FM Global DS 7-112: Lithium-Ion Battery Manufacturing and Storage Fire Protection

Lithium-ion cell manufacturing and storage combine two different hazards: ignitable liquids, ovens and solvent recovery in production, and stored chemical energy with thermal runaway in the finished cell. FM Global DS 7-112 Lithium-Ion Battery Manufacturing and Storage (October 2024, interim revision April 2025) covers both. This article summarises the clauses that matter most in practice.

Scope (§1.0)

• Covered: manufacturing, assembly, testing, finishing (formation, aging) and storage of liquid-electrolyte lithium-ion cells, modules and batteries, and the assembly and storage of end-use products containing them.
• Not covered: energy storage systems (DS 5-33), battery backup units (DS 5-32), products in use while being charged or discharged including electric vehicles, cell recycling, second-use facilities and lithium-metal batteries.
• Some chemistries are less prone to thermal runaway, but all contain an ignitable liquid electrolyte, so the data sheet does not differentiate protection by cell chemistry (§1.1, §3.2).

Hazards (§1.1)

• Thermal runaway (§1.1.1): internal cell defects, mechanical or impact damage, external heating, overvoltage charging or battery management system (BMS) failure can cause an internal short. The cell builds up heat and flammable gas; hot vented gas directed at adjacent cells can propagate runaway from cell to cell.
• Abuse (§1.1.2): electrical (improper charging or discharging), thermal (high temperature) and mechanical (impact).
• Fire (§1.1.3): once combustion starts in a cell enclosed in a module or pack, it will likely spread until all charged cells are consumed; to date no testing shows that active fire protection can stop this when the cells are enclosed. Sprinklers cool the structure, combustibles and adjacent modules to limit spread.
• Reignition (§1.1.4): a single cell cannot reignite; once in runaway it burns until consumed. Modules and packs, however, can reignite through the delayed ignition of some cells. Batteries involved in a fire must be adequately cooled and moved to a safe location.
• Explosion (§1.1.5): unignited hot vent gases can accumulate in a closed module, equipment, cabinet or room and deflagrate.
• Operating window (Appendix C.3): cells generally operate between 0 °C and 100 °C and 2–4 V; above 100 °C the SEI layer breaks down and above 200 °C the cathode active material decomposes. Electrolyte breakdown releases flammable hydrocarbon gases and cathode breakdown releases oxygen (Appendix C.3.5).

Construction and Separation (§2.2)

• Noncombustible or FM Approved Class 1 materials for construction and equipment enclosures (§2.2.1).
• At least one-hour rated, noncombustible fire walls between manufacturing, formation/aging and warehouse storage (§2.2.2), with normally closed or automatic-closing FM Approved fire doors (§2.2.3).
• Areas with large numbers of finished cells, and clean rooms, are subdivided with noncombustible walls to limit nonthermal (smoke, corrosion) damage (§2.2.2.1).
• Quality control testing involving charging and discharging takes place inside ventilated hoods or enclosures (§2.2.6).

Ventilation and Gas Detection (§2.3)

• A dedicated, nonrecirculating mechanical exhaust for enclosures and hoods where charging takes place, with make-up air from fresh-air areas only, at a minimum of 1 cfm/ft² (0.3 m³/min/m²) (§2.3.2.1).
• An emergency ventilation rate of 150% of the standard rate, activated on gas detection or at 25% of the lower explosive limit for hydrocarbon gases (§2.3.2.1.4).
• FM Approved off-gas detection inside those hoods and enclosures, alarming remotely if testing runs during unoccupied hours (§2.3.1.2).
• In manufacturing areas the air-conditioning supply and return fans shut down when the fire protection system operates (§2.3.2.2.1).
• Electrical equipment rated for hazardous (classified) locations, plus grounding and bonding, wherever flammable vapours or gases may be present (§2.9).

Protecting Manufacturing Areas (§2.4.1)

• Electrode, cell, module and battery manufacturing and assembly areas: automatic sprinklers with a minimum HC-3 design per DS 3-26 (§2.4.1.1.1). FM Approved HC-3 water mist may be used if all concealed spaces are adequately protected (§2.4.1.1.3).
• Additional sprinklers or water mist inside enclosed equipment of combustible construction (ovens, hoods, test enclosures) and inside enclosures where high-hazard processes such as electrolyte filling or cell charging/discharging take place (§2.4.1.2.1).
• Other process hazards follow the data sheets in Table 2.1.3: ovens and dryers DS 6-9, ignitable liquid operations DS 7-32, ignitable liquid storage in portable containers DS 7-29, solvent recovery DS 7-2, combustible dusts DS 7-76, industrial exhaust DS 7-78, heat transfer fluids DS 7-99 (§2.5).
• NMP above 85% by volume in water is treated as a Group 3 water-miscible liquid; at 85% or below, as Group 5 (§2.1.4).

Formation and Aging Areas (§2.4.2)

Formation and aging areas, where cells are charged and discharged for the first time, are expected to see more thermal runaway events than normal. Rack arrangements use in-rack sprinklers with horizontal and vertical barriers: a maximum of 1.8 m between levels, at least 227 L/min from each of the most remote 6 sprinklers (one barrier level) or 8 sprinklers (two or more levels), a 1,900 L/min hose allowance and a two-hour water supply. The details are in the formation area article.

