Comment by lwhi
9 days ago
Witness A said, “It appears that the fire started when a spark flew during the process of replacing the uninterruptible power supply,” and added, “Firefighters are currently out there putting out the fire. I hope that this does not lead to any disruption to the national intelligence network, including the government’s 24 channel.”[1]
How large is this UPS that a fire can bring down all 96 servers?
This story is really unbelievable.
I’m no expert but traditional lead acid battery UPS are typically at the bottom of the rack due to weight and concern about leakage. Wouldn’t surprise me if li-ion UPS go at the bottom as well. In that case if uncontrolled it seems pretty easy to torch an entire rack.
96 servers isn’t that many, probably less than 10 racks and given the state of the backups it would track that they didn’t spring for halon.
depends on how many batteries were in the facility, if one goes up chances are the rest go too. Can halon systems not put out lithium fires?
Lithium ion batteries provide their own oxidiser, removing oxygen won't put them out (though it will probably help stop the fire from spreading). The only thing that kinda helps is removing the heat (with cold C02 or water, the latter not great for an electrical fire and the former only good for pretty small fires), but that's only a temporary fix usually. Ultimately a lithium battery fire has got to burn itself out.
>Can halon systems not put out lithium fires?
As the other commenter said, Halon hasn't been a thing for a fair while, but inert gas fire suppression systems in general are still popular.
I would expect it wouldn't be sufficient for a lithium ion battery fire - you'd temporarily displace the oxygen, sure, but the conditions for fire would still exist - as soon as enough nitrogen (or whatever suppressant gas is in use) dissipates, it'd start back up again.
Also as I understand thermal runaway is self-sustaining, since the lithium ion batteries have a limited capacity to provide their own oxygen (something to do with the cathode breaking down?), so it might continue burning even while the area is mostly flooded with inert gas.
I believe it would be similar to an EV car fire, that is, you'd have to flood the area with water and wait for it to cool down enough that thermal runaway stops. Maybe they can do better these days with encapsulating agents but I'd still expect the rack housing the UPS to be a write-off.
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They were not tested enough for that. From chemical POV the fluorine in halon can even exothermically react with lithium, like teflon can with aluminium. But all depends on circumstances, it needs high temperatures and the lithium concentration in batteries is low.
I'm not sure about South Korea, but in the U.S., halon started to be phased out in 1994 due to its ozone-depleting characteristics. I believe new facilities use CO2.
I'm guessing lithium-ion batteries were not a factor years ago when those decisions were made.