic gorgeamus a los subjectatus nunc.
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PHILOU Zrealone
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| Quote: Originally posted by Jor |
Regarding the first point, I wonder why everyone takes CCl4 so seriously. I did first, because of stories, but after reading things, I doubt it is as
bad as people say. It seems like people like to greatly excaggerate over some carcinogens, like benzene and CCl4 (I may not even use this at
university in a fume hood for a synthesis), while other, more potent carcinogens like formaldehyde, are still used to clean garages of farmers...
No logic.
[Edited on 29-3-2009 by Jor] |
It is not short term toxicity that matters here but long term exposure; also as chemist one would have to handle a lot of chems during his entire
life...thus a little of this, a little of that, plus a tea spoon of that also...then you get rivers out of tiny drops...careless use of chems can only
lead to premature death...
I once worked 3 monthes in a lab during summer...they used a lot of CH2Cl2 for large chromatographic trials, with the heat and despite fumehoods you
could nearly see the fumes of boiling CH2Cl2 coming out of the bottles and flow on the ground out of the fumehoods and then into the lab...I had a
bloodtest short after that and it was noticeable that I had a strong liver response (hepatoprotein) by comparison with a precedent blood analysis one
year earlier...
Prior to that work I had not to work with chems for a few years...
I can't imagine what will happen to the people who will work there for years...
So following the inverse rule, whit tiny protective cautions here and there, one can increase his health... drops --> rivers 
[Edited on 31-3-2009 by PHILOU Zrealone]
[Edited on 31-3-2009 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Contrabasso
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Several patterns of carbon tet extinguishers had a T handle -this was for a pump that simply manually pumped the liquid out - no propellant gas!
Carbon tet is out of favour for all the malaevolent gasses that exist after pyrolysis inc chlorine, chlorine oxides et al.
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