Does anyone know how to calculate the size and pitch of PVC piping to get X amount of water flow.

I have 41 coolers in my warehouse and a few do not get enough water and I think its because of the way they piped them. I have a 10HP Armstrong pumping the water up. It is a 32 foot rise. They go from 4 inch pipe to 3 inch down to 1 inch by the time it gets to the unit. The 1 inch is a 4 foot rise up through the roof with a single ball valve at the top. The units that are not getting enough water are NOT farthest from the pump.

Every intersection is a "T" and the only elbows in the system are on the main supply line.