Fire extinguisher five categories. In the UK the use of Halon gas is now prohibited except under certain situations such as on aircraft and in the military and police. Fire extinguishing performance per fire class is displayed using numbers and letters such as 13A, 55B. EN3 does not recognise a separate electrical class - however there is an additional feature requiring special testing (35 kV dielectric test per EN 3-7:2004). A powder or CO extinguisher will bear an electrical pictogramme as standard signifying that it can be used on live electrical fires (given the symbol E in the table). If a water-based
Chubb Fire 1912–1918 The North Metropolitan Electric Power Supply Company carried out a series of stringent tests on the 'Petrolex' extinguisher and informed Read and Campbell that, 'I have never seen any fire extinguishing appliance that seemed as well suited and effective for dealing with fires in Electrical Stations'. Further patents were granted in France and Brazil during this period. In 1914, foam compound was registered in Great Britain. Read and Campbell introduced their 'Rocsuds' which was an early form of foam extinguisher. The contents were, amongst other things, saponin, derived from the roots of soapwort, sodium bicarbonate, extract of vegetable syrup