The guys who worked with it always had breathing systems nearby and preferred to do servicing outside, rather than in a hanger.

We used it in all the computer rooms I worked in, which all all air tight doors and positive pressure to keep out contaminates. They told us there was a 1 minute delay, but I don’t know anyone who wanted to time it from inside.

The hatches must have been shut, and they probably lock when the system starts dispensing the halon.

Normally in a fire you drop and crawl because carbon monoxide is lighter and rises to the top, but that is exactly the wrong thing to do with halon.

It was new vessel testing – things rarely work correctly with anything as complex as a submarine, or an aircraft.