EV Fire Blankets and the Risk of Battery Gas Explosions

DVM International | Technical Insights

Understanding thermal runaway, flammable gas accumulation, explosion hazards and the limitations of gas-venting blanket designs.

EV fire limitation blankets are designed to restrict flame spread and reduce heat exposure to surrounding vehicles, buildings and equipment.

By covering a burning vehicle, a blanket can restrict the oxygen supply and suppress visible flames. However, when an electric vehicle's lithium-ion traction battery is involved, an additional hazard must be considered: the release and accumulation of flammable battery gases.

A fire that appears to be under control may still contain an active battery undergoing thermal runaway.

Recent research has demonstrated that these gases can accumulate beneath a fire blanket and, under certain conditions, create a serious explosion hazard.

Understanding this phenomenon is essential for firefighters, emergency responders, vehicle recovery operators and professional buyers.

For information about our professional EV fire limitation blanket, see the DVM-FLB-6×8 product page.

1. What Happens During Battery Thermal Runaway?

Thermal runaway is a self-sustaining process in which a lithium-ion battery cell releases heat faster than it can dissipate it.

Depending on battery chemistry and conditions, the process may release flammable gases, including hydrogen, carbon monoxide and various hydrocarbons.

Several important characteristics distinguish battery thermal runaway from conventional vehicle fires:

• Battery cells may continue producing heat and gases even when external flames have disappeared.
• Thermal runaway can propagate from one cell to neighbouring cells.
• Gas release may occur suddenly and with considerable force.
• Oxygen from the surrounding atmosphere is not required for every stage of the internal battery decomposition process.

Consequently, restricting the external oxygen supply does not necessarily stop thermal runaway.

This is a fundamental limitation of any fire limitation blanket used on an EV with an actively failing battery.

2. How Can Flammable Gases Accumulate Beneath a Fire Blanket?

When a blanket covers a burning vehicle, it restricts the exchange of air between the space beneath the blanket and the surrounding environment.

This can help reduce visible flaming and heat radiation.

However, the battery may continue releasing flammable gases.

If these gases cannot disperse sufficiently, their concentration may increase in the space beneath the blanket.

An explosive event becomes possible when a suitable mixture of fuel and oxygen encounters an effective ignition source.

The precise hazard depends on several factors, including gas composition, temperature, ventilation, battery condition and the geometry of the enclosed space.

3. What Has Independent Research Revealed?

In May 2025, the Fire Safety Research Institute (FSRI) and the Fire Protection Research Foundation (FPRF) issued a joint warning following experiments involving electric vehicle fire blankets.

Their observations showed that fire blankets could eliminate visible flames while thermal runaway continued inside the traction battery.

The continuing release of flammable gases created conditions in which explosive ignition was possible.

Subsequent FSRI research, published in August 2026, provided further evidence of the hazards associated with accumulated gases, blanket movement and the reintroduction of oxygen.

These findings are particularly important because they demonstrate that visible flame suppression should not be confused with the elimination of the underlying battery hazard.

4. What Have European Researchers Found?

Research outside the United States provides additional insight.

The Danish Institute of Fire and Security Technology (DBI), through its BESAFE research, investigated the fire and explosion behaviour of lithium-ion batteries.

In controlled module-level experiments, explosions occurred in three of four relevant tests, demonstrating the potential severity of accumulated battery gases.

Although these experiments did not directly compare EV fire blankets, they provide important evidence about the hazards associated with battery gas release in confined volumes.

European full-scale vehicle fire research has also investigated fire blankets and other suppression methods.

For example, experiments reported in Fire Safety Journal examined vehicle fires in an open-sided enclosure. A fire blanket produced an initial temperature reduction, followed by a subsequent increase. No deflagration was observed during the blanket experiment, illustrating that explosion outcomes depend on the particular conditions.

The European research therefore supports a careful conclusion: gas accumulation is a credible hazard, but the occurrence and severity of an explosion cannot be predicted solely from the presence of a fire blanket.

5. Can Gas-Venting Openings Reduce the Explosion Risk?

Some EV fire limitation blankets are now offered with specially designed gas-release openings or ventilation features.

These designs are intended to provide an escape path for gases released beneath the blanket, potentially reducing their accumulation.

The concept is technically understandable. However, several important questions remain:

• Can the openings discharge flammable gases quickly enough during rapid battery venting?
• Could they allow additional oxygen to reach the fire?
• Could flames or burning gases emerge through the openings?
• How does the design perform under different wind and ventilation conditions?
• Does the modification compromise the blanket's ability to limit flame spread and heat radiation?

Based on the independent research reviewed for this article, we have not identified conclusive comparative full-scale testing demonstrating that commercially available gas-venting EV blankets consistently reduce explosion risk compared with conventional blanket designs.

This does not mean that gas-venting systems are ineffective.

It means that their claimed safety benefits require independent verification under representative conditions.

Until such evidence is available, gas-venting features should be regarded as a design approach whose effectiveness remains to be established.

6. Why Enclosed Spaces Present Additional Risks

The environment surrounding an EV fire can significantly influence the consequences of gas release.

In open-air conditions, escaping gases may disperse into the atmosphere, although local accumulations and ignition hazards can still occur.

