Catch can data from the first 20 percent of the system length closest to the center pivot point should be ignored. The “average catch can (ml)” data replaces the first catch can data points. The actual “distance from center point” is entered for the first data point (remaining after deletion of other points closer to the center pivot point). Coverage near the center point of the system represents such a small amount of the total system coverage deviation from the average, that it yields little effect on the machine’s overall uniformity.
Catch can data from the outer edge of the wetted area is deleted from the data set when the volume is less than 70 percent of the average. Removing the data that tails off at the outer edge of the system designates the effective irrigated area, and avoids dilution of the data points representing the actual targeted irrigated area.
Up to three percent of the data points should be removed if it is an extreme deviation from the average. This is done after the outer edge data has been removed to define the effective irrigated area and up to 20 percent of the inner area data has been removed. A few catch cans could collect extreme data that is not representative of the system area, like water running from a trust rod or brace rod directly to the cup.
Cleaning the Data
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