FAQ's for lithium fire safety

[Sifu]

Admittedly, this is way outside my level of expertise, but this FAQ from the NFPA on lithium fire safety is supposed to clear up some confusion, but it confuses me.

I underlined something that caught my eye in the FAQ's, I have pasted the relevant parts below. On one hand it says lithium fires happen because the lithium in the batteries is exposed to water, on the other hand it says fire is adequate as an extinguishing agent because the type of material in a battery isn't the kind that ignites when exposed to water.

What is my misunderstanding?

How do fires from lithium-ion batteries start?

Lithium-ion battery fires happen for a variety of reasons, such as physical damage (e.g., the battery is penetrated or crushed or exposed to water), electrical damage (e.g., overcharging or using charging equipment not designed for the battery), exposure to extreme temperatures, and product defects.

Once the batteries catch fire and water is applied to them, does it make the fire worse because lithium in the presence of water creates combustible hydrogen?

Firefighters should use water to fight a lithium-ion battery fire. Water works just fine as a fire extinguishing medium since the lithium inside of these batteries are a lithium salt electrolyte and not pure lithium metal. Confusion on this topic stems from the fact that pure lithium (like what you see in the table of elements) is highly reactive with water, while lithium salts are non-reactive with water.

 

[Inspector Gadget]

I think the critical issue with Lithium batteries is that far, far too many of them are imported from Asia and a staggering number of them lack any measure of testing - or improper testing. I live off-grid and recently sourced a LiFePO4 battery - only *one* company had the required CSA/ULC approval. The rest were cheaper ....

 

[Sifu]

This event occurred as I pondered the Lithium energy project I have. Admittedly a different situation, but still involved a large amount of the material. They appear to be batteries, from Vietnam, 2,000 tons according to a NYT article. Assuming they are already assembled and packaged. No details for what caused the fire, but it was apparently difficult to handle, at least on board the ship, until the ship was close enough to have land based crews go to work on it.

One of the points that has been made on my project is that the batteries are already assembled, so there is no danger.

A lithium-ion battery fire in a cargo ship's hold is out after several days of burning

The U.S. Coast Guard says a lithium-ion battery fire on a cargo ship is out after days of burning off the coast of Alaska

abcnews.go.com

 

[BN4537]

I'm not going to pretend to be an expert, but I think it has to do with the quantities involved.

(My theory) Water and lithium burn because of a chemical reaction. Like any chemical reaction, the most violent reaction requires a precise ratio of the chemicals to be mixed. Too much of any ingredient will retard the process and the reaction.

As an example, I think we have all seen the vinegar-and-baking-soda chemical reaction. If you have ever experimented with it, say by doubling the vinegar, it really starts to degrade the reaction the further away from the optimum ratio you get.

So, my guess is that a small amount of water is bad and would cause a fire, but the more water you add the more you retard the chemical reaction until ultimately it puts the fire out.