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CO2 fire extinguishers
Hi All,
I was wondering if anybody around knows the conditions and
limitations of CO2 fire extinguishers usage.
Are they effective outdoors?
Is CO2 lighter or heavier than air?
Thanks.
Suzie
Hi Suzie
CO2 extinguishers are alright on a small electrical
fire indoors, not much use on anything else unless you
have a flooding system installed, then you have to
ensure that a lock off system is employed to allow the
building to be evacuated and to stop suffocating the
occupants. About a 5 to 10% concentration of CO2 is
hazardous. Also beware of pressure rise within the
building if using a flooding system.
Not much use outdoors because of the rapid dispersal
as soon as you stop the application. Can be useful in
kitchens though as there is no clean up required but
staff must be taught never to use it on an oil pan
fire or the pressure of the discharge tends to
splatter boiling oil around and fry them like chips.
CO2 is heavier than oxygen hence the displacement
effect when applied to fires.
You also need to be careful about using it on
materials which can produce or utilise their own
oxygen for example cellulose nitrates or metals such
as magnesium or metal hydrides.
Be a lot better off and easier going with one of the
ABC dry powder types, if it's computer or electrical
equipment it will probably be totalled by the fire
anyway so why worry about the powder getting in.
Hope this helps,
Lee
- although dry powder will blow all over the place if used outdoors on a windy day. CO2 penetrates into equipment much better and is therefore kept near electrical machinery intake cupboards, fuse-boards and the like. It is not recommended for use in confined spaces and is very cold in use.
- had experiance of a member of staff using a C02 extinguisher on a contained waste paper bin fire, not recommended! the result was that most of the office suffered minor scorch damage as the bins contents were blown from the bin by the force of the C02 extinguisher.
This really emphasises the need for information and training in the use of extinguishers. A CO2 was not the best choice for a paper fire in a waste bin - but perhaps it was the only one available? Hopefully the bin was solid metal and so able to contain the fire. A steady stream of water should then have done the job. We used to demonstrate how denying oxygen (in air) to a fire will extinguish it by simply placing a metal tea-tray over an office waste bin with burning paper contents (not in the office!). If available, a fire blanket should have provided a similar result in the case above.
