Fire extinguisher CO types have the test information stamped on the cylinder, all other types get a sticker on the back of the cylinder. Once dry, the units are recharged. Unlike the UK, the US does not rebuild extinguishers and replace valves at specific intervals unless parts are found to be defective, with the exception of halon. Halon types are often given new o-rings and valve stems at every internal maintenance to minimize any leakage potential. OEM equipment must be used for replacement parts for the extinguisher to maintain its UL rating. If parts are unavailable, replacement is recommended, keep in mind
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