When a damaged, defective or improperly handled battery enters thermal runaway, it can produce intense heat, hazardous gases, rapidly spreading fire, explosions and repeated ignition. The speed and complexity of these incidents leave little room for improvisation.

That is why more organizations are considering lithium-ion fire blankets as part of their emergency planning. A properly selected blanket may help contain visible flames, reduce radiant heat and limit fire spread, but it cannot be treated as a standalone firefighting solution.

Key takeaways

• Lithium-ion battery fires can involve thermal runaway, hazardous gases, explosions and reignition.
• A lithium-ion fire blanket may help contain flames, debris and radiant heat, but it does not stop thermal runaway.
• Indoor or confined-space blanket deployment may create a deflagration risk.
• Untrained personnel should evacuate, establish an exclusion zone and contact emergency services.

What is a lithium-ion fire blanket?

A lithium-ion fire blanket is a large, heat-resistant containment device designed to be placed over certain burning or overheating battery-powered vehicles or equipment.

Depending on the product, application and incident conditions, a fire blanket may help:

• Contain visible flames and burning debris
• Reduce radiant heat around the incident
• Limit fire spread to nearby vehicles, equipment or structures
• Reduce exposure to smoke while emergency responders manage the incident
• Protect surrounding property until additional response resources arrive

Blankets are available in different sizes and configurations for applications such as passenger vehicles, forklifts, industrial equipment and smaller battery-powered devices.

The product must be selected for the intended application and used according to the manufacturer’s instructions.

What a fire blanket cannot do

A fire blanket should not be described as extinguishing thermal runaway.

Thermal runaway occurs when rising temperatures inside a battery cell trigger a self-sustaining chemical reaction. Heat can then spread from one cell to neighbouring cells. Covering the equipment may control some external fire conditions, but it does not necessarily stop this internal process.

A fire blanket also does not:

• Eliminate hazardous gases
• Remove the risk of explosion or deflagration
• Prevent every possible reignition
• Replace evacuation or emergency services
• Make it safe for unprotected employees to approach a battery fire
• Serve as the only control measure for a large battery or EV incident

The distinction matters. A blanket may help contain aspects of an incident, but containment is not the same as extinguishment.

Blanket deployment can introduce additional hazards

The decision to deploy a fire blanket should be based on the battery type, equipment involved, incident location, stage of the fire and the organization’s emergency response plan.

Recent full-scale testing by UL Research Institutes’ Fire Safety Research Institute identified a potential explosion hazard when fire blankets were used during EV fires with active battery involvement. Its current guidance warns that using EV fire blankets indoors or in confined spaces can present a significant deflagration risk.

This does not mean fire blankets have no role. It means they should not be deployed automatically or without an incident-specific procedure developed with qualified fire-safety professionals.

Recognize the warning signs of thermal runaway

A lithium-ion battery may release heat and hazardous gases before visible flames appear. Possible warning signs include:

• Hissing, popping or other unusual sounds
• White or grey vapour
• A sharp or unusual odour
• Rapidly increasing temperature
• Battery swelling, bulging or deformation
• Smoke, sparks or visible flames

Employees should know how to report these warning signs and when to evacuate. They should not approach, touch or move a suspected battery unless the site’s procedures specifically authorize them to do so.

Hazardous gases may be present before flames appear

Lithium-ion battery incidents can release a complex mixture of gases, vapours and particulates. Depending on the battery chemistry and incident conditions, these may include:

• Hydrogen fluoride
• Carbon monoxide
• Hydrogen
• Hydrocarbon gases and other volatile organic compounds
• Metal-containing particulates

A fire blanket does not make these substances harmless. In some conditions, covering an incident may change how gases accumulate or escape.

Employees without appropriate respiratory protection should remain at a safe distance and follow evacuation procedures. Firefighters and other emergency responders working close to the incident require suitable protective equipment, including self-contained breathing apparatus.

Where appropriate, atmospheric monitoring, thermal imaging and continued observation can help trained responders assess changing conditions.

The importance of training

Deploying a large blanket is not as simple as throwing it over a fire. EV and equipment blankets can be heavy, require several people and place those people close to heat, smoke and potentially explosive gases.

If an organization’s emergency plan permits employees to deploy a blanket, those employees need practical training covering:

• Lithium-ion battery hazards and thermal runaway
• The specific equipment and battery systems present onsite
• Early warning signs
• Conditions under which deployment is permitted
• Conditions requiring immediate evacuation
• Team-based deployment techniques
• Safe approach routes and exclusion zones
• Emergency communication and fire department notification
• Thermal and atmospheric monitoring
• Post-incident isolation and reignition precautions

Hands-on drills should take place under controlled conditions and follow the blanket manufacturer’s instructions. Employees should never practise using an actual damaged or overheating battery.

PPE requirements

PPE requirements must reflect the size and condition of the battery, the equipment involved and the employee’s assigned emergency response role.

For limited, pre-incident handling and deployment training, PPE may include:

• Flame-resistant clothing
• Safety glasses, goggles or a face shield
• Heat-resistant gloves
• CSA-approved safety footwear
• A safety helmet or hard hat where required
• High-visibility clothing around vehicles and traffic

This equipment provides limited protection. It is not equivalent to structural firefighting PPE and does not protect an employee from every thermal, chemical, respiratory or explosion hazard.

Active EV or large-battery fires should be managed by trained emergency responders using appropriate structural firefighting PPE and self-contained breathing apparatus.

A blanket is only one part of the response plan

Organizations that store, charge, maintain or operate lithium-ion battery-powered equipment need a broader risk-management program.

That program may include:

• An inventory of battery-powered vehicles and equipment
• Manufacturer-approved charging and storage practices
• Inspection and maintenance procedures
• Controls for damaged, defective or recalled batteries
• Early detection and alarm systems
• Written emergency procedures
• Defined employee and responder roles
• Clear evacuation and exclusion-zone criteria
• Appropriate containment and suppression equipment
• Coordination with the local fire department
• Thermal and atmospheric monitoring
• Post-incident storage, transport and disposal procedures

Emergency planning should also address damaged batteries that have not caught fire. A dropped, crushed, flooded, overheated or visibly swollen battery may remain hazardous even when there is no smoke or flame.

Frequently Asked Questions