Watermist fire fighting MV electrical safety

lyledunn: 
 

I hope you make yourself available to your local ET a branch, David. I could see you delivering a vey interesting technical walkthrough of your new vessels!

As an aside, are shore connections completely out of the question as an alternative to lugging big batteries every trip?

You'd need a very long extension lead to get all the way from Dover to Calais ?

Hi Simon, more than happy to deliver a walkthrough of the new Hybrid Super Ferries we are building. Let me know when and where and will be happy to present.

Re shore connections, big debate here as the current philosophy is to let cruise ships connect to an HV shore supply for the duration of their stay ( usually 12 hours) to reduce pollution i  the port area. They all need roughly 6-10 MW so having 75-120 MWH of batteries on board is not practical …think 1500 EV cars worth!

The shore connection is called ‘cold ironing’ and there are a few ports providing 1 or 2 berths with these connections to cope with 11KV and 6.6KV cruise ships. Its not practical for a ferry with a 1-2 hr turn around to connect up as connection and disconnection can take 20mins for each task . Cost is another issue,  KWH costs via cold ironing are significantly more than a KWH raised with MGO ( Marine gas oil) on the ship so the driver is an environmental one not economic as most ships DG's are more efficient (cost wise) than shore power.

Simon Barker: 
You'd need a very long extension lead to get all the way from Dover to Calais ?

It's called Interconnexion France-Angleterre!

LOL, indeed! Bet we'll need a continental adaptor as well…..Calais are in the process of setting up cold ironing capability in their new port ( 2025?) Dover is still in planning. Southampton will have their first cold ironing equipped terminal in 2022 with their new terminal. Not sure re others in the UK bit its being rolled out ahead of 2030 emission changes.

I have only installed water mist system electrical supplies in domestic properties, the actual water mist equipment being installed by a fire alarm company with a release head under the base of the kitchen tap and another on the wall of the room the stairs come down into.

The guys who installed the actual equipment assured me that it doesn’t drench everything and would not get into electrical fittings and ruin everything in the rooms, it would all merely require a wipe down afterwards.

But I have never seen one go off or the aftermath, mind you I was careful about where I ran the cables too for the heat alarms that activate the system.

The domestic systems can operate from a tank of water about the size of a storage heater, so they don’t have an unlimited water supply, the systems connected to the water main only run for a limited time, it’s not like a  car wash.

David Gorshkov: 
 

Not sure re others in the UK bit its being rolled out ahead of 2030 emission changes.

Indeed, Boris wants all ships to be Hydrogen powered by 2030. Hope you're prepared for that!

I was involved in a trial of water mist spray in computer rooms and LV switch rooms back in the mid 90s, after Halon was withdrawn. I don’t recall the manufacturer, but I do remember that a demo was arranged with IBM, which left everything working while the water was set off, and afterwards too. At the time, we were looking at an in-building system that was more survivable (for staff) than CO2 was. Later, water mist replaced CO2 in EHV substations, again, as it was survivable if it was inadvertently set off. 

Regards,

Alan. 

Hello Alan, this is very helpful indeed. I'm trying to risk assess the IO rating of the MV equipment in the space protected by the water mist FDS and need to validate the damage potential to IP32 equipment as well as the safety risk to any water pools that develop during any discharge. You don't recall if there was any standards involved with the water mist and testing of potential conductive paths etc?? Appreciate the feedback which helps with this task. Dave

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.

Great feedback Alasdair, still cant find a definitive study on the testing though! Definitely recall QM2 HF fire..looked after her as Electrical Superintendent for a few years. We also had an issue on Ventura with a steam leak in the PEM/Convertor room…that goodness they were Ip44 cabinets! Yep, IACS call out IP44 for FFFA systems