Fixed pressure water fire-extinguishing systems
Divided into “water spraying” and “Water mist” types
Both need approval to be used in Machinery space and cargo pump rooms.
Systems are also used in Cabins, ro-ro spaces, vehicle spaces and special category spaces after approval.
Automatic sprinkler, fire detection and fire alarm systems
Sprinkler system is WET pipe type except for small section of dry pipes. Dry pipes need approval.
Passenger ships and cargo ships: need 2 independent sources of power for pumps, detection and alarm systems.
Components:
Sprinklers : normally will operate between 68 deg C to 79 deg C. Locations with high heat shall have them set not more than 30 deg c above maximum deckhead temperature.
Spare heads are carried as per minimum quantity requirements.
Pressure tanks
Volume is at least 2 times the charge needed in 1 minute. Air pressure is used to pressurize tank to maintain working pressure (head of water from bottom of tank to the highest sprinkler). Means are provided to maintain air pressure and replenishing fresh water. Glass gauge is provided for indicating level of water in tank. Means are provided to prevent ingress of seawater in tank.
Sprinkler pumps
Independent power pump, starts automatically when pressure drops in the pressure tank. Capacity of the pump is to supply sufficient water to cover minimum area of 280 sq m at the highest sprinkler.
Pump has a test valve on discharge side to release extra pressure.
System is protected from freezing.
Maximum 200 heads are allowed in 1 section. Each section is isolated by a single valve only. Valve shall be readily accessible and clearly permanently marked. Precaution is taken to avoid unauthorized use.
Test valve is provided near isolation vale of each section for testing automatic alarm for each section.
Sprinkler system has a connection from ships fire main via a non-return valve to prevent backflow from the sprinkler system.
A pressure gauge is provided at each section stop valve and at central section.
Sea inlet is in the space containing the pump. Normally seawater inlet is always open.
Pump and tank are in a remote position from machinery space and NEVER in space which is protected by sprinkler.
Automatic system must be ready all the time and no action by the crew is required. System is always kept charged and has provision for continuous supply of water.
Each section has automatic visual and audible alarm signal given locally and remote. They indicate when system starts operating and/or indicate faults. These remote units are on Nav bridge or other manned controlled station. A switch is provided on Bridge to test alarms.
Sprinklers are placed overhead and give application rate of 5 L/m2/min for protected area.
A list or plan is provided at each indicating unit showing zones and spaces covered in each section. Also instruction are given for testing and maintenance.
Arrangement is provided for testing of the system.