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Watermist fire fighting MV electrical safety

David Gorshkov

I am reviewing the fixed watermist fire fighting installations in a new fleet of hybrid ships we are building . The water mist based fixed fire fighting appliances (FFFA) we are using extends into the main propulsion areas as well as the power generating areas.

Water Mist heads are used instead of sprinklers these days as these are more effective, however I can find no definitive tests or regulations that state water mist is safe to use in Medium Voltage switchboard areas?  Appreciate that if I have a fire the main objective is to extinguish it but it is not unusual for FFFA to be set off accidentally in a technical space so I must then consider IP ratings of equipments in these spaces in order that equipment is not damaged during an accidental discharge and that engineers investigating the incident are not at risk of electrocution from the MV systems which may still be live or charged!

Does anyone have any reference information regarding any testing done on Watermist systems to validate their safety levels with LV, MV and indeed HV systems?

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    David,

    There was testing of these systems when they were first introduced onto ships about 20 years ago and the decision was that IP44 was needed in areas exposed to the direct spray. Have a look at the International Association of Classification Societies (IACS - iacs.org.uk) Unified Requirement E20 for Fixed Water Based Local Application Fire Fighting Systems (fortunately abbreviated to FWBLAFFS).

    There has even been a sprinkler system operated inside a high voltage switchboard room on the Queen Mary 2 with no apparent adverse effects, which you can read about in the MAIB (Marine Accident Investigation Bureau) report from about 2009/10 (MAIB Safety Bulletin 4/2010), though I say ‘no apparent’ since the system was activated by the explosion of the 11kV harmonic filters so the area was in a bit of a mess anyway.

    BTW, we will not need a continental adaptor for cold ironing as there are IEC standards for the connections (IEC 80005) and Caledonian MacBrayne are operating hybrid ferries in Scotland which plug in between crossings to partly recharge the batteries, with the Portree-Raasay ferry running purely on batteries on the Sunday crossings due to the reduced sailing frequency.

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    David,

    There was testing of these systems when they were first introduced onto ships about 20 years ago and the decision was that IP44 was needed in areas exposed to the direct spray. Have a look at the International Association of Classification Societies (IACS - iacs.org.uk) Unified Requirement E20 for Fixed Water Based Local Application Fire Fighting Systems (fortunately abbreviated to FWBLAFFS).

    There has even been a sprinkler system operated inside a high voltage switchboard room on the Queen Mary 2 with no apparent adverse effects, which you can read about in the MAIB (Marine Accident Investigation Bureau) report from about 2009/10 (MAIB Safety Bulletin 4/2010), though I say ‘no apparent’ since the system was activated by the explosion of the 11kV harmonic filters so the area was in a bit of a mess anyway.

    BTW, we will not need a continental adaptor for cold ironing as there are IEC standards for the connections (IEC 80005) and Caledonian MacBrayne are operating hybrid ferries in Scotland which plug in between crossings to partly recharge the batteries, with the Portree-Raasay ferry running purely on batteries on the Sunday crossings due to the reduced sailing frequency.

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