At the beginning of the season, the installation will have to be drained and checked to ensure that it is in good working order (rotation, obstructions) and the end gun properly adjusted (range and angle of the throw specified in the spray nozzle design chart/Sprinkler Package).
Secondly, using a portable pressure gauge, it is important to check the pressures at the inlet and at the end point. These pressures must comply with those specified in the nozzle design chart/ Sprinkler Package (do not leave the pressure gauge permanently connected to the installation).
The alignment of the spans must also be checked (against each other).
During the season, the pressures at the inlet and at the end point must be checked and it must be confirmed that the sprinklers and end gun are working correctly (rotation, obstruction, end gun shut-off device). If the pressures are different from those specified in the chart, the flow rate will vary and thus the amount applied will change and the water distribution will be poor. These measurements must be carried out regularly and they are essential when changing a nozzle.
Finally, the amount applied can be calculated as follows:
D= Q/S x 2nxR/Vx10
Q: Flow rate at the intake of the system in m³/h
S: Surface area irrigated (ha)
V: Average forward speed of the last tower (m/h)
R: Distance between the pivot’s centre axis and the last wheel (m) ?: 3.1416
In the case of a device operating by sector, correct S and R, without forgetting the time required for the machine to complete the return run. For an end gun that only operates intermittently, only correct S.
A nozzle and the sprinklers have an average life span of 5 to 10 years.
An irrigation system can be considered to be efficient if an appropriate amount of water is applied. This should take into account the soil properties (water storage capacity, permeability) and the precipitation rate applied during irrigation and the crop water requirements must be met during the peak periods.