Let welders be refilled from fuel canisters.

[Roomba]

Making chemthrowers isn't especially difficult, even if you felt the need to do it secretly for some reason. The most time-consuming part is making the actual chems. Not being able to empty out the tank in one go saves you at most twenty to thirty seconds of spraying unlit fuel at a wall.

Also in a station in which these are ostensibly supposed to have some kind of practical use, it doesn't make sense that the only method of emptying them is flamethrower related.