Class L Fires: The Hidden Danger of Lithium-Ion Batteries – And the Extinguishers Built to Stop Them

 Class L fires were formally introduced in the January 2026 edition of ISO 3941:2026 to address a growing global risk: lithium-ion battery incidents without metallic lithium. This classification recognises that lithium-ion battery fires behave differently from traditional fire classes (A, B, C, D and K) due to their electrochemical characteristics and thermal runaway potential.

Lithium-ion batteries power electric vehicles, e-bikes, laptops, power tools and energy storage systems. While efficient and compact, their high energy density can result in rapid escalation, toxic emissions and re-ignition risks. For businesses and property owners assessing Fire Extinguishers Perth suppliers, understanding Class L risk exposure is now essential.

Standard ABC extinguishers may assist with small, post-runaway fires by treating them as Class A combustion (burning plastics). However, active lithium-ion battery events require specifically designed Class L Fire extinguishers.

Why Lithium-Ion Fires Are Different

Lithium-ion battery fires are driven by thermal runaway — a chain reaction where overheating in one cell can trigger adjacent cells. Internal temperatures may reach approximately 900°C, with external fire temperatures exceeding 1,000°C.

Unlike conventional fuel-based fires:

• They generate their own oxygen.
  
• They can reignite hours or days after suppression.
  
• They emit toxic gases including hydrogen fluoride and carbon monoxide.
  
• They may produce explosive hydrogen when water reacts with internal components.
  
• Cell rupture can create projectile hazards.
  

The electrolyte components, such as ethylene carbonate, intensify combustion. Suppression often requires significantly more cooling capacity than traditional fires.

Components Present in Class L Fire Extinguishers

Class L extinguishers are engineered for controlled cooling and encapsulation of battery materials. Typical components include:

• Cylinder: Stainless steel construction (SUS304 or SS316) for corrosion resistance and durability, available in capacities ranging from 1L to 50L.
  
• Extinguishing Agent: Water-based agents with additives such as Aqueous Vermiculite Dispersion (AVD) or fluoride-free formulations designed to create a heat-resistant barrier over battery cells.
  
• Delivery System: Flexible hose, pressure gauge and nitrogen propellant for directed application.
  

These extinguishers are often compatible across multiple fire classes, depending on formulation. Organisations sourcing Fire safety Equipment Perth providers should confirm compatibility and certification status before deployment.

Why Fluoride-Free Formulations Matter

Modern Class L extinguishing agents increasingly avoid fluorinated compounds such as PFAS and PFOS, previously common in AFFF foam systems. These substances raised environmental and health concerns due to persistence and bioaccumulation.

Regulatory developments have accelerated the shift:

• EU restrictions prohibit placing PFAS-containing extinguishing foams on the market from October 23, 2026 (with limited transition allowances).
  
• SOLAS maritime amendments ban PFOS-based fire media from January 1, 2026.
  
• Global workplace regulations are encouraging fluorine-free alternatives.
  

Fluoride-free formulations are water-based or foam-based systems designed to cool battery cells, reduce vapour release and minimise re-ignition potential.

Fire Safety Perth

Risk Assessment Framework for Class L Fires

Workplaces storing or charging lithium-ion batteries should update fire risk assessments in accordance with ISO 3941:2026 guidance. Key considerations include:

• Battery type, quantity and storage configuration
  
• Charging infrastructure and state-of-charge management
  
• Ventilation and sprinkler adequacy
  
• Emergency response training
  
• Availability of appropriate extinguishers
  

Hazards commonly associated with lithium-ion batteries include thermal runaway, toxic gas release, re-ignition and structural damage from high heat. Severity levels are typically high due to temperature and toxicity factors.

A structured assessment should apply the hierarchy of controls:

1. Elimination or reduction of battery hazards where possible
   
2. Engineering controls such as ventilation and detection systems
   
3. Administrative controls including procedures and training
   
4. Personal protective equipment for response personnel
   

Before purchasing Fire Extinguishers Perth, organisations should verify whether Class L extinguishers hold relevant approvals within their jurisdiction, as certification status may vary.

Operating a Class L Fire Extinguisher

Use the PASS method:

• Pull the pin
  
• Aim at the base of the fire from approximately 2–3 metres
  
• Squeeze the handle in controlled bursts
  
• Sweep across the battery surface
  

If the fire escalates or multiple cells are involved, evacuate immediately and contact emergency services.

Compliance Considerations

Class L extinguishers may not yet carry full UL or NFPA approval in some regions. Businesses must confirm compliance with local fire codes, OSHA guidance, NFPA 855 (where applicable), and local authority requirements before implementation.

Conclusion

Lithium-ion battery use continues to expand across transport, commercial storage and workplace environments. The introduction of Class L fires reflects a necessary evolution in fire classification systems.

Effective mitigation requires updated risk assessments, appropriate extinguisher selection and verification of regulatory compliance. When reviewing Fire safety Equipment Perth suppliers, organisations should prioritise technical suitability, certification status and alignment with emerging standards.