I have a gas reservoir holding hydrogen from my SPOM. When it's full the gas passes the input and vents into an infinite gas storage room where it can be pumped out later if the reservoir goes empty. The output of the reservoir has a gas bridge linking into it from the gas pump in the infinite reservoir. This should only allow gas to be pumped into the pipe if the reservoir is empty, but it is not. It appears to be due to the fact that the pipe segment in the output port of the reservoir only holds 200g instead of 1000g, so when the gas moves, the second segment with the pipe bridge feeding into it only gets 200g from the reservoir so it has room for another 800g from the pipe bridge.