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Current affairs Carbon dioxide
Carbon dioxide portables have been around and largely unchanged from their original development in the 1920s, and are still the primary choice for fire suppression where there is live electrical equipment. The loss of the BCF/Halon1211 portable deprives industry and commerce of a very useful multi purpose extinguisher. I can attest to the agent’s effectiveness, as the fi rst real fi re I ever extinguished was in a car engine using an Ministry of Defence 1kg BCF unit at an army show in 1973! Today, despite almost 100 years of
change, the default choice for portable units is largely unchanged: water, foam, dry powder and carbon dioxide. The most signifi cant recent development has been the introduction of the Class F or ‘wet chemical extinguisher’ for fires in fats and cooking oils. The agent in these extinguishers works by saponifying the fat, changing it to soap. The chemical is a strong alkali, for instance potassium carbonate.
It comes as a surprise to me that there is no
real standardised approach to specifying and installing portables. While water units are still the most common, I increasingly fi nd foam and powder units in offi ces and similar locations as apparently the ‘conventional approach’ to distributing portables. When I question the property or facility manager, I’m told that this is what the extinguisher supplier says they needed. I do not understand why in some cases companies are supplying only foam portables and a couple of carbon dioxide units in many properties. What is universal is that small carbon
dioxide units (typically 2.5kg) are also provided close to electrical distribution boards, or in areas where there are large electrical installations. In the absence of a universal agent (such as the much missed BCF), this seems like a reasonable compromise – after all, we don’t want people killing themselves applying water to live equipment – but is the provision of dual units really the answer?
Misleading signage!
Overstated concerns I have long believed that the frequently expressed concerns about ‘mixing water and electricity’ are greatly overstated. Much of the fear may relate to the demonstration of the potential for conduction of high voltage, which used to be regularly displayed at the Fire Service College. However, I can find no records of any actual electrical injuries relating to the use of extinguishers being incurred since 1945. The Health and Safety Executive records
Wet chemical (Class F) fire extinguisher
confirm that, since 1996 (as far back as its records go) none of the fatal electrocutions recorded relate to fi res or fi refi ghting. The fear of electrocution presumably relates to the use of conventional, nine litre water extinguishers
50 NOVEMBER 2018
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