Fire Solutions · Specialty

Lithium-ion battery & energy storage fire protection

Lithium-ion batteries fail differently from other fires — thermal runaway cascades between cells, off-gas releases minutes before flame, and standard fire suppression fails to stop re-ignition. CAINtech delivers the Siemens FDA241 + Sinorix NXN combination, a VdS-approved early-detection and nitrogen-suppression solution proven across hundreds of tests on batteries from eight major manufacturers.

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Resources from Siemens

Download the lithium-ion fire protection white paper

Siemens’ technical white paper covers UL 9540A test results, thermal runaway propagation behaviour across cylindrical / prismatic / pouch cell formats, and how the FDA241 + Sinorix NXN combination performs against each. Required reading if you’re specifying fire protection for a BESS, EV parking structure, or data-centre UPS room.

Download brochure (PDF) ↓
2023 updated white paper →

Siemens Sinorix NXN N2 nitrogen fire suppression system

Sinorix NXN N2

Nitrogen suppression validated across every Li-ion cell chemistry

Sinorix NXN uses nitrogen — not a chemical agent — to flood the protected space and starve the fire of oxygen. No residue, environmentally inert, no equipment damage on discharge. Siemens’ published test program demonstrates Sinorix NXN N2 stops the cascading effect of thermal runaway across all three major battery cell formats.

  • Cylindrical cells (e.g. 18650 / 21700 format): stops cell-to-cell propagation.
  • Prismatic cells: stops cell-to-cell propagation.
  • Pouch cells: stops module-to-module propagation.
  • UL and ULC approved — Sinorix NXN N2 carries North American listings, alongside VdS approval no. S 619002 for the combined FDA241 + Sinorix NXN system.

“Test results have shown that the Sinorix NXN N2 product is effective at stopping the cascading effect of thermal runaway for all battery types.” — Siemens 2023 lithium-ion white paper

Lithium-ion battery energy storage systems (BESS), EV charging garages, data-centre UPS rooms, and battery manufacturing all carry a unique fire risk that standard fire protection was not designed for. As a Siemens Solution Partner, CAINtech installs the FDA241 aspirating off-gas detection plus Sinorix NXN nitrogen suppression — the combination Siemens designed specifically for lithium-ion hazards and which holds VdS approval no. S 619002.

5×

Faster detection vs. competitive

NFPA 855

Energy storage standard

VdS

Approved (no. S 619002)

32 min

Lead time before thermal runaway

Detection — FDA241

—Aspirating smoke detector designed for lithium-ion off-gas particle detection
—Patented dual-wavelength optical detection (blue + infrared light)
—5 times faster detection of pending thermal runaway vs. competitive technology
—Detects smoldering at 145°C — 28 min before off-gas venting, 32 min before thermal runaway
—Three operating modes: Ultra-sense, Auto-discrimination, Robust
—Built-in dust discrimination + 4-20 mA output for real-time monitoring

Suppression — Sinorix NXN

—Pre-engineered nitrogen suppression system — no hydraulic calculations needed
—High-pressure cylinders (4,351 PSI) for compact footprint in BESS enclosures
—30+ min hold time in basic-integrity rooms; hours in high-integrity rooms
—Nitrogen is 78% of the atmosphere — clean, eco-friendly, no decomposition agents
—No hydrofluorocarbon byproducts (unlike Novec 1230 / FM-200)
—Proven across hundreds of tests on cells from 8 major manufacturers

Lithium-ion thermal runaway is a different fire

Lithium-ion battery cells contain a high-energy electrochemical system with a flammable electrolyte and an internal oxidizer. When a cell is abused — mechanically, electrically, or by overheating — the result is not a simple fire but an exothermic chemical reaction called thermal runaway:

  • Cascade between cells. Heat from one failing cell transfers to its neighbours, causing each to fail in turn. A 100-cell battery can fully ignite in minutes once the first cell goes.
  • Off-gas releases before visible flame. A failing cell releases a vapour of electrolyte particles and combustion gases (hydrogen, methane, ethane, ethylene, CO, CO₂) before the fire is visible. By the time smoke is detected, the situation has already escalated.
  • Self-feeding reaction. The cell contains its own oxidizer, so removing oxygen (the way clean-agent suppression works) does not stop the reaction inside the cell. The flame stops; the chemistry does not.
  • Re-ignition risk. Cells can re-ignite hours or even days after a fire is “out,” because residual chemistry continues.

