system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do divers wear their oxygen bottles with the exit valve pointing up, but firefighters with the exit valve pointing down?

Shouldn't the pressure always force the air out of the exit valve, regardless of its orientation? What is the reason for this?
gpt
Divers are going to watch their heads and are in a mostly open area with very little heavy falling debris, so putting the oxygen valve up near the head allows it to be safer in the case of cramped spaces, and limits the hoses required to get the oxygen to the facemask.

Firefighters have to worry a lot more about falling debris and dangling wires and pipes, and worry less about the pressures of being underwater, so they use a longer hose and put the tanks on valves down, so a falling beam is more likely to strike the sturdy bottom of the tank and not the relatively fragile valves that release oxygen.