There may be a variety of different fixed fire fighting installations exist, some of which are specifically designed for certain types of ship.
The sketch shows a sprinkler system suitable for
accommodation purposes. A fire in a one section would
cause a rise in temperature, causing a quartazoid bulb in a
sprinkler head to break, which would then start spraying the
area with fresh water. Once this happens, a flow alarm for
this section will operate giving an alarm on a control panel
that is normally situated on the bridge. This panel will show
the section where the sprinkler head has activated, moulting
in someone investigating the situation. If it is a genuine
alarm, the fire alarm will be sounded, if a false alarm, the
manual stop valve for this section, which will be locked
open, can be shut, the key normally being behind a break
glass panel in the vicinity of the valve.
Fig: Accommodation sprinkler system
The system is always pressurised with fresh water from a
pneupress tank. In the event of a real fire and the pressure
in the pneupress tank falls below a predetermined setting,
a pressure relay will send a signal to the seawater pump,
starting the pump and supplying seawater to the sprinkler
system.
Advantages of the system are:
Its automatic and quick operation,
the fire fighting medium is cheap and plentiful
and the system is also easily tested.
Disadvantages are:
It causes a lot of damage when used.
Danger of free surface effect if a lot of water is used
high up on the accommodation decks.
System has to be flushed with fresh water after use and
a good eye has to be kept on the pressure tank.
Fixed fire extinguishing 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.
An outbreak of fire requires a source of ignition, the presence of combustible material and ample oxygen. Of the three factors, oxygen is provided in large quantities in machinery spaces, accommodation, dry cargo holds and tanker pumprooms by ventilation fans. Air supply trunkings are not only a source for a supply of oxygen to feed the fire but also have potential for carrying smoke from one area to another....
The automatic spray or sprinker system provides a network of sprinkler heads throughout the protected spaces. This system may be used in accommodation areas, and in machinery spaces with certain variations in the equipment used and the method of operation. ....
Foam spreading systems are designed to suit the particular ship's requirements with regard to quantity of foam, areas to be protected, etc. Mechanical foam is the usual substance used, being produced by mixing foam making liquid with large quantities of water. Violent agitation of the mixture in air creates air bubbles in the foam. ...
Fire extinguishing installations employing CO 2 stored under pressure at ambient temperature are extensively used to protect ships' cargo compartments, boiler rooms and machinery spaces. When released the CO 2 is distributed throughout the compartment, so diminishing the relative oxygen content and rendering the atmosphere inert....
Inert gases are those which do not support combustion and are largely nitrogen and carbon dioxide. Large quantities suitable for fire extinguishing can be obtained by burning fuel in carefully measured amounts or by cleaning the exhaust gases from a boiler. ....
A Halon storage system would be very similar to one using carbon dioxide except that fewer cylinders would be required. The liquefied Halon is usually pressurised in the cylinders with nitrogen in order to increase the speed of discharge. ....
Compressed air cylinders are of various sizes, usually of either 9 or 6 litre water capacity.
The fully charged pressure of cylinders also varies. Some types are charged to as high as 300 bar (4500 p.s.i.). The maximum charging pressure is always stamped on either the neck or the shoulder of a cylinder.
Two independently powered pumps must be provided in all cargo ships of 1000 tons gross and over and in passenger ships of less than 4000 tons gross. Larger passenger vessels and passenger ferries must have three such pumps.
Foam branch pipes which operate in a similar manner to those used in deck installations for tankers, are fitted for use with the hydrants in some machinery spaces and in particular for passenger ferry car decks.
A basic strategy should be followed in all fire fighting situations. This
will involve four distinct aspects, which are locating, informing, containing
and finally extinguishing a fire.
Machinery Spaces.com is about working principles, construction and operation of all the machinery
items in a ship intended primarily for engineers working on board and those who working ashore . For any remarks please
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