FDA241 detects smoldering at 145°C — 28 minutes before off-gas venting and 32 minutes before thermal runaway. This is the ideal precondition for triggering the e-stop, explosion prevention, and fire suppression.

Siemens, Li-ion Early Detection and Suppression Sales Presentation (2025)

Cell types and their failure profiles

Cell typeRisk profileSinorix NXN test result
CylindricLowest fire risk — least shared surface area between cells; the most-tested format in our certification program (8 manufacturers, hundreds of tests).Cell-to-cell thermal runaway propagation stopped every time.
PrismaticHigher risk than cylindric — more shared surface and tighter cell packing.Cell-to-cell thermal runaway propagation stopped every time in nitrogen-inert environment.
PouchHighest risk — high cell density with minimal physical separation. Cell-to-cell propagation is difficult to stop.Module-to-module propagation stopped every time. Cell-to-cell within a single module cannot reliably be stopped for pouch cells.
Siemens BESS container cutaway showing battery racks, Sinorix NXN cylinder, FDA241 detector, and Cerberus PRO panel

The Surprise, Arizona BESS explosion (2019)

On April 19, 2019, a battery energy storage facility in Surprise, Arizona experienced a thermal runaway event that cascaded across battery racks and led to a deflagration explosion when the container was opened. Four firefighters were seriously injured. One of them was thrown 75 feet by the blast.

The facility was equipped with what the industry then considered best-in-class fire protection:

  • A Vesda aspirating smoke detector
  • A Novec 1230 clean-agent suppression system
  • An e-stop procedure

All three operated as designed. The problem was the technology, not the implementation:

  • The Vesda detector triggered only 18 seconds before the temperature peak — not nearly enough lead time to halt thermal runaway
  • The Novec 1230 agent discharged 12 seconds AFTER the temperature had already peaked
  • Thermal runaway continued to cascade from battery to battery even after the suppression system had emptied its agent
  • Flammable off-gases accumulated unchecked until the building was opened by responders — producing the deflagration

When simulating a total flooding system approach, Novec 1230 did not deliver sufficient cooling to prevent propagation of thermal runaway or to prevent thermal exposure to combustible construction materials.

UL 9540A Installation Level Research Tests — Safety Considerations for Outdoor Containerized Li-Ion ESS (April 2021)

The Arizona incident drove the writing of NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems) and the wider adoption of lithium-ion-specific detection and suppression. The FDA241 + Sinorix NXN combination CAINtech installs is the Siemens response to exactly this failure mode.

Why standard fire protection misses lithium-ion fires

Novec 1230 and other clean agents

Clean-agent suppression cools fires by decomposing on hot surfaces. With lithium-ion fires, the problem is that battery surfaces stay very hot for a very long time — long enough that the clean agent continuously decomposes, producing toxic hydrofluorocarbons. Eventually the agent concentration drops below effective levels (and Novec 1230 is heavier than air, so it migrates down and away from the rack tops). When oxygen re-enters the room — usually when first responders open the door — the residual heat plus accumulated explosive gases produces an explosion.

Water sprinklers

Water sprinkler systems were specifically tested by UL against lithium-ion thermal runaway. The UL verdict: “Limited effectiveness to prevent cascading thermal runaway.” Water can help cool an established fire and is often used as a tertiary protection, but it cannot prevent the cascade between cells once it has begun.

