Paul you can use 1 to carb, 1 to fuel dot and 1 for a vent. OR 1 to carb with a tee to dot and 1 for the vent, this is the way I have my DA 50 configured. I have the tee 1 inch from the carb so when I am done fueling the lines are full of fuel, choke on , 6 flips , choke off, ing on , starts on the second flip. Both systems work well. The carb has a built in diaphragm pump, no pressure line needed.

Kent