Page 264 - Introduction to Marine Engineering

Fire fighting and safety 239

The carbon dioxide extinguisher is tested to 207 bar initially every 10
years and after two such tests, every five years. The dry powder
extinguisher is tested to 35 bar once every four years.
Most extinguishers should be tested by discharge over a period of one
to five years, depending on the extinguisher type, e.g. soda-acid and dry
powder types 20% discharged'per year, foam types 50% discharged per
year. Carbon dioxide extinguishers should be weighed every six months
to check' for leakage.
Where practicable the operating mechanisms of portable extin-
guishers should be examined every three months.
Any plunger should be checked for free movement, vent holes should
be clear and cap threads lightly greased. Most extinguishers with
screw-on caps have a number of holes in the threaded region. These are
provided to release pressure before the cap is taken off: they should be
checked to be clear.

Fixed installations
A variety of different fixed fire fighting installations exist, some of
which are specifically designed for certain types of ship. A selection of
the more general installations will now be outlined.

Fire main
A sea water supply system to fire hydrants is fitted to every ship (Figure
13.8). Several pumps in the engine room will be arranged to supply the
system, their number and capacity being dictated by legislation
(Department of Transport for UK registered vessels). An emergency fire
pump will also be located remote from the machinery space and with
independent means of power.

Forecastle deck
Accommodation hydrant
deck hydrants

Booster _c»Ol
pump I MJMJ

Figure 13.8 Fire main