Section 1926.150(c)(1)(ix) states that only fire extinguishers listed or approved by a nationally recognized testing laboratory shall be used to meet the requirements of Subpart F pertaining to portable firefighting equipment. Soda acid and inverting foam extinguishers operate by turning the extinguisher upside down, which ruptures the cartridge and initiates an uncontrolled chemical reaction to expel the extinguishing agent. Inverting types of extinguishers were de-listed by Underwriters Laboratories in 1969 (paragraph A-2-2.1.1 in NFPA-10, Portable Fire Extinguishers, 1984 Edition, states that the manufacture of inverting types of extinguishers and their listing by Underwriters Laboratories Inc. was discontinued in 1969).
Information from the NFPA indicates that these extinguishers were de-listed for several reasons. One was the diminishing availability of replacement parts and recharge materials necessary to maintain the extinguishers in a safe and reliable operating condition. Another reason was explained in NFPA's Fire Protection Handbook (18th Edition, 1997 pp. 6-377, 6-378), which provides information on obsolete extinguishers. According to this reference, the manufacture and testing of all inverting-type extinguishers soda acid, foam, and cartridge-operated water and loaded stream was halted in 1969 due to: (1) after 10 to 15 years, many inverting type extinguishers failed to meet the minimum test pressure requirements, and (2) container failures due to blocked discharge elbows or hoses resulted in serious injuries to operators.
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