My pressure is around 70 psi. The system was designed by a professional, and I really don't recall how many gmp's each zone uses, but I run 9 Rainbird impact sprinklers on each zone with no problem. The pipes start from the valve box with 1-1/4", drop to 1", then to 3/4" during the course of the runs. This is further reduced to 1/2" going into the sprinkler. I was told this has to do with friction loss. I can't answer your question for certain about the drip systems as I have never used one. I would assume however, you would have to open the ends to blow the water out. I'd suggest you speak to an irrigation installation company about that if you don't get an answer of this forum. I'd really hesitate to just apply air pressure to a drip line that was closed. Oh yeah, if I haven't already mention this, I have a 1" meter and it is piped to the backflow with 1" copper. There is about a 30' run from there to the valve box and that is with 1-1/2" just after leaving the backflow preventer.