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MSC/Circ 913 Test Protocol

MSC/Circular 913 contains the IMO Guidelines and test procedures for the approval of fixed, water-based, local application, fire-fighting systems for use in Category A machinery spaces and Scotch Mist has been tested against this rigorous standard.

The enclosure used for carrying out the tests is a massive 10 metres square with an overall height of 6 metres. It is sufficiently large and provided with adequate natural ventilation during the fire test to ensure that the oxygen concentration at the fire location during tests remains above 20% without activation of the local application fire-fighting system. The fire scenarios consist of nominal 1 and 6 Megawatt spray fires, produced using light diesel oil fueled by pressurised diesel jets.

The tests are intended to evaluate the fire-extinguishing capabilities of individual nozzles and grids of nozzles used as local application fire-fighting systems on light diesel oil fuel spray fires. The tests also define the following design and installation criteria:

  • Maximum spacing between nozzles
  • Minimum and maximum distance between the nozzles and the protected hazard
  • The need for nozzles to be positioned outside of the protected hazard
  • Minimum and maximum operating pressure.

The local application system consists of uniformly spaced nozzles directed vertically downward using a 2 x 2 nozzle grid, installed 1m below the ceiling of the enclosure, the maximum spacing of the nozzles being in accordance with the Scotch Mist design and installation manual.

The fire-extinguishing capabilities of the system are evaluated for minimum and maximum separation distances (the distance between the nozzle grid and the fuel spray nozzle), as defined in the Scotch Mist design and installation manual. Each separation distance is evaluated against the two fire scenarios (1 and 6 MW spray fires).

Tests are conducted with the fuel spray nozzles horizontally positioned in the following locations: 

  • Between four nozzles
  • Under one nozzle at the edge of the grid
  • Between two nozzles at the edge of the grid.

The local application fire-fighting system is required to extinguish the test fires within 5 minutes from the start of water discharge. If the fire re-ignites after this five minute water discharge period, the test is considered to be a failure. Scotch Mist extinguished the test fires within the prescribed time, many within a matter of seconds, obtaining a PASS result for all tests. 


Test Protocols