OK I think I get what you wrote but the tank's interconnector tubes are quite large enough to allow the liquid and the vapour to disperse through all 3 cylinders at normal operating angles. There are 1" tube connectors at the top right, 2" in the middle (both sides) and 1" at the bottom left of the cylinders to allow quick equalisation. Also the filling flow rate is somewhat reduced on these things to allow for that. The float valve being at the slightly lower (right hand) end of the tank will have a far bigger effect on filling than any venting issue.

