Dave,
This was the first bladder tank I have installed. I must say that it sucks out every ounce of fuel. It has two lines a vent line and the fuel feed. I cut a tee into the feed to fill with a fuel dot. I have the vent line plugged all the time only remove it to fuel up and when fuel comes out I plug it to fly. On the side of the tank is a vent or spill line if the bladder breaks ? Not sure here which is plumbed out and down that is not plugged.

Chris