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Types of Agents—or What’s
Inside the Fire Extinguisher
These are the agents you are
most likely to find on your
average pleasure boat:
Dry chemicals. Can be used on
A, B, and C fires. The label will
indicate which. They are the
most common type for small portable fire extinguishers
found on most boats. All have a B, C rating, which is the
minimum required by the USCG. Some are rated for A, B,
and C, and this is preferred for marine use but not required.
Dry chemicals work by cooling and smothering the fire with
heavy smoke. The powder can be caustic, and if discharged,
effort should be made to completely clean anything the
powder has come in contact with.
Clean agents. Called clean agents because they leave little
or no residue after being discharged. The most common of
these are CO2, Halon and now Halon substitutes. The
Environmental Protection Agency has banned the use of
Halon due to its CFCs. Halon is now being replaced with FE
241, FE 200, HFC-227 and Halotron 1. Clean agents are not
as common in small portable extinguishers as is dry chemical,
but you can find some units that use it. They work by
displacing oxygen in the air, thereby smothering the fire.
The advantage is that they do not leave any residue. The
disadvantage is that because they displace the oxygen, they
are a suffocation hazard when used in confined spaces such
as the cabin of a boat.
Sizes of Extinguishers
Sizes for portable fire extinguishers are set by the U.S. Coast
Guard and use Roman numerals, I being the smallest and V
being the largest. It’s rare to see anything bigger than a size
II on the average-sized pleasure boat.
Size I is 4 to 5 pounds clean agent and 2 to 3 pounds dry
chemical. Commonly this size is not serviceable, meaning it
cannot be recharged should it be used or lose its charge.
Typical onboard B-1 fire extinguishers
Check the label to see if it can
be serviced or not. These are by
far the most common size
found on the average boat.
Size II is 15 pounds clean agent
and 10 pounds dry chemical.
As these units are larger and
more expensive, most (but not
all) are serviceable. Once
again—check your label. Serviceable units can be recharged
by a certified fire extinguisher service center if they lose
charge or are used.
Extinguisher Requirements and Inspecting
The U.S. Coast Guard by law requires all pleasure boats
with engine compartments, and/or with permanently
installed fuel tanks, to carry fire extinguishers. The minimum
number and type are as follows:
16-26 feet: One B-I
26-40 feet: One B-II or two B-I. (Note: A fixed system
equals one B-I.)
40-65 feet: One B-II and one B-I or three B-I. (Note: A
fixed system equals one B-I or two B-II.)
The “B-I” and “B-II” are USCG designations for fire extinguisher
types and sizes. The “B” is based on a complicated
system set up by the USCG and the “I” and “II” are for the
size. Suffice to say, always check the label to make sure it is
USCG-approved. At minimum it should be for B, C fires
with A, B, C preferred.
All extinguishers should be professionally inspected
and tagged at least once a year and a quick visual inspection
done monthly. However, for pleasure boats this is a recommendation
and not a requirement. More often than not, I
find that most boaters rarely do either of these. The USCG
requires you have onboard “approved” fire extinguishers.
This leaves it up to the boat owner to maintain their equipment
in good working order. If you are boarded by the
USCG or local waterway officers, and you have fire extinguishers
that are not fully charged, or are old and in poor
Specializing in Marine SSB
Sailmail / AirMail / Winlink
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Ph: 941.661.4498
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News & Views for Southern Sailors SOUTHWINDS September 2010 41