[jabl]

Engine rooms in ships typically have CO2 systems. There's been several fatalities when crew have reentered the space before the CO2 has been ventilated away. Made worse by CO2 being heavier than air so it can remain in some crawlspace under the engine frame or such.

[cyberax]

Yep. Found that safety video: https://youtu.be/NrP5-E9jmas?t=344 - I was misremembering it a bit.

It's really unfortunate that halon is so dangerous for the ozone layer, none of the replacements are as good as it was.

[jabl]

High-pressure water mist systems seem pretty good, including being usable in spaces with lots of electrical stuff like machine rooms and data centers.

https://www.marioff.com/en/

[cyberax]

Second 292 for the demo.