Water mist as fire extinguishing medium is gaining ground and shows to be very effective in fighting and controlling fire when the system is correctly dimensioned and adjusted to the area of application. Water mist is not suited for general use. An incorrect dimensioned water mist system or incorrect use of water mist gives poor extinguishing result.

When using water mist systems as fire extinguishing medium on board ship, IMO demand documentation by laboratory tests that such installations fulfil the requirements. Testing and approval of water mist extinguishing installations is performed in scale 1:1.

The effectiveness of water mist gets poorer when the room volume increases. For machinery space on board ship the tendency is that water mist system are applied in increasingly bigger rooms. During 1998, SINTEF NBL set new record twice when starting off using water mist in 1000 m³ and 1800 m³ engine rooms respectively.

The largest IMO approved machinery space on board ship using water mist as extinguishing medium tested by SINTEF NBL, is now 3348 m³ with 10,1 m headroom.

SINTEF NBL is now starting to test according to IMO 1165.