Ans. The scavenge space to be
permanently connected through an approved fire extinguishing system, entirely
separated from the extinguishing system of the engine room.
When the scavenge space is connected to the under side of
the piston, there is every possibility of scavenge fire if the blowpast of the
hot exhaust gas takes place due to worn out cylinder liner or broken piston
rings or piston ring cut off in the groove. In such circumstances, the hot
gases or the spark, entering the scavenge space, will start burning the sludge
and accumulated oil inside the scavenge space. As plenty amount of air is
available this scavenge fire may continue for a longer period and it may also
go beyond control. Hence it is necessary that a permanent arrangement must be
provided so that if all other means, such as stopping of the engine and
covering the exhaust and the turbocharger suction filter with a cloth, fail. In
such circumstances, it should be possible to extinguish the fire by the use of
a permanent extinguishing medium which is connected to the underside of the
piston scavenge space mostly CO2 or steam is utilized. The requirement for this
is very small and it should be independent of the engine room system because if
it is connected to the engine room fire fighting system, it may possible that
you may discharge the complete safe battery of the cylinder which are actually
kept for the engine room fire. In such condition, engine room fire fighting
equipment capacity will be reduced. Hence the scavenge space fire fighting
installation should be entirely independent of the engine room fire fighting
installation.