The Age of Carbontet

About Carbontet

Carbontetrachloride, also known as Carbontet, CT, CTC or VL (vaporizing liquid) and various brand names, is a halogenated chemical agent that first came to the US from Germany in the late 1890’s. It is a clear liquid with a distinctive pungent odor, is virtually illegal to ship by any normal means and is toxic to humans. When exposed to high temperatures it combines with moisture in the air to produce Phosgene gas, one of the chemical warfare agents used in WWI.

Common Uses

• Industrial solvent for cleaning and degreasing equipment or parts
• Replaced gasoline (yes, that’s right, gasoline) as a dry cleaning fluid for a time
• Household spot remover until the 1950’s to ‘60’s
• Tried as a refrigerant
• Used in the production of other chemical agents

Fire Extinguishing Agent

As the use of electricity became more common a replacement was needed for traditional water based and dry chemical agents that were corrosive and presented shock hazards. When found, perhaps by accident, that CT did not conduct electricity or cause damage to electrical equipment or machinery and would put out fires it rapidly became the agent of choice for industry and home. While unknown exactly when carbontet was first used in extinguishers the earliest patent found is dated 1907 and describes carbontetrachlorid(e) in solution with CO2 for use as an extinguishing agent. Over the years other chemicals were added to the mix, some of which were attempts at making the agent less toxic when exposed to high temperatures. These chemical additives help account for labeling on later CT units which state “Not Less Than 25 Percent Carbontetrachloride”.

As with any successful product carbontet enjoyed over 60 years of sales for home and industrial use even though from the 1930’s on it was known to be harmful to humans. In part the continued use was due to the lack of a suitable replacement product that would not harm equipment and was non-conductive..

Replacement Agents

• CB or Chlorobromomethane, another halogenated agent that proved to be more suitable in stored pressure extinguishers because of its low boiling temperature was used between c. 1940 and 1985, but still had similar problems with being toxic when exposed to high temperatures.
• Halon 1211 (halogenated agent) replaced CB as the non-destructive agent of choice and has been in use since the middle 1980’s although production was stopped in the1990’s due to ozone depletion concerns. Like CT Halon 1211 was used by industry as a cleaner which most likely accounted for about 99 percent of release into the atmosphere. Interestingly in 2003 at least one company restarted production in limited quantities for use as a fire fighting agent.
• HalonII, Halotron and other brand names for “safer” halogenated extinguishing agents that began showing up in the later 1990’s have never quite equaled Halon 1211 in performance (pound for pound) or price.

If you have any questions concerning carbontetrachloride or find something in the above writing in error or incomplete please don’t hesitate to contact us.

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