The hydraulic design and the structure’s design work closely together.  

The recommended maximum number of sprinklers on a 25mm pipe (26.5mm – internal diameter) is 5. This number keeps friction loss over the lateral to 5 meters or 5 Bar (50kPa). The recommended maximum spacing between sprinklers is 15 meters, resulting in a maximum span of 75 meters. The weight of the water and the pipe at 0.73kg per meter; give an evenly distributed load of 55kg.

If the number of sprinklers is increased to 6, the friction will increase to 8 meters. A 32mm pipe is required if the friction loss is to be kept to an acceptable 5 meters. The load on the structure is very nearly doubled using 32mm pipe, therefore a 25mm pipe and a maximum span of 75 meters is recommended.

Graph 7.1 - indicates the friction loss in lateral pipes with differing numbers of sprinklers on a line.