FireNet Community
FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => General Interest => Topic started by: confusedgirlie on September 11, 2007, 09:22:46 PM
-
Hello I am new here and need help with something.
Can any of you tell me what a Vaporising liquid (bfc) extinguisher can and can not be used on and also how to recognise it.
Thanks in advance
CG
-
BCF extinguishers when allowed for general use were a green colour, although I think British Rail may have used yellow, at least in part.
They are now only allowed for use in aircraft and by certain essential users such as the armed forces and the police as BCF is reckoned to be very bad for the ozone layer.
They were designed for use on live electrical equipment, liquid fuel fires (Class B) and could also be used on small wood/paper/furniture fires (Class A) since they discharged as a liquid which rapidly evaporated.
These extinguishers should have been removed from service by December 2003. If you have any of these extinguishers about DO NOT discharge it. Get it removed by an approved disposer for the BCF to be saved and stored for use by the few still allowed to use it.
-
Thanks for the rapid response.
I don't have any about nor have I seen any but it was a question I was asked.
I told them I would find out for a later date and now I can keep my word.
Again, thank you xx
-
Glad to have been of help.
-
Confusedgirlie. Go to this.
http://ozone.unep.org/teap/Reports/HTOC/HTOC94.pdf
-
Thanks for the link, I made it to the Executive Summery and the Consclusion(sic) I will leave reading it to someone else.
-
John is correct. British Rail BCF extinguishers, incidentally were all yellow for 0.7 - 1.5 kg sizes or red with a yellow band for the 5.5 kg size - the yellow band was used to identify extinguishers suitable for live electrical fires and was also found on theit CO2 & Powder extinguishers. The all yellow used on small BCFs allowed the easy identification of stolen extinguishers as everyone elses would be green.
Just to confuse early Pyrene BCF's were grey, London Transport Chubb BCF's black (the black bomb) & Nu Swift Yellow or Golden
Other colour BCF extinguishers (mostly red) are still around in the domestic, motoring & leisure field as were widely used in disposable aerosol type exinguishers, which not being subject to servicing will not have been removed.
Computer & vehicle protection were other key uses for BCF.
If it's really old it could contain other vapourising liquids, all ozone depleting, but also more toxic. I still find red Nu Swift Uni Flash liquid extinguishers (found one last week) often and even the odd black & silver CTC's
-
Don't forget the good old pump action CTC extinguisher which will still be displayed on historic vehicles (usually military), just hope they are empty.
-
Mike,
Re your comments on the old (Pyrene?) pump extinguishers - these can be found in a wide range of places including boats as well as classic vehicles. If I come across these in antique shops I always ask the shop-keeper if it is empty with an explanation about the hazards of CTC; often they are not aware and I am usually thanked - at least to my face! Likewise if I see one on a boat or vehicle I will always query the owner - they are more often aware of the problem than a shop is.
-
Mine is empty and cleaned.
-
go on then enlighten me - what's in a CTC extinguisher and what does it do?
-
Carbon tetrachloride and it makes things shiny. It is a refrigerant really and is hazardous to health.
-
Carbon Tetrachloride (CCl4), a halogenated hydrocarbon in the form of a non flammable organic liquid has special fire extinguishing properties. It was generally less effective than other alternatives from the same era, but being inexpensive was the most popular.
It extinguishes fire partly by the displacement of air when in the form of a heavier than air inert vapour cloud, but mainly by inhibiting the chain reaction of combustion (affinity for free radicals, etc). It's inhibitory factor is 10% (i.e. requires a 10% concentration in air to prevent combustion).
The liquid is clear, heavy, volatile & 5.3 times denser than air & non-conductive, boiling at 77 C.
