145.05—Classification of fire extinguishers.

(a) Portable and semi-portable extinguishers shall be classified by a combination letter and number symbol. The letter indicating the type of fire which the unit could be expected to extinguish, and the number indicating the relative size of the unit.
(b) The types of fire will be designated as follows:
(1) “A” for fires in ordinary combustible materials where the quenching and cooling effects of quantities of water, or solutions containing large percentages of water, are of first importance.
(2) “B” for fires in flammable liquids, greases, etc., where a blanketing effect is essential.
(3) “C” for fires in electrical equipment where the use of a non-conducting extinguishing agent is of first importance.
(c) The number designations for size will start with “I” for the smallest to “V” for the largest. Sizes I and II are considered portable extinguishers. Sizes III, IV and V are considered semi-portable extinguishers which shall be fitted with suitable hose and nozzle or other practicable means so that all portions of the space concerned may be covered. Examples of size graduations for some of the typical portable and semi-portable extinguishers are set forth in Table 145.05(c).
Table 145.05(c)—Portable and Semiportable Extinguishers
Classification Soda-acid and water, gallons Foam, gallons Carbon dioxide, pounds Dry chemical, pounds
Type Size
A II 21/2 21/2
B II 21/2 15 10
C II 15 10
B V 40 100 50
(d) All portable and semi-portable extinguishers shall have permanently attached thereto a durable name plate giving the name of the item, the rated capacity in gallons or pounds, the name and address of the person or firm for whom approved, and the identifying mark of the actual manufacturer.

Code of Federal Regulations

[CGFR 56-4, 21 FR 903, Feb. 9, 1956, as amended by CGFR 58-28, 23 FR 6880, Sept. 6, 1958]