2.2 Machinery spaces and in spaces containing fired processes
2.2.1 In spaces where main or auxiliary oil-fired boilers and other fired processes of equivalent thermal rating
are situated, or in spaces containing oil fuel units or settling tanks, the unit shall be provided with the following:

Interpretation:
1) The fixed water-spray system should cover the entire space instantaneously at release. Even though the
fixed water-spray system can by definition either deluge, sprinkler or a water mist system, this excludes
sprinkler systems.
2) The quantity of the dry material should be at least 0.1 m³.
3) A suitable shovel for spreading the dry material should be available.
(as based on SOLAS II-2, 10.5.1.2.3)
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7.3.5.1 Deluge Systems
A deluge system is a fixed fire protection system in which the pipe system is empty of water and
kept pressurized with dry air, until the a fire condition is detected and the deluge valve is operated to
distribute pressurized water to the nozzles or sprinklers directing the water onto the protected
object(s). Various types of sensors can be used in the detection systems. The common ones include
sensors for detection of: heat, smoke, infrared and/or ultraviolet radiation. Some common types of
detection sensors use a low melting point material at the spray nozzles, where the melting of the
sensor causes a loss of pressure in pipe downstream from the deluge valve. The loss of downstream
pressure causes opening of the deluge valve and activation of the deluge system. Other types of
activation can also be used. The dry pipe system also allows this system to be used in areas where
sub-zero temperatures occurs.
Deluge systems are typically used where quick application of large quantities of water is required to
control a fire and protect high value adjacent assets, such as on generator and unit transformers in
power stations, bulks supply transformers at industrial plant and major transmission or substation
transformer in city locations. The deluge system can quench a fire externally to a transformer by
cooling the fire and the fuel and also by reducing the oxygen available for the combustion. It can also
cool the transformers tank, oil pipes and the cooler bank to prevent rupture form being caused by the
fire and possible against explosion caused by heat from the fire. It does not prevent tank rupture
caused by internal arcing from the initiating fault. Figure 53 shows a typical water spray arrangement
for a transformer and its oil containment area in a diagrammatic presentation.


Deluge system requires a large volume of water NFPA guidelines states 10.2 l/minute/m2 for a
deluge system for transformer fire protection. This means that the water must be available and the
delivery system must be designed to deliver this quantity at the required pressure. The drainage/oil
separation system must also be able to handle the large flow of water from such a system. However,
it may be possible to reclaim and re-use of the water for ongoing fire fighting, if an effective oil- water separation system has been implemented as part of the design.

Figure 54: Water spray system with rock filled pit
Figure 54 shows a water spray system being tested on a transformer.


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Note added at 29 mins (2017-09-04 08:50:34 GMT)
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