OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at http://www.osha.gov.



June 12, 2000

Mr. Hugh Erwin
115 Wayland Court
Gloucester, N.C. 28528

Dear Mr. Erwin:

This letter is in response to your November 1, 1999, telephone request for written information regarding 29 CFR 1926.150, Table F-1, Fire Extinguisher Data. Specifically, you pointed out that the table appears to be outdated since it lists Soda Acid type extinguishers that operate by turning the extinguisher upside down as an acceptable model/type for Class A fires.

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.

Since they were de-listed, they are not approved and cannot be used to meet the requirements of Subpart F. The inclusion of soda acid and inverting foam extinguishers in Table F-1, Fire Extinguisher Data, is misleading. 29 CFR 1926.150(c)(1)(x) states, "Table F-1 may be used as a guide for selecting the appropriate portable fire extinguishers." The table indicates which type of extinguisher was designed to fight which type of fire. However, it is not a listing of approved extinguisher brands or designs. In this table, soda acid and inverting foam extinguishers are depicted as appropriate for extinguishing Class A and Class AB fires, respectively. While these extinguishers were designed to fight these types of fires, there are no soda acid or inverting foam extinguishers approved by a nationally recognized testing laboratory due to safety problems with these types of extinguishers. Therefore, irrespective of which class of fire they were designed to fight, since no brand of these types of extinguishers are approved, §1926.150(c)(1)(ix) prohibits their use.

When this standard was promulgated, the soda acid and inverting foam extinguishers were already de-listed. We should not have included them in Table F-1; since no such extinguishers met the requirements for approval under §1926.150(c)(1)(ix), it was pointless to indicate in the Table that they were designed for certain classes of fire.

We appreciate that you took the time to bring this problem to our attention. As time and resources allow, we will publish a more useful table.

If you need additional information, please contact us by fax at: U.S. Department of Labor, OSHA, Directorate of Construction, Office of Construction Standards and Guidance, fax # 202-693-1689. You can also contact us by mail at the above office, Room N3468, 200 Constitution Avenue, N.W., Washington, D.C. 20210, although there will be a delay in our receiving correspondence by mail.


Russell B. Swanson, Director
Directorate of Construction

[Corrected 6/2/2005]