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Fire fighting equipment for machinery spaces - Automatic water spray system
Fire protection on ships is provided by detection and fire-fighting equipment together with structural features which are intended to contain an outbreak of fire and the employment when required of non-combustible materials to prevent its spread.
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.
The accommodation areas are fitted with sprinkler heads which both
detect and extinguish fires. The sprinkler head is closed by a quartzoid
bulb which contains a liquid that expands considerably on heating
(Figure ). When excessively heated the liquid expands, shatters the
bulb and water will issue from the sprinkler head.
A deflector plate on
the sprinkler head causes the water to spray out over a large area.
The water is supplied initially from a tank pressurised by compressed
air (Figure below). Once the tank pressure falls, as a sprinkler issues
water, a salt water pump cuts in automatically to maintain the water
supply as long as is necessary. The system is initially charged with fresh
water to reduce corrosion effects.
Fig: Sprinkler head
The complete installation is divided into several sections, each containing
about 150 to 200 sprinklers and having an alarm valve. When one or
more sprinklers operate water flows through the section valve and
sounds an alarm and also provides a visual display identifying the section
containing the fire.
In the machinery space the sprinkler heads are known as 'sprayers'
and have no quartzoid bulb. Also the section valves are manually
operated to supply water to the sprayers (Figure above). The system is
pressurised by compressed air with a salt water pump arranged to cut in
automatically if the pressure drops. The accommodation and machinery
space systems may be combined by a valve which is normally kept locked
The system should be regularly checked by creating fault conditions at
the various section control valves by opening a test valve, and checking
for audible and visual alarms.
Fig: Automatic water spray system
Water mist (Fog)
Water mist (fog) sprinklers are being used as an alternative to, the now
banned, Halon fire suppression systems. The mist system delivers very
small water particles, which are able to remain suspended in the air. The
water particles are evaporated by the heat of the fire and the expanding
vapour displaces oxygen. The combined cooling and oxygen starvation
effects quickly extinguishes a fire. Less water is used than with sprinkler
systems and the mist has proved effective against liquid fuel fires, making
it suitable for use in machinery spaces.
Research is continuing, in particular as to the effectiveness of mist in
a large machinery space. Water mist is accepted as a fire extinguishing
agent, with respect to SOLAS fire protection requirements.
Types of portable fire extinguisher
There are four principal types of portable extinguisher usually found on
board ship. These are the soda-acid, foam, dry powder and carbon dioxide
extinguishers. Details as below :
- Soda acid portable fire extinguisher
The container of this extinguisher holds a sodium bicarbonate solution.
The screw-on cap contains a plunger mechanism covered by a safety
- Foam type portable fire extinguisher
The main container is filled with sodium bicarbonate solution and a long
inner polythene container is filled with aluminium sulphate
- Dry powder fire extinguishers
The outer container contains sodium bicarbonate powder. A capsule of
carbon dioxide gas is located beneath a plunger mechanism in the
- CO2 portable fire extinguisher
A very strong container is used to store liquid carbon dioxide under
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.
Other important fire & safety equipments
- Fire main system for cargo ships
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....
- Automatic water spray & water mist system for machinery protected area
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. ....
- Automatic foam induction system for machinery space fire
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. ...
- CO2 fire extinguishing installations for machinery spaces
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 gas systems, inert gas generator
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. ....
- Fire fighting Halon system
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. ....
- Use of Breathing apparatus
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.
- Emergency Fire pump cargo ships machinery spaces
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 adapter for machinery space fire
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.
- Various fire detectors working principle
The main function of a fire detector is to detect a fire
as quickly as possible; it must also be reliable and require a minimum of
- Fire detection system
The fire detection system is to be classed as Critical Equipment and must be maintained in good working order.
- Fire fighting strategy for cargo ships
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.
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