In enclosed or poorly ventilated environments, gases escaping from beneath a blanket may accumulate elsewhere.

Examples include parking garages, vehicle workshops, underground storage facilities and enclosed transport decks.

Guidance published by the UK government for vehicle recovery operators explicitly recognises the possibility of vapour-cloud explosions associated with gases escaping from beneath fire blankets, particularly in enclosed spaces.

A blanket should therefore never be considered an independent solution to the hazards of an EV battery fire in an enclosed environment.

7. Why Moving or Removing a Blanket Can Be Dangerous

A particularly dangerous situation may arise when a blanket is lifted, repositioned or removed while flammable gases remain present.

Fresh air entering an oxygen-depleted space can create conditions suitable for rapid ignition.

If an ignition source remains, the resulting combustion may be sudden and violent.

FSRI's full-scale experiments demonstrated hazards associated with disturbing the blanket and introducing air or firefighting equipment beneath it.

For this reason, the absence of visible flames must never be interpreted as confirmation that the vehicle is safe.

Blanket removal, continued firefighting, battery cooling and vehicle recovery require appropriate professional assessment and established emergency-response procedures.

Does DIN 91489-1 Specify How Long a Blanket Must Remain in Place?

Unlike the operating instructions commonly associated with conventional fire blankets under EN 1869, DIN 91489-1:2026-11 does not prescribe a fixed minimum period for leaving an EV fire limitation blanket in place after deployment.

Instead, Section 12 requires manufacturers to provide instructions concerning monitoring, because delayed re-ignition may occur.

The standard also requires manufacturers to inform users that fire limitation blankets do not provide additional protection against explosive pressure and that they restrict, but do not completely prevent, the spread of smoke gases.

This distinction is important. Lithium-ion battery thermal runaway can continue even after visible flames have disappeared. Consequently, removing a blanket after an arbitrary period could expose emergency responders to renewed flames or accumulated flammable gases.

The decision to remove a blanket should therefore be based on professional assessment, continued monitoring and appropriate emergency-response procedures, rather than on a predetermined waiting time.

8. What Can EV Fire Limitation Blankets Still Contribute?

The explosion hazard does not mean that every application of an EV fire limitation blanket is without value.

Depending on the circumstances, a suitable blanket may help:

• Limit the spread of flames to adjacent vehicles or equipment.
• Reduce heat radiation towards nearby exposures.
• Restrict the involvement of combustible vehicle components.
• Provide temporary fire limitation while emergency responders assess the incident.

However, these potential benefits must be evaluated alongside the hazards of battery gas production, restricted ventilation and possible re-ignition.

An EV fire limitation blanket is a fire-limitation tool, not a guaranteed battery extinguishing system or explosion-prevention device.

Professional buyers should therefore consider the intended application, operational procedures, training and independently documented performance rather than relying on broad marketing claims.

Our DVM-FLB-6×8 EV Fire Limitation Blanket is being developed with this distinction between fire limitation and battery extinguishing firmly in mind.

9. DVM International's Approach

DVM International believes that the benefits and limitations of EV fire limitation blankets should be communicated transparently.

Our DVM-FLB-6×8 is being developed for professional fire limitation applications, with independent testing intended to support its technical performance claims.

We distinguish between limiting fire spread, withstanding thermal exposure and controlling the hazards generated by battery thermal runaway.

These are related, but fundamentally different, safety objectives.

Independent testing and the applicable requirements of DIN 91489-1:2026-11 provide an important framework for evaluating the product's specified performance.

However, conformity with a fire limitation blanket standard must not be interpreted as proof that all possible battery gas explosion scenarios have been eliminated.

Conclusion

EV fire limitation blankets can play a role in managing the consequences of vehicle fires, but their use requires a clear understanding of lithium-ion battery behaviour.

Independent research has shown that suppressing visible flames does not necessarily stop thermal runaway or the release of flammable gases.

Gas accumulation beneath a blanket can create an explosion hazard, particularly when oxygen is subsequently introduced or gases accumulate in poorly ventilated surroundings.

Blankets incorporating gas-venting features are commercially available, but convincing independent comparative evidence demonstrating their effectiveness in preventing explosions remains insufficient.

The appropriate approach is therefore neither to dismiss EV fire limitation blankets altogether nor to treat them as universally safe solutions.

Their use should be based on independently verified performance, realistic risk assessment and clearly defined operational limitations.

References and Further Reading

1. Fire Safety Research Institute (FSRI) and Fire Protection Research Foundation (FPRF). Joint safety warning on electric vehicle fire blankets, May 2025.
2. Fire Safety Research Institute (FSRI). Full-scale electric vehicle fire blanket research and operational findings, August 2026.
3. Danish Institute of Fire and Security Technology (DBI). BESAFE research on lithium-ion battery gas explosions.
4. European full-scale vehicle fire research published in Fire Safety Journal, including fire blanket experiments.
5. UK Government. Guidance for vehicle recovery operators concerning electric vehicle battery fires and associated hazards.
6. DIN 91489-1:2026-11. Fire containment blankets – Part 1: Requirements for fire containment blankets for use with electric vehicles.

This article provides a technical overview and does not replace the complete official standard, emergency-response procedures or product-specific safety instructions. Product conformity must be assessed against the applicable requirements and supporting test evidence.