Rank: Super forum user 
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I have just had an interesting internal email warning of the risk of CO2 Fire Extinguishers causing fires due to the build up of static electricity! Has anybody heard or come across this before?
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Rank: Super forum user 
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I think someone is pulling your chain. I can see no mechanism whatsoever where this would be possible, not even a tenuous one!
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Rank: Super forum user 
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Rank: Super forum user
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It is potentially possible if CO2 is discharged into a confined space containing an unignited flammable/ explosive atmpshpere, but, in my opinion would be most unusual.
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Rank: Forum user
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Not actually causing a fire by virtue of simply being in place; however I think that upon use a CO2 extinguisher can generate static by virtue of the rapid discharge of the CO2.
Therefore they if one were used in a space that contained an explosive mixture of flammable gases or vapours where there is no fire, then an explosion could be caused by any electrostatic sparks generated by the CO2 discharge.
But then again if no fire present then why use a fire extinguisher???
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Rank: Super forum user
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Mr Flibble - you did the right thing by being sceptical about the content of the e-mail you received and sharing it on this forum. It seems that, sadly, too many people simply accept without thinking what they see in e-mails, newspapers and webpages, etc. Hopefully, you intend to politely challenge the e-mail advice about CO2 fire extinguishers soon if you haven't already done so. My guess, for what it's worth, is that it might be difficult to identify the origin of the advice because it probably came as an external e-mail to one or more people in your organisation who simply forwarded it internally without question.
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Rank: Forum user
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The only time I’ve had to be aware of this is in my former career for military aircraft crash rescue. An old technique to gain access to a crashed aircraft cockpit was to use a CO2 to weaken the Perspex canopy by rapidly cooling it and then striking with a crash axe to crack it. One of the potential hazards was a static spark from the discharge of CO2 igniting the fuel vapours from the ruptured fuel tanks.
Whoever thought up this process didn’t do it in anger as it didn’t work anyway (maybe it did with spitfires but I'm not that old)! Those canopies are tough.
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Rank: Super forum user
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firestar967 wrote:The only time I’ve had to be aware of this is in my former career for military aircraft crash rescue. An old technique to gain access to a crashed aircraft cockpit was to use a CO2 to weaken the Perspex canopy by rapidly cooling it and then striking with a crash axe to crack it. One of the potential hazards was a static spark from the discharge of CO2 igniting the fuel vapours from the ruptured fuel tanks.
Whoever thought up this process didn’t do it in anger as it didn’t work anyway (maybe it did with spitfires but I'm not that old)! Those canopies are tough.
Just put a charge through the wiggly line buried in the perspex. That'll do it! ;-)
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Rank: Super forum user
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As mentioned this does seem to be the problem, a static discharged is built up when a CO2 Extinguisher is discharged and there is a risk in a explosive atmosphere, ATEX environment, gas, flammable liquids etc
However my argument is (as previously mentioned) is a) you would only be using it if there was a fire and b) if it was a fire in an ATEX environment or a gas or highly flammable liquid fire, would you not be running away very fast.
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Rank: Super forum user
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Is there any evidence to suggest this could actually happen or is it just a tenuous, theoretical possibility?
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Rank: Super forum user 
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Ahhhhhhhhhhh, if only ALL canopies were fitted with MDC, unfortunately............................
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Rank: Super forum user 
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Rank: Forum user
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Sorry I know off subject but couldn’t resist. MDC another brilliant idea to make it possible to detonate the MDC to gain entry, firefighter releases pull cord (about 500mm long) stands to front and pulls. 2cm thick canopy explodes, pieces of which can travel up to 50 meters in large chunks (it is an explosive charge!) fly in every direction. But the firefighter’s PPE will protect him or her won’t it?
OK CO2 can produce a spark but the LEL will not be reached because of the higher level of CO2 replacing the oxygen.
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Rank: Forum user
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Whilst the link below appears to not be relevant in the case of the OP’s question (unless we are talking about tankers/planes). It does state cases where using C02 to inert a flammable atmosphere may have been the cause of explosions (leading to fatalities). Unless of course the information from the link is not true. http://www.maineoxy.com/...afetips/mar03safetip.pdf
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Rank: Forum user
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Hi Smitch,
The information will be true as it states using it as an inerting agent, nitrogen will do the same but different properties. In each case the CO2 was discharge into an explosive atmosphere where the Lower Explosive Level had been reach so a spark or ignition source was introduced. However, if used in a fire situation the ignition source will already be present and the CO2 will displace the oxygen so combustion can not continue. So using in a fire no problem, using as an inerting agent in an explosive atmosphere - well not a good idea.
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