SHENZHEN, China, July 24, 2025 /PRNewswire/ — CLOU, a BNEF Tier 1 energy storage system provider, has officially released its White Paper on Active Ventilation & Explosion-Proof System, offering an in-depth look into the company’s next-generation fire safety architecture for energy storage systems. The release follows the successful completion of a 59-hour and 10-minute Large-Scale Fire Test of its 5MWh Aqua C2.5 liquid-cooled BESS in April.
The large-scale fire test, fully witnessed and documented by CSA Group, simulated an extreme thermal runaway scenario. Four fully loaded Aqua C2.5 containers (A/B/C/D), forming a 20MWh system, were installed back-to-back and side-by-side to replicate actual high-density station layouts. Container A was intentionally ignited and sustained combustion for nearly 60 hours, with internal temperatures exceeding 1300°C. Remarkably, no fire suppression system was activated, allowing the test to validate the fire endurance of a single container and the safety performance of CLOU’s Active Ventilation & Explosion-Proof System. No thermal propagation occurred between the adjacent units, underscoring the system’s reliability in dense deployments.
In recent years, the ESS industry has faced growing concerns over safety, with hundreds of fire and explosion incidents reported globally. As the region with the world’s most comprehensive energy storage safety standards, North America has responded by implementing a rigorous regulatory framework that span full lifecycle risk management—from cell-level to station-wide protection systems. Core standards include NFPA 855, NPFA 68, NFPA 69, UL 9540 and CSA/ANSI C800.
Guided by these frameworks, CLOU has developed a comprehensive multi-layered fire protection system to safeguard customer assets throughout their lifecycle. This safety system—detailed in the white paper— is based on lean engineering principles and includes:
Early Warning & Detection of Thermal Runaway – BMS monitors voltage/temperature in real-time, triggering alarms and disconnecting circuits to prevent propagation. Sensors activate active ventilation explosion-proof systems to suppress explosion risks before fires occur.
Dual-Layer Fire Suppression – CLOU enhances traditional total flooding gaseous fire suppression systems with a water spray addition: it rapidly cools to prevent reignition and syncs with the ventilation system to reduce flammable gas concentration.
Explosion Protection: Active-Passive Defense – Preemptive Control: Ventilation systems maintain flammable gas concentrations below 25% LEL—preventing explosive conditions at source per NFPA 69. Engineered Venting: Directional pressure-release structures localize blast impacts, preventing chain reactions.
Active Ventilation & Explosion-Proof Design – integrates five natural exhaust louvers and two intakes to maintain flammable gases below 25% LEL even during single-intake failures (per NFPA 69 verification). The louvers simultaneously serve as pressure-relief vents during explosions, directing flames vertically upward to prevent cross-container propagation, while ensuring continuous ventilation through thermal pressure differences in power outages.
CLOU’s latest innovations reflect its ongoing commitment to advancing industry safety benchmarks. The white paper is now available for download and serves as a practical reference for developers, EPCs, regulators, and asset owners seeking enhanced safety and long-term system reliability.
Download the white paper here: https://www.clouess.com/news/317.html
Video – https://mma.prnewswire.com/media/2737607/CLOU_Aqua_C2_5_59_Hour_Large_Scale_Fire_Test.mp4
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