FIRE CAUSED BY BATTERY CHARGER

[wavecrest]

Good afternoon. My name is Glen and I have a question which I guess would be best directed at Fire Investigations Officers who are members of this site...

My company operates a warehouse facility in Kent. Last year we had a very serious fire at one of our warehouse units which took several days to put out (the warehouse was mainly storing paper goods). Fortunately the fire was at night so there were no injuries to staff. Unfortunately the building was completely destroyed.

It would appear that the cause of the fire was failure of a battery charger which was being used to charge an electric fork lift truck overnight.

My question is whether any members are aware of similar cases they have investigated/attended where a fork lift battery charger has caused a fire?

I am trying to find out how common this type of fire is in the UK and evidence of similar incidents to ours.

Any information would be useful as the company which supplied the battery charger are trying to deny responsibility although all the evidence turned up so far clearly points in their direction!

Thanks in advance.

[kurnal]

People always deny responsibility. You will have to prove their negligence to win this, to estabish that they had a duty of care, that they were in breach of this duty and how, and that the fire occurred as a result.

Where did the fault arise? In the charger, the battery, the wiring to the charger or the protective systems? Was the system properly maintained? I see so many of these things in a poor condition through misuse and neglect- chafed and crushed leads, missing grommets, poor connections. Its a wonder theres not more fires. Some of these things charge at huge currents but very often are intelligent and monitored.
Was a fire investigation carried out at the time?  Have you a copy of the report? Why do you think the manufacturers are responsible- can you show the electrical systems and protective devices were in good order?

[afterburner]

Hi Glen, the post from Kurnal addresses all the issues on this incident. The frequency of an event is not an indicator of a universal cause. No matter how many fires are attributed to fork lift truck battery chargers, the same considerations apply.   
The source of ignition may be traceable all the way back to the battery charger. But was the battery charger actually at fault? Can you be sure that the charger was tested and maintained within the manufacturers specifications? Was it used as it should be, or were there 'habit and practice' departures from correct use?
Do you know what component actually failed within the charger? Was this due to a design fault, poor manufacture, lack of maintenance etc?
Without being able to answer these questions to show that the fire was caused by propely maintained and correctly used charger you might have a real struggle to prove liability 

[Chris Houston]

I'd say that battery charging is a common cause of fire in industrial premises.  I can think of 1 fairly recent example at a client's premises in the UK.

[afterburner]

Quite agree Chris that the process of battery charging is a hazard recognisable as a start point for fires.

But what we were trying to clarify is what went wrong within the process. If the battery charging process is successfully carried out a number of times without a fire as a result, what is the actual 'event' that changes battery charging into ignition? The deeper cause could be a number of things, from various faults to operator error.

[Chris Houston]

Quite agree Chris that the process of battery charging is a hazard recognisable as a start point for fires.

But what we were trying to clarify is what went wrong within the process. If the battery charging process is successfully carried out a number of times without a fire as a result, what is the actual 'event' that changes battery charging into ignition? The deeper cause could be a number of things, from various faults to operator error.

Of course, lots of things could have gone wrong.  Battery charging creates hydrogen gas.  Combination of a spark igniting gas and combustibles being in the wrong place at the wrong time would be the most common scenario.

Risk controls of ventilation to prevent gas building up, electrical maintenance to avoid sparks and removal of combustible items from withing x metres from charging point would all be good idea, obviously a bit late to make suggestions.

[BLEVE]

In reality battery charging activities should be segregated from all other combustible materials. My preference is either to sepaate with consruction offering Fr 60 minutes or separate by distance to reduce Radiant Heat below 20 KW/M^2

[nearlythere]

or separate by distance to reduce Radiant Heat

Hello Bleve
How does one determine the distance  necessary to reduce the radiant heat to below 20 KW/M^2?
What equipment does the average electric forklift truck owner need to buy to do the necessary measuring to ensure that the distance is sufficient?

[Meerkat]

In the reality I have experienced, battery charging areas tend to get pushed into a corner of the factory or warehouse.  They certainly don't have fire resisting separation in most of the premises I have seen and the distance separation has more to do with making sure there's enough room to safely manouevre the trucks in and park them without anyone else hitting them while driving by than it does with radiant heat output!

[BLEVE]

Nearly there,

You take into account the following:

Peak Heat Release Rate of the lift truck & charger
% of combustion energy lost by flame as radiation
distance from flame axis to target fuel source


Assuming an overly conservative PHRR of 2000 kW
X_rof 0.6 (high soot content from rubber wheels & plastics)

Distance to 20 kW/m² is 2.2. metres

As you know the 20 kW/m² relates to the piloted ignition of thermally thick materials so it would be better to opt for 10 kW/m² piloted ignition of thermally thin materials and so distance to 10 10 kW/m² is 3.2 metres.

Tools required are PC or calculator and tape measure/yard stick etc.

 

[nearlythere]

Nearly there,

You take into account the following:

Peak Heat Release Rate of the lift truck & charger
% of combustion energy lost by flame as radiation
distance from flame axis to target fuel source


Assuming an overly conservative PHRR of 2000 kW
X_rof 0.6 (high soot content from rubber wheels & plastics)

Distance to 20 kW/m² is 2.2. metres

As you know the 20 kW/m² relates to the piloted ignition of thermally thick materials so it would be better to opt for 10 kW/m² piloted ignition of thermally thin materials and so distance to 10 10 kW/m² is 3.2 metres.

Tools required are PC or calculator and tape measure/yard stick etc.

 

Thanks Bleve. Well explained.
Anyone got a headache tablet?

[Midland Retty]

I feel somewhat inadequate and a bit afraid

Even my calculator has blown up !

[kurnal]

Interesting approach to a common  situation Bleve but is it realistic to expect charging to take place in a segregated area? In my experience in at least 90% of warehouses the charging area is not segregated from the rest of the building.  And in some cases charging is continuous from busbars in the aisles as the truck goes about its business.

I wonder if you apply a quantitative approach to all aspects of your risk assessments or do you tend to use a hybrid approach?  I tend to rely on a qualitative apporach for the majority of my work.

[BLEVE]

Hi Kurnal,
Typically segregation by FR construction is only carried out when requested by insurance underwriters or considered by me in relation to very high value pharma/bio tech product.

I will frequently use a quantatitive approach to either prove or disprove a thesis depending on the task in hand. I tend to prefer quantatitive approach in the majority of my RA, particularly so in the case of fire risk assessment, thermal heat flux, smioke evolution, time to obscuartion and means of escape. 

I like to use a rule of thumb of separating charging activities from combustibles by a distance of at least 5 metres.

[BLEVE]

Meerkat,
It is apparent and widely accepted that lift truck charging operations can and do result in fires. Taking this into account, it is only reasonable that a RA takes into account the likely HRR resulting from the fire and to determine an appropriate separation by distance to prevent the involvement and ignition of secondary fuel sources.

Just because it is normal for these activities to be placed in any available location does not mean that it is correct to do so.