Batteries: Some answers to burning questions

While there are many varieties, the basic two categories of lithium-type batteries are lithium primary – non-rechargeable cells often used in watches and hearing aids – and lithium-ion – rechargeable cells often used in a wide range of consumer electronics and electric vehicles. The technology behind these high-power-to-density batteries provides long-lasting, reliable energy for countless everyday electronic devices, but they can lead to potential catastrophes when they burn, creating fires that are some of the most difficult to suppress.

When lithium-type batteries are packaged together in bulk – especially the lithium-ion variety – and are damaged by jostling, they are sometimes subject to a chain-reaction known as “thermal runaway.” This phenomenon occurs when the internal circuitry is compromised, causing an increase in temperature in one or more cells. The heat can reach a point at which the cell vents hot gases, which can then increase the temperature in adjacent cells and so on, leading to a potential ignition.

Once a fire starts, the small amounts of lithium and metal-oxides inside each cell are extremely reactive to oxygen and can burn at high temperatures, even after all the surrounding oxygen has been consumed. Instead of water, these fires require a suppressing foam, CO2 gas or dry chemical extinguisher to smother the fire and rapidly lower its temperature.

Although it is being phased out for being an ozone-depleting chemical, Halon, a liquefied compressed gas, was for many years the fire-suppression material of choice for these hot, metal-fed fires, and is still often found in extinguishers in the bellies of aircraft. However, according to Jeremy Snow, president of Ventura Aerospace, Halon doesn’t work on lithium primary batteries, because it liberates fluorine gas, which can become an oxidizer that can fuel the fire even more. Lithium ion batteries will also continue to burn in the presence of Halon, he said, “but it won’t make [the fire] worse.”

Back to home page https://aircargoworld.com/to-the-rescue/