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It is important that an emergency situation involving fire gets the right kind of relief at the right time. In most of the cases, the emergency response is delayed either due to unavailability of a proper plan or accessibility problems. Keeping these issues in mind, an automatic fire extinguishing system is provided in all the sensitive areas of a ship. This self- activating automatic fire sprinkler system prevents the spreading of fire and helps in maintaining the situation under control.
The sprinkler system consist of a network of sprinkler heads located at dedicated areas, which needs extra protection. The system is generally fixed in accommodation area and machinery spaces. The sprinkler heads in both these places are not the same, but have certain variations in the equipments used and the method of operation. The sprinkler head is the most important part of the whole emergency system.
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Construction and Working of Sprinkler Head
The sprinkler heads, especially in the accommodation areas can do both the things - detect and extinguish fire. The sprinkler head is covered by semicircular quartzoid bulb, which contains an expandable liquid. A deflector plate is attached at the end of the bulb , which helps in spraying the water over a large area. In case of a fire, the heat causes the liquid inside the bulb to expand, which shatters the bulb, allowing the water to flow from the sprinkler head.
The water is supplied to all the sprinkler heads by means of a tank pressurized with compressed air. The water in the pipes is kept at a constant pressure. As soon as the sprinkler start operating the pressure in the pipe lines falls, a salt water pump cuts in automatically to provide a continuous supply of water. The sprinkler heads are initially provided with fresh water in order to prevent corrosion of the pipeline and the system.
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Not all the sprinkler heads are supplied water by one single pump. The complete installation is divided into sections consisting of 150 to 200 sprinkler heads each, having their own dedicated pumps. All the sections have alarm valves, which provides both audible and visual signal when water water flows through them. This helps in identifying which section of the ship is under fire. An automation system keeps a track of all the sections and is located in the main control room.
The sprinkler heads provided in the engine room are known as "sprayers" and they don't have a quartzoid bulb in their design. There is a different detection system which detects the fire and activates the sprinkler system. The sprinkler system is generally operated manually.
The sprinkler system should be periodically inspected by creating mock situations. Also, the chest valve along with the audible and visual alarms should also be checked for any malfunctioning.
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Bromann, M. (2001) The Design and Layout of Fire Sprinkler Systems 2nd ed. Oxfordshire: CRC Publications