How to Achieve Explosion Control in a BESS
Due to the “cascading” element of thermal runaway, the more battery cells that are affected, the more explosive gasses that are generated. Learn how Fike’s decades of experience in explosion protection combined with Fike Blue ensures these gases are mitigated before combustion may occur.
When is Explosion Control Required?
Along with the intense heat generated from each affected battery cell during thermal runaway is a dangerous mixture of offgassing “mixtures of CO, H2, ethylene, methane, benzene, HF, HCl, and HCN...” (NFPA 855, A.9.6.5.6)
That’s why NFPA 855 requires “explosion control” as an essential element to the overall safety of a BESS, and more specifically that flammable gas concentrations must not exceed 25 percent of the Lower Flammability Limit (LFL) where gas may accumulate. A BESS that proves via a UL 9650A test that its LFL is maintained under this threshold is exempt by NFPA 855 from requiring explosion prevention and venting.
However, for those installations that do require explosion control, or even for AHJs (Authorities Having Jurisdiction) who require further protection, some methods that are recommended by both NFPA and Fike to reduce the risk of combustion include:
“Explosion control in the context of an ESS should include a vent because every battery that goes into thermal runaway generates explosive gas in that atmosphere and it has to go somewhere. It may be possible to achieve enough ventilation to stay below 25 percent of the LFL, but in the case of an unpredictable factor such as an electrical failure that may take those systems down, passive explosion venting is still highly recommended in many applications.”
Tom Farrell, Fike Principal Engineer of Test & Validation
How Fike Blue Reduces Offgas from Thermal Runaway
Finally, one other explosion control method exists that is not yet included in NFPA 855 – Fike Blue. Fike Blue flows through the ESS during the early stages of thermal runaway, fills the affected battery module and absorbs the heat to ensure the cascading event is stopped.
Numerous tests at the Fike Innovation and Testing Center have proven that applying Fike Blue normally saves all of the battery cells within the module except for the initial malfunctioning battery and potentially a few of the adjacent cells. Because the spread of thermal runaway is suppressed, the remaining battery cells within the module will be unaffected and therefore will not produce offgas, resulting in a much safer outcome than other scenarios such as letting the module, and potentially the entire ESS, consume itself.
“If you have 1,000 cells inside a battery, and you let all those burn, you generate 1,000 cells worth of toxic gas that is going into occupied spaces and rendering them unoccupiable for some time. If you’re able to suppress it and stop propagating thermal runaway, instead of losing 1,000 cells, you may only lose 50, which means that gas can be dispersed and get to levels which are not quite so toxic. Fike Blue is the only solution that effectively reduces the offgas generated from these hazards.”
Tom Farrell, Fike Principal Engineer of Test & Validation
Why Fike for Explosion Control?
Fike is one of the only organizations in the world capable of protecting people and critical assets from the dangers of explosion and thermal runaway hazards. With decades of experience providing explosion protection consultancy, dust testing, risk assessments, system design, installation and maintenance, and now with the development and validation of Fike Blue, Fike is uniquely capable of creating non-standard protection strategies for a BESS and helping manufacturers reach UL 9540A certification and AHJ requirements.