Distance - Speed
0 pipes - 240 fluid/sec
4 pipes - 150 fluid/sec
14 pipes - 120 fluid/sec
224 pipes - 90 fluid/sec
357 pipes - 60 fluid/sec
759 pipes - 30 fluid/sec
This limit reduces the capacity of long pipes. Pipe-to-ground helps, it counts as 1 pipe and can reach 5.5x as far. But even pipe-to-ground slows down if you stretch it too far.
The solution is small pumps!
Small pumps pressurize a pipe until it is full again, allowing you to stretch pipes as far as you like without losing speed and capacity. Just remember to put a pumping station before your flow rate drops too far, because once it drops below the limit it is impossible to speed up again.
Each small pump can only handle 30 fluid/sec, so you need to use them in parallel.
Speed - Pumps needed - Distance between pumping stations
30 fluid/sec - 1 pump - 759 pipes
60 fluid/sec - 2 pumps - 357 pipes
90 fluid/sec - 3 pumps - 224 pipes
120 fluid/sec - 4 pumps - 14 pipes
150 fluid/sec - 5 pumps - 4 pipes
Here are the optimal designs for each size pumping station.