Water mist systems are extensively used as fire protection of machinery spaces onboard passenger ships, and have almost taken over as fire extinguishing systems after IMO standardized such systems. Water mist systems are documented through full scale fire testing of the manufacturers' solutions. In practice it has been shown that in spaces with a ceiling height above approximately 10m it is necessary with more water mist nozzles to extinguish low seated fires. The IMO-method that describes the test procedures requires that all nozzles are mounted at ceiling level…