Well, this is not much of a bug, more of a feature request:
If we build a Gas pipe line from one room to another, the room with the higher pressure should force the gas inside the pipes without a pump and the gasses should flow from one room to another.
To make this easy to develop (developer here), you could create a handful of "vents", one that allows gas in but not out, one that allows out but not in, and another that would allow gas flow in or out depending on pressure.
The logic of the vent could measure the pressure between the entrance (tile n-1) and the next tile (n) so, if the pressure on n-1 > n, acts like a pump. If n>n-1, acts like a vent.
Seems dumb, but it would make our life's way easier!
Create a room with 2k O2 pressure, put a vent and a pipe connecting such vent into a second room with vacum.
The O2 should flow from room 1 to room 2.