TWENTYNINE PALMS, Calif. — Nearly two dozen Marines were treated for exposure to a fire retardant gas Thursday after an extinguishing system accidentally went off in an assault vehicle during a training exercise, but there were no serious injuries, officials said.
An equipment malfunction caused the fire suppression system to go off inside a tank-like amphibious assault vehicle during an afternoon exercise at the Marine Corps Air Ground Combat Center in Twentynine Palms, base spokesman Dave Marks said.
There was no fire or explosion but 22 Marines were exposed to halon, Marks said.
All of them were taken to the base hospital. Three were kept overnight for observation and the rest were released to resume training, Marks said.
Halon discharges are fairly common, usually the result of some dumbassery on the part of a junior troop (face reddens a bit here).
We’ve noted before that armored vehicles tend to be filled with a lot of very flammable things, such as fuel, ammunition and people. It only makes sense to provide a robust fire suppression system. Older systems used CO2. The problem with CO2 was that a sufficient concentration of it was enough to not only extinguish the fire, but also rapidly extinguish the crew. Halon works better at suppressing a fire while also allowing the crew enough oxygen to breath long enough to abandon the vehicle.
The primary goal of the fire suppression system is to save the crew. If it also saves the vehicle, that’s a bonus.
In peacetime, the fire suppression system is (usually) manually initiated. There are internal and external “T” handles that are pulled to discharge the Halon.
In combat, there an automatic system. Sensors inside the vehicle detect an explosion and almost instantly unload the Halon. It’s… loud. It doesn’t take long at all for the bottles to empty. More of a “boom!” than a “whoosh.”
Ships use similar fire suppression systems in their engineering spaces, though I have no idea what the current agent used is.