Storage (§2.4.3–§2.4.7)

• Incidental storage (§2.4.3.1): metal or cardboard boxes, no more than 20 m² per area, no more than 1.8 m high, at least 3.0 m aisles between areas and a state of charge (SOC) of 60% or less.
• In plastic containers (§2.4.3.2): within the same limits, protected as low-piled uncartoned unexpanded plastic (UUP) per Table 2.4.3.2. Incidental storage needs a 1,900 L/min hose allowance and a one-hour water supply (§2.4.3.4–§2.4.3.5).
• Batteries in finished products (§2.4.4): at 60% SOC or less, the product is protected under DS 8-9 using its own commodity classification, excluding the battery hazard; above 60% SOC, both ceiling and in-rack sprinklers are needed.
• New or refurbished cells, modules and batteries (§2.4.5): at 60% SOC or less, with a ceiling up to 13.5 m (45 ft) and storage up to 4.5 m (15 ft), they are protected as CUP, CEP, UUP or UEP (depending on packaging) using the DS 8-9 tables and quick-response sprinklers only (Tables 2.4.5.1-1 and 2.4.5.1-2). Beyond these limits, racks need in-rack sprinklers with horizontal barriers, at a maximum of 3.7 m between levels (§2.4.5.5–§2.4.5.6).
• At least 3.0 m between lithium-ion storage and other combustibles; in solid-piled and palletized storage, contiguous blocks no wider than 4.6 m with 3.0 m aisles (§2.4.5.3–§2.4.5.4).
• Designs with in-rack sprinklers need a 1,900 L/min hose allowance and at least a one-hour water supply; the in-rack system is not hydraulically balanced with the ceiling system (§2.4.5.8).
• Returned, defective or damaged cells (§2.4.6): kept outdoors or in a cut-off room. Outdoors: two pallets high, piles no larger than 83.6 m², 3.0 m between piles. Indoors: one pallet high, with 12 mm/min (0.3 gpm/ft²) over the room footprint for floor or palletized storage. 1,900 L/min hose allowance, two hours.
• ASRS (§2.4.7): finished products at 30% SOC or less are protected per DS 8-34 with a wet system only; between 30% and 60% they must be in FM Approved non-flame-propagating or steel containers, in horizontal-loading ASRS only, with ceiling and in-rack sprinklers. Products above 60% SOC are not stored in ASRS.

Operations and Emergency Planning (§2.3.1, §2.7, §2.8)

• Documented procedures for handling damaged or off-specification cells and for responding to thermal runaway in formation, aging and finished-cell storage areas (§2.3.1.3–§2.3.1.4).
• A pre-incident and emergency response plan developed with the local fire department, covering access routes, water for long-duration fires, smoke ventilation, an outdoor location for damaged cells and a final extinguishment plan for prolonged burning (§2.8.1).
• A post-incident recovery plan addressing reignition and the removal and disposal of damaged cells, with a fire watch until all potentially damaged cells have been removed (§2.8.2–§2.8.3).
• Training covering ignitable liquids and the stored-energy hazard of finished cells (§2.7).

Quick Checklist

• One-hour noncombustible fire walls between manufacturing, formation/aging and storage
• Minimum HC-3 (DS 3-26) in manufacturing and assembly areas
• Dedicated exhaust, emergency ventilation and off-gas detection in charging enclosures
• In-rack sprinklers with barriers and a two-hour water supply in formation and aging racks
• Storage mapped to DS 8-9 by SOC, packaging, ceiling and storage height
• Damaged cells outdoors or in a cut-off room
• Thermal runaway response procedure, emergency and post-incident plans

Frequently Asked Questions

Why is a lithium-ion battery fire hard to control?

Under DS 7-112 §1.1.3, once combustion starts in a module or pack it will likely spread until all charged cells are consumed, and to date no testing shows that active fire protection can stop this when the cells are enclosed. Sprinklers are therefore there to limit fire spread to the surrounding structure, equipment and contents (§2.4.1).

Does lithium-ion storage require a specific sprinkler density or ESFR?

DS 7-112 does not give its own density table. At 60% SOC or less, with a ceiling up to 13.5 m and storage up to 4.5 m, the storage is treated as CUP, CEP, UUP or UEP depending on packaging and protected using the DS 8-9 tables with quick-response sprinklers only (§2.4.5.1). Beyond these limits, racks need in-rack sprinklers with horizontal barriers (§2.4.5.5–§2.4.5.6).

Why does the state of charge (SOC) matter so much?

According to DS 7-112 §3.4.3, cells below 30% SOC are very difficult to get into thermal runaway, while charge above 60% is generally intended for immediate use, and the higher the SOC the more reactive a battery is in a fire. That is why the storage rules are tied to 60% and the ASRS rules to 30% and 60%.

Are battery energy storage systems (BESS) covered by DS 7-112?

No. DS 7-112 §1.0 excludes energy storage systems and refers them to DS 5-33; battery backup units fall under DS 5-32.

What should be done with batteries involved in a fire?

DS 7-112 §1.1.4 says they need to be adequately cooled and moved to a safe location. §2.8 calls for a post-incident recovery plan addressing reignition and a fire watch until all potentially damaged cells have been removed; the data sheet does not specify a fixed holding time.

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