Full Product Manual

Table Of Contents
2.Determine Maximum Run Time
The maximum system run time is the length of time the system can run before
you begin to waste water due to deep percolation loss below the desired water-
ing depth. To determine the maximum system run time, you must know the flow
rates of the emitters and the allowable depletion of the soil.
Allowable depletion is the percentage of soil moisture that you will allow the
plants to deplete before watering again. If you select a lower allowable depletion
percentage, you initiate a watering cycle when just a small amount of moisture
has been depleted. Watering will occur more frequently but for less time at each
irrigation cycle. A higher allowable depletion will require fewer irrigations,
providing more water at each irrigation. Generally, allowable depletion should
not exceed 30-50 percent for a low-volume irrigation system.
Use Tables 6-2 through 6-4 to estimate the maximum run time for your system
and make a note of it. Use the table for the soil type in your site. These tables are
based on an allowable depletion of 30 percent. For calculations based on other
allowable depletion percentages, see Appendix A.
Page 46 Chapter 6
TABLE 6-2: MAXIMUM SYSTEM RUN TIMES FOR COARSE SOIL
Watering Depth Emitter
Spacing
Emitter Flow
(GPH)
Maximum Run
Time
3 inches
6 inches Use Xeri-Sprays, Xeri-Pops or 1800 Spray Heads
9 inches
12 inches 12 inches 0.5
1.0
2.0
37 minutes
18 minutes
9 minutes
18 inches 18 inches 0.5
1.0
2.0
145 minutes
62 minutes
31 minutes
24 inches 24 inches 0.5
1.0
2.0
296 minutes
148 minutes
74 minutes
Available Water = 1.4"/ft.; Application Efficiency = 85%; Allowable Depletion
= 30%
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