Question
Does velocity through different pipe diameters translate into different distances through a sprinkler head once it leaves the pipe? That is, will 6 gallons going through  3/4" cl. 200 PVC travel further through a sprinkler head than 6 gallons going through 1 1/2" PVC?

Answer
Steve, this is one of the best questions I've gotten so far. Yes, velocity does matter. Six gallons going through three quarter would have more "friction loss" than through an inch and a half pipe. There are many variables though. For instance, length of pipe and pressure. If you had five feet of three quarter pushing six gallons at 45 psi than your pressure loss per foot would be 0.019 as opposed to 0.0018(approx.) through inch and a half. So, to answer your question, six gallon going through lets say five feet of pipe at lets say 45 psi to a single head would travel farther through inch and a half. I hope this helps and once again, nice question!!