COMPANYNAME M/V “VSLNAME” SOLAS TRAINING MANUAL PART B – Section 8 Fire Extinguishers & Fixed Fire Extinguishing Systems Page 36 of 37
Once a bulb has shattered pressurised water is sprayed into the area of the fire. Initially the extinguishing water is expelled because of the gas pressure being maintained on the system, but immediate loss of water pressure caused by the breaking sprinkler bulb is detected by a sensor which is used start the water pump and flow switches which are used to operate the alarms. The pump delivers water from the storage tank to the sprinkler outlets. Should the fire require more water than is available from the fresh water storage tank there is an automatic charge over to allow the system to take filtered sea water through a sea suction and deliver it via a strainer to the sprinkler system.
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The water supply to any ‘dry’ section in the system is hold back by an isolating valve and the pipework downstream of this is filled with compressed air. If a sprinkler shatters and opens the line the drop in air pressure is detected by a sensor, which is used to open the isolating valve and so allow water to the sprinkler heads. After use the system must be reinstated to its full protective working order. 1. Stop the pump. 2. Drain down any sea water or unclean water that has been introduced to the system. Ensure that the system is clean. 3. Replace spent sprinkler heads by new heads of the same temperature rating. 4. Charge the system and fill the pressure tank to the correct level. 5. Pressurize the system. Deluge systems
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Deluge systems are similar to sprinkler systems except that the pipes terminate in open nozzles. In the event of a fire the nozzles distribute large quantities of water over the entire protected area, not just in a confined location as occurs when the bulb of a sprinkler systems shatters. The water application is uniformly distributed throughout the risk area. Areas that may be protected by deluge systems are ro-ro car decks and tank decks on gas and chemical tankers. The deluge systems are usually arranged in a manner very similar to that described above for the sprinkler system. The system is charged with clean fresh water, kept under pressure, up to the main stop valve known as the deluge valve. The pipework downstream of the deluge valve is dry. The deluge valve may be opened automatically when detectors indicate a fire or it may be opened manually. When the deluge valve is opened the fall in water pressure is detected and system pumps activated. There is a pressurised storage tank and a pump connected to a sea suction similar to the arrangement described for the sprinkler system. On ships carrying liquefied gases in bulk a water spray system for cooling, fire prevention and crew protection in installed to cover: - Exposed cargo tank domes and exposed parts cargo tanks. - Exposed on deck flammable or toxic product storage containers. - Cargo discharge manifolds and the area of their control valves and the area of the other control valves. - Boundaries of the following area facing the cargo area – superstructure and deckhouses normally manned, cargo compressor rooms, storerooms containing high risk fire items, cargo control rooms.
The system on ships carrying liquefied gases in bulk is to uniformly distribute water spray on horizontal surfaces at a rate of at least 10 l/m2 per minute and on vertical Issue No. 1
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