12
UPSIDE-DOWN MICRO-EMITTERS HANDBOOK
MICRO-SPRINKLER/EMITTER SELECTION
Advantage of the %DU method:
The measurement of %DU takes the driest results into account. Therefore it is better than %CU, as it
compares the area that receives the least water with the average application of the entire area.
Calculating %DU
1.
Gather the water levels previously collected in each gauge or can (mm) [a].
2.
Sum all the numbers in column [a].
3.
The sum is divided by the number of gauges or cans placed. This provides the average net application of
the entire surveyed area [b].
4.
The lowest 25% of the numbers in the column are summed up.
5.
The sum of the lowest 25% of the numbers in the column is divided by 25% of the number of gauges
or cans placed. This provides the average net application of the lowest 25% of the numbers
representing the surveyed area [c].
6.
The average net application of the lowest 25% of the numbers is divided by the average net application
of the entire surveyed area. This provides the DU of the surveyed area as a percentage (%) [d].
EXAMPLE
a b c d
Net application
measurements [mm]
Average net
application of the
entire area [AVG]
Average net application
of the lowest 25%
[AVG low] %DU
5.14
91.35 / 20 = 4.57 19.81 / (20 x 25%) = 3.96 (3.96 / 4.57) x 100 = 86.65
5.06
5.02
4.99
4.87
4.87
4.83
4.77
4.75
4.73
4.70
4.62
4.41
4.40
4.38
lowest 25%
4.26
4.25
4.12
3.82
3.36
Sum - entire area:
91.35
Sum - lowest 25%:
19.81
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