Extinguishers for traction battery recharging facility

[SeaBass]

I've recently been to a facility which has a large number of battery operated fork trucks and vehicles in a ware house environment. Within the ware house is a large traction battery recharging facility. The batteries, which are the sealed type as opposed to lead acid,  are removed from the vehicles and swapped for a recently recharged unit. The flat batteries are then placed in a rack where they are recharged.

The current fire extinguisher provision in and around the charging bay is dry powder, quite a few of them. I know that DPs are not recommended for use indoors, however, they are effective and safe for use on high voltages.  I see no significant life safety risk with the current provision, but wondered whether others would recommend their removal and replacement with CO2 or an alternative.    After all, if one of the batteries did catch fire, the plastic battery casing that would be the primary fuel involved and a CO2 would not be particularly effective on such a fire .     

[Tom Sutton]

Is the charging unit in an enclosed area or the open warehouse and would the discharge of a powder extinguisher cause a sudden reduction of visibility, which could temporarily jeopardize escape, rescue or other emergency action. In an enclosed normal room I can see a problem but in an open warehouse would there be a problem?

[SeaBass]

It's in a corner of the warehouse, Tom. And yes, a sudden reduction of visibility could be an issue, but I don't think it would be a significant one. I'm wondering if DP, despite the potential visibility and respiratory issues, is the better and more effective extinguisher, on the basis that CO2 has poor cooling effect and the battery casings would be the primary fuel load, but there is a live and significant electrical hazard.

[kurnal]

Would the acidic powder cause consequential losses to the stock or to the MHE? In my experience this consideration has ruled against the use of DP in these situations

[AnthonyB]

Powder can be used indoors subject to a suitable H&S assessment. The likely occupancy of the warehouse and it's open high roof nature lend themselves to making the personnel safety aspect less of a concern than in a more enclosed area, public building or premises with vulnerable occupants.

So assuming we have ticked the box on that front you just need to satisfy that it is suitable for the risks and preferred in this situation based on it's multi-class cover, need for less different types of unit and particular efficacy on the materials involved.

If these boxes are ticked only the secondary damage potential needs to be overcome. If the possible damage is tolerable in relation to all the advantages above then go for it. Remember it's acidic, fluxes and sticks to warm surfaces, and can cause fatigue in aluminium and advanced corrosion in other metals - but if you have good business continuity arrangements to clean up quickly and appropriately it won't be as bad as it could be.

Powder in this case wouldn't be unreasonable, CO2 is an option but you would probably need 5kg units and they wouldn't have the advantage of D/P. If you want to think out of the box there is Triclass & Water Mist.

[Tom Sutton]

A further consideration would be the means of isolating the supply to the charging units which should be close, but not too close as to prevent accessing the isolation switch, if involved in fire. Signage would be important indicating the first action should be isolation the supply  and the location of the isolation switch.

[SeaBass]

Thanks Gents, some interesting points for consideration.