The L2 powder fire extinguisher is the most recommended fire extinguisher in the Class D Specialist Powder class, specifically for extinguishing burning lithium metal fires. Whilst the L2 is a specialist fire extinguisher for tackling Class D metal fires, more and more sites are claiming that they are also highly effective on lithium-ion battery fires and this is not necessarily correct.
The L2 fire extinguisher is a graphite powder extinguisher. In the case of magnesium it is designed to smother the fire by covering over the magnesium in the same way that it could be covered by a dry sand.
The graphite has good thermal conductivity, so it helps to remove the heat whilst reducing the amount of oxygen available for the magnesium to burn. However, it does not provide an active coating since it does not form an impermeable layer unless you use a considerable amount, which is not generally the case.
L2 fire extinguishers can only be applied to a flat surface as the extinguishant has no ability to adhere to vertical or other angular surfaces. Additionally, the delivery is via a short metal tube and so the operator must get very close to the fire in order to apply it and so unless the ideal fire presents itself this product is of limited use.
In short, an L2 extinguisher can help to prevent the spread of the fire but won’t extinguish it, so all the user will be doing is controlling the spread of the fire whilst waiting for it to burn out.
In relation to lithium-ion battery fires, the L2 powder extinguisher has no ability to cool cells in order to prevent the propagation of the fire throughout a module; it cannot easily be delivered to the required location and will not do anything other than transfer a small amount of heat to the surrounding air once applied. Therefore, these extinguishers prove very ineffective against lithium-ion battery fires.
On the other hand, Lith-Ex extinguishers are ideally suited for lithium-ion based battery fires such as those which may occur with personal electronic devices, for example mobile phones and tablets. They can also be used to protect against fires where batteries are under charge, and where batteries are stored, for example goods distribution, battery collection bins, battery recycling locations, public services, battery charging stations and many other scenarios.
The Lith-Ex Extinguisher is compact, lightweight, easy to store, non-toxic and environmentally friendly. It will extinguish uncontrollable flames, quickly cool the excessive heat and prevent re-ignition, something that an ABC powder extinguisher or other liquid-based extinguisher will not be able to do with a lithium-ion battery fire.
How it works:
When a lithium-ion cell goes into thermal runaway (increase in temperature) there are multiple possible sources of heat, for example:
- Combustion – burning of electrolyte, packaging etc.,
- Ohmic – resistive heating caused by high current flow through short circuits,
- Thermodynamic – if the electrodes are no longer isolated then the system will revert to its lowest energy state for that temperature if the activation energy is met,
- Chemical – reaction of the electrode material with other components of the battery (electrolyte), thermal decomposition of the metal oxide electrode, especially cobalt oxide.
In addition to this multitude of mechanisms, the design of the cell often prevents direct access of the extinguishing agent to the source of the fire. Thus, it is difficult to extinguish the fire, permanently cool all the components to below their auto-ignition temperature and prevent re-ignition by delayed reaction processes.
The same comments are also true of the Copper-based Class D units which are designed to cling to vertical surfaces. They will not be effective on lithium battery fires.
For lithium-ion battery fires the best solution is to use a Lith-Ex extinguisher. The Firechief high-performance Lith-Ex extinguishers are designed, tested and manufactured in Europe, ensuring complete control over the quality of this technically advanced product. Together with our technical expertise and support, Lith-Ex extinguishers are a safe and reliable choice.
For more information, go to www.firechiefglobal.com