Spring Meeting 2025 “Virtual” Follow-Up

Tuesday, April 29th, 2025

Norm Barrientos provided this follow-up answer to one of the questions:

In response to the allowable fire suppression systems, I did some further research, and water is currently the recommended approach. It is also recommended to have portable fire extinguishers with High-Flow ABC Dry Chemicals.

Here is some more information on EV-based fire suppression systems:

Water-Based Suppression:
Automatic Sprinkler Systems: Installing automatic sprinklers are the best practice for EV repair facilities. Newer standards like NFPA 13-2022 recommend designing for Ordinary Hazard Group 2 (OH2) density (approximately 0.2 gpm/ft²) for areas housing modern vehicles, which includes EVs.

Water sprinklers are the best fire suppression method for an EV fire within a repair garage and are effective in cooling the battery to stop thermal runaway. Water has a significant cooling capacity for thermal events.

For dedicated battery storage areas, even higher densities based on NFPA 855 or FM Global guidance (e.g., 0.3 gpm/ft²) are recommended. Ensuring an extended water supply duration (potentially 90 minutes or more) is also crucial due to the prolonged nature of EV battery fires.

Manual Application (Fire Department Response):
Fire department intervention for an EV battery fire typically requires the application of very large quantities of water continuously over extended durations to achieve sufficient cooling and mitigate re-ignition. Firefighters may use thermal imaging cameras (TICs) to monitor battery temperature.

Portable Fire Extinguishers:
High-Flow ABC Dry Chemical Extinguishers: The 2021 edition of NFPA 30A requires high-flow portable fire extinguishers in repair garages, specifically mandating at least 10-lb ABC dry chemical extinguishers with a minimum discharge rate of 1 pound per second.

These should be placed with a maximum travel distance of 50 feet (or 100 feet for 20-lb units) from any point in the service area. While effective for small, incipient fires or fires around the battery, standard portable extinguishers are generally ineffective at extinguishing a fully developed lithium-ion battery thermal runaway event due to their lack of sustained cooling capacity.

Specialized Agents(Not Necessarily “Allowable” by Code Yet):
Encapsulating Agents (e.g., F-500 EA®, FCL-X™): These water additives enhance cooling and encapsulate fuel molecules. Testing suggests improved suppression and reignition prevention compared to water alone. However, they are proprietary, cost more, and require further validation and inclusion in standardized guidelines.

Water Mist Systems:
These systems use a fine mist for efficient cooling and potentially reduced water usage. Research suggests they can be effective in controlling thermal runaway, especially with early activation.

Suppression Methods with Limited Effectiveness:
Gaseous Agents (e.g., CO₂, Clean Agents): These suppress flames from burning vapors but have limited cooling capacity and are unlikely to stop thermal runaway or prevent re-ignition.

Dry Chemical Agents (ABC or BC):
These dampen down flames but offer minimal cooling and are ineffective at halting thermal runaway or preventing re-ignition.