To be effective the liquid must vapourise in the fire zone & the hand pumps suffered from discharge in a jerky solid jet, with most CTC running off without vapourising - CTC was best discharged as a spray dissolved & propelled by CO2, a method pioneered in 1911 by Read & Cambell using sparklet bulbs ('Petrolex') in the followed in the 1920's by J.Blakeborough (later to form Nu-Swift) who pioneered stored pressure charges. Despite this pump extinguishers were still widely manufactured into the 1960's with the Pyrene Company of Delaware pioneering the use of CTC with their first pump in 1907.
CTC was widely used as a degreasing & dry cleaning solvent and theft from hand pumps was not unknown with large users like the War Department adding a pink dye to the liquid to deter theft for cleaning of clothing.
CTC was narcotic & its by products when used on fires were equally dangerous in some cases Phosgene was formed, a gas used as a weapon in World War 1
In the 1930's & 40's Methyl Bromide was developed by the National Fire Protection Company and gave CTC a run for it's money being adopted by widely by the Air Ministry for portable & fixedmilitary planes and electricity boards for fixed systems in substations as it had a far lower inhibitory factor of 4. It rapidly fell out of favour due to it's prohbitive cost & the key property of MB that made it an excellent choice in ship fumigation.....
The Third Reich provided the next step in vapourising liquid technology by developing ChloroBromoMethane during World War 2, the technology being initially seized by the US and filtering through to the UK by the mid 1950's via Nu Swift. Although more expensive than CTC it was less toxic & more effective with an inhibitory factor of 6.2.
The early 1960's saw an advance in the UK when Nu Swift developed a blend of 111 Trichloroethane & ChloroBromoMethane (80%/20%) branded Uni Flash liquid, being a cheaper alternative to CBM whilst retaining low toxicity and a good inibitory factor.
The end of the 60's saw ICI develop the vapourising liquid we all know, Bromochlorodifluoromethane, and BCF's handy properties ensured it's place in the forefront of fire fighting for the next 30 years & if it wasn't for the environmental concerns it would still be used widely today
-
Has anyone ever sat down and calculated the damage to the environment from an uncontrolled fire as compared to one quickly extinguished but with 1.5kg of BCF?
-
In my earliest career trying to earn a living fixing tvs ( I broke more than I fixed- bit like my fire service career) the old engineers swore by CTC as a switch cleaner. But it was very toxic and occasionally there were fatalities when careless engineers inhaled too much vapour - they just died suddenly a couple of weeks later if I recall.
-
Has anyone ever sat down and calculated the damage to the environment from an uncontrolled fire as compared to one quickly extinguished but with 1.5kg of BCF?
Fairish point John but I would think the Montreal Protocol is more political tokenism than anything else. If the politicians were really that concerned about the environment they would have had the summit by video conferencing rather than spewing goodness knows what out of the tail pipes of the numerous Boeings getting them and their hangers on there.
Mind you video conferencing means no 4 star hotel, condon bleu cuisine or somewhere for the wife or husband to get freebe goods on the backs of their free loading spouses.
-
Nearlythere,
Quite! It irked me considerably when I worked at the Fire Research Station that our political masters in the then DoE just said "No more BCF." No consultation with their experts (ie us) and not even the opportunity for us to suggest that there could be a slightly different viewpoint on the subject.
-
V.interesting AnthonyB.thankyou.
-
The montreal protocol was about protecting the Ozone layer - global warming hadn't got into the limelight at that time.
There were/are alternatives around that didn't cause the same problems so it makes perfect sense that they were taken off the shelves. Of course CO2 is still in use????
-
Of course whilst good old Europe stopped the use of BCF et al except for special risks* it's still produced and used in India & the Middle and Far East.
The USA still uses it, although they are catching up & using alternatives, despite some alternatives such as Halotron being banned over here as still too damaging
*In hand held fire extinguishers and fixed fire extinguisher equipment for engines for use
on board aircraft
• In aircraft for the protection of crew compartments, engine nacelles, cargo bays and
dry bays
• In fire extinguishers essential to personal safety used for initial extinguishing by fire brigades
• In military and police fire extinguishers for use on persons
-
You should write a book. Come to think of it - its easier to ask you.