Why nitrogen is the right answer

Sinorix NXN floods the protected space with nitrogen, dropping ambient oxygen below the combustion threshold before thermal runaway can propagate. In a nitrogen-rich environment, a cell undergoing thermal runaway experiences a contained “torch effect” — the cell burns out its own internal combustibles in a controlled setting without spreading to other cells or modules. Nitrogen does not decompose, does not produce toxic byproducts, does not damage assets, and requires no cleanup. After discharge the room can be safely purged after a holding period.

Where lithium-ion fire protection applies

CAINtech installs the FDA241 + Sinorix NXN solution in three application classes:

BESS facilities

Battery energy storage at solar and wind generation sites; commercial-scale grid stabilization; load-balancing storage.

UPS rooms

Lithium-ion UPS in data centres, telecommunications facilities, hospitals, clean rooms, and other facilities where continuity is critical.

Demand management

Industrial plants, distribution centres, transportation facilities, metro stations, and battery manufacturing/storage warehouses.

Siemens UPS room cutaway showing server racks, Sinorix nitrogen suppression cylinder, FDA241 aspirating detector, and Cerberus PRO control panel

Inside a protected UPS room

For data-centre UPS rooms, telecommunications facilities, and clean rooms, the protected envelope is a sealed room rather than a containerized BESS unit. The Siemens design uses FDA241 aspirating detectors mounted at strategic sampling points, Sinorix NXN cylinders sized to the room volume, and Cerberus PRO panel integration that interfaces with the building’s main fire alarm system. The room receives an e-stop signal at very early off-gas detection — before the cells have moved into thermal runaway.

Why CAINtech

The Siemens Solution Partner for lithium-ion in Ontario

CAINtech is a Siemens Solution Partner with direct access to the FDA241 + Sinorix NXN combination — the lithium-ion solution Siemens designed and tested for this specific hazard class.
The combination is VdS approved (no. S 619002) and meets NFPA 855 requirements through the NFPA 72 §1.5 equivalency provision.
One accountable team across detection, suppression, panel integration, and ongoing inspection — not a separate Siemens contractor and a separate fire-protection contractor coordinating across an unfamiliar interface.

