CFR

149.405—How are fire extinguishers classified?

(a) Portable and semi-portable extinguishers on a manned deepwater port must be classified using the Coast Guard's marine rating system of a combination letter-and-number symbol in which the letter indicates the type of fire that the extinguisher is designed to extinguish, and the number indicates the relative size of the extinguisher.

(b) The letter designations are as follows:

(1) “A” for fires of ordinary combustible materials where the quenching and cooling effects of water, or solutions containing large percentages of water, are of primary importance;

(2) “B” for fires of flammable liquids, greases, or other thick flammable substances where a blanketing effect is essential; and

(3) “C” for fires in electrical equipment where the use of a non-conducting extinguishing agent is of primary importance.

(c) The number designations for size range from “I” for the smallest extinguisher to “V” for the largest. Sizes I and II are portable extinguishers. Sizes III, IV, and V are semi-portable extinguishers that must 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 149.405.

Table 149.405—Portable and Semi-Portable Extinguishers

Classification type-size	Foam liters(gallons)	Carbon dioxidekilograms(pounds)	Dry chemical kilograms(pounds)
A-II	9.5 (2.5)		1 2.25 (5)
B-II	9.5 (2.5)	6.7 (15)	4.5 (10)
C-II		6.7 (15)	4.5 (10)
B-IV	7.6 (20)	22.5 (50)	13.5 (30)
B-V	15.2 (40)	2 45 (100)	2 22.5 (50)
Notes:
1 Must be specifically approved as a type “A,” “B,” or “C” extinguisher.
2 For outside use, double the quantity of agent that must be carried.

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