Tuesday, 26 June 2012

Sprinkler systems

Sprinkler systems
Sprinkler systems
Must be fitted to passenger ships carrying less than 36 passengers in the accommodation spacesand other areas considered necessary be the administration. For pasenger ships carrying greater than 36 passengers it must be fitted to accommodation spaces, corridors, stairwells and to control stations ( the latter may be served by an alternative system to prevent damage). The system must be of an approved type. See below for full requirements.
Generally takes the form of a wet pipe (line continuosly flooded) on to which are connected a number of sprinkler head. These heads consist of a valve held shut by a high expansion fluid filled quartzoid bulb.A small air space is incorporated.
When a fire occurs in an adjacent area to this bulb the fluid expands until the air space is filled, increasing internal pressure causes the bulb to fracture. The size of the air gap determines the temperature at which this failure occurs. The valve plug falls out and a jet of water exits , striking the spray generator where it is then distributed evenly over the surrounding area. In acting this way only the area of the fire is deluged and damage is minimised.

Water is supplied from an air pressurised water tank ( thus the system functions without electrical power), this water is fresh water to minimise damage. The tank is half filled with water and the rest is compressed air at pressure sufficient to ensure that all the water is delivered to the highest sprinkler at sprinkler head working pressure. Once this source of water is exhausted, falling main pressure is detected by a pressure switch. This activates a sea water supply pump. A valve is fitted on the system to allow proper testing of this function. After sea water has entered the system proper flushing with fresh water is required to prevent corrosion
A shore connection may be connected to the system to allow function during dry-dock

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