Frequently asked questions

What is thermal runaway and why is it dangerous?+
Thermal runaway is a self-propagating chemical reaction inside a lithium-ion cell. Once one cell overheats — from internal short circuit, external heat, mechanical damage, or overcharge — the heat transfers to adjacent cells, each fails in turn, and the cascade is very difficult to stop. The reaction releases its own oxidizer, so removing oxygen does not extinguish it. Off-gases (hydrogen, methane, ethane, ethylene, CO) accumulate and can explode if oxygen is reintroduced. In a 2019 Surprise, Arizona BESS explosion, this exact sequence injured four firefighters.
Why don’t standard fire protection systems work for lithium-ion?+
Standard clean agents (Novec 1230, FM-200) and water sprinklers were designed for conventional fires. Clean agents cool by decomposing on hot surfaces — with lithium-ion, the battery surfaces stay too hot for too long, the agent decomposes into toxic hydrofluorocarbons, and concentration drops below effective levels. Water sprinklers were tested by UL and the verdict was “limited effectiveness to prevent cascading thermal runaway.” Both can help with an established fire but neither stops the cascade between cells once it has started. Nitrogen-based inertion is the only suppression technology Siemens has validated as stopping cell-to-cell propagation.
What is NFPA 855 and does it apply to my building?+
NFPA 855 (Standard for the Installation of Stationary Energy Storage Systems) is the U.S./North-American standard that governs the installation, fire protection, and emergency response for stationary battery energy storage systems. It applies to BESS facilities, large lithium-ion UPS systems, and certain battery storage rooms. Adoption into Canadian provincial codes is in progress — consult your AHJ for the current requirements applicable to your specific facility. The FDA241 + Sinorix NXN combination meets NFPA 855 requirements through the NFPA 72 §1.5 equivalency allowance (VdS approval no. S 619002).
Does my BESS / EV parking garage / battery storage room need this protection?+
Three signals say yes: (1) your insurance carrier asks about NFPA 855 compliance or lithium-ion-specific fire protection, (2) your AHJ requires it, (3) the building has significant lithium-ion presence (BESS, large UPS, EV charging stations with onsite battery storage, battery manufacturing/storage). CAINtech does a site walk and review before quoting — the recommendation depends on the specific battery chemistry, cell type, total energy on site, and applicable jurisdiction.
What is VdS approval and how does it map to NFPA 855?+
VdS is a German fire-protection certification body that performs deep technical validation of fire-detection and suppression systems. The FDA241 + Sinorix NXN combination holds VdS approval no. S 619002 specifically for lithium-ion battery off-gas detection plus thermal-runaway suppression. NFPA 72 (the U.S. fire alarm code) Section 1.5 includes an “equivalency” provision that allows products meeting equivalent international approvals (including VdS) to satisfy NFPA detection requirements. This is how the Siemens combination meets NFPA 855 requirements in North America.
How is FDA241 different from Vesda or other aspirating smoke detection?+
Both FDA241 and Vesda are aspirating smoke detectors, but FDA241 uses a patented dual-wavelength optical detection chamber specifically designed to identify lithium-ion electrolyte off-gas particles. Siemens testing showed FDA241 detecting smoldering at 145°C — 28 minutes before off-gas venting and 32 minutes before thermal runaway. That is up to 5 times faster than the alternative detection technologies tested. In the Surprise Arizona incident, the installed Vesda detected the event only 18 seconds before temperature peak.
What happens after Sinorix NXN discharges?+
Once Sinorix NXN releases its nitrogen into the protected space, the room atmosphere drops below the oxygen combustion threshold (under 11.3%). The cell undergoing thermal runaway experiences a “torch effect” within its own envelope and burns out its internal combustibles without propagating to adjacent cells. After the overpressure flaps stop moving, the recommended procedure is to wait at least 30 minutes (often longer for room integrity) before venting and exhausting. The FDA241 continues to monitor; gas sensors (if installed) report; ambient and cell temperatures are tracked. Firefighters enter only after the room has been safely purged of nitrogen.
Does it work for pouch cells / prismatic / cylindric cells?+
Yes, with cell-type-specific outcomes. Cylindric cells (the most common large-format format): Sinorix NXN stopped cell-to-cell propagation every time in Siemens testing across 8 manufacturers and hundreds of tests. Prismatic cells: same — cell-to-cell propagation stopped every time in nitrogen-inert environments. Pouch cells (highest fire safety risk due to high density and minimal separation): cell-to-cell propagation cannot reliably be stopped, but module-to-module propagation has been stopped every time. For pouch-cell applications, the protection strategy focuses on containing each module to limit the size of the event.
How does the system integrate with the building’s main fire alarm panel?+
The FDA241 + Sinorix NXN system reports to a Cerberus PRO fire alarm panel as a supervised zone. Detection alarms appear on the main panel with location detail; suppression discharge is monitored as a supervisory event; supervisory faults (loss of nitrogen pressure, etc.) report immediately. Building staff and CAINtech see events on the panel display and, where Building X cloud monitoring is enabled, on remote dashboards (see Building X for portfolio-wide visibility). The system can also be configured to trigger an e-stop to the battery management system at very early off-gas detection, breaking the electrical supply to the affected cells.
What does the engineering and quote process look like?+
For a BESS facility, large UPS room, or battery manufacturing space, CAINtech does a site walk to confirm the protected envelope dimensions, battery chemistry, cell type, and integration with the existing fire alarm system. We then size the FDA241 sampling pipe network, the Sinorix NXN cylinder volume, and the panel integration. The quote covers design, equipment supply (FDA241 + Sinorix NXN are non-substitutable Siemens products under the VdS approval), installation, commissioning, CAN/ULC-S537:2019 verification where applicable, AHJ submission, and a first-year inspection cycle. We can phase the install around facility uptime needs.

Lithium-ion fire protection assessment

Send us the building scope — BESS, EV parking, UPS room, or battery storage facility. We do a site walk and follow up with a sized solution and quote. Mon to Fri, 7:00 AM to 3:30 PM.

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