High Pressure Water Mist (Hyper Mist) System

  • Mandatory in passenger ships with GT > 500 and cargo ships with GT >2000, for fire extinguishing in machinery spaces of category A with volume > 500 m3 (IMO MSC/Circ.913).
  • System introduced as an alternative to the Halon systems (prohibited in 1994) for fire fighting in machinery spaces of category A and cargo pump rooms. This fire extinguishing process is based in 3 mechanisms:
    –  Cooling of the flames
    –  Reduction of the oxygen content by the displacement of the air by the expansion
    of the water vapor
    –  Diminution of the radiating heat
  • The pressurized water in contact with the fire vaporizes and it is converted into steam. This process absorbs much energy lowering the temperature of the fire and the pressurized water expands about 1700 times taking the air away from the fire. These systems require a water consumption 6 to 10 times lower than a traditional sprinkler system
  • It shall be activated automatically by 2 different types of detectors:
    flame and smoke.

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CoC Oral Exam Preparation: (Part – 15): Fire & Safety

Fire Hose:

  1. At least one fire hose for each of the hydrants and hose shall be used only for extinguishing fires and testing purposes. (Passenger Ship)
  2. One for each 30m length of ship and one spare, but not less than 5 in all. (Cargo Ship = or > 1000GT) and ship carrying dangerous goods shall be provided 3 hoses & nozzles in addition to those required above and cargo ship <1000GT, shall be provided no less than 3 fire hoses & nozzles.
  3. 2 ½” diameter and 30ft or 60ft. length.
  4. Nozzle for ER 12mm, 16mm and 19mm size and shall be approved for duel purpose (jet/spray) incorporating shut-off valve.
  5. Fire hoses shall have a length of at least 10 m, but not more than:
  • 15 m in machinery spaces;
  • 20 m in other spaces and open decks; and
  • 25 m for open decks on ships with a maximum breadth in excess of 30 m.

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