Chapter 18: Bilge Systems, Fire Mains, and Fire Extinguishers
HALONREPLACEMENTS As noted, Halon has been banned to preserve the ozone layer
(though it may still be used on existing installations). The common replacements for Halon are
- CO 2 (carbon dioxide):It is good for B- or C-class fires but not so effective on A-class
fires. It doesn’t leave a residue or damage electric components. - FE-241 (chlorotetrafluoroethane):Probably the most common Halon replacement
other than CO 2. It is toxic if inhaled, though it leaves no residue. It is suitable for unoc-
cupied compartments such as engine and machinery spaces. Good for A, B, and C fires. - FE-227 and HFC-227 (heptafluoropropanes):Common Halon replacements for
occupied spaces because they are nontoxic. Good for A, B, and C fires. - FM-200 (a heptafluoropropane):A fairly expensive Halon replacement. Unlike
FE-241, it is not toxic and is suited to occupied compartments. It is generally a special-
order item, however. Good for A, B, and C fires.
NOTE: Most standard tables for required extinguisher capacity give weight in pounds (or kg)
of CO 2 and pounds (or kg) of Halon required to protect given compartment volumes. Non-
CO 2 Halon replacements, however, are not as effective as Halon. You should allow 50 percent
more weight for the Halon replacement and confirm the quantity with the manufacturer.
TABLE 18-7. ABYC A-4 EXTINGUISHER CAPACITY VERSUS COMPARTMENT
VOLUME
Min. Extinguisher Size Max. Compartment Volume
Agent lb. kg cu.ft. m^3CO 2 5 2.3 66 1.9
10 4.5 133 3.8
15 6.8 200 5.7
20 9.1 266 7.5
Halon* 2.5 1.1 108 3.1
3 1.4 130 3.7
4 1.8 174 4.9
5 2.3 217 6.1
9 4.1 391 11.1
13 5.9 565 16.0
Halocarbon USCG B-I (5.75 lb., 2.6 kg) 108 3.1
USCG B-II (10.75 lb., 4.87 kg) 250 7.0
*Halon discontinued. Add at least 50 percent for Halon substitutes.