Full Product Manual

Table Of Contents
Formulas for Xerigation Design Page 79
Once you calculate the system run time and the maximum run time, you can
determine how often to run the system.
Maximum Irrigation Interval (days) = Maximum Run Time
Calculated Run Time
The general formula for system run time is:
Run Time (hours) = Water Requirement
Flow
However, since the water requirements are measured differently for sparse
plantings and dense plantings, you must apply the formula differently.
Dense Planting Scheme
The formula for system run time for dense plants is based on a measurement of
flow in inches per day. We call this measurement “Emitter Discharge Rate” or
EDR. EDR is measured in inches per hour.
The formula for determining EDR is:
EDR (inches per hour) = 231.0 x q
s x l
Where:
q = emitter flow rate (gallons per hour)
s = emitter spacing (inches)
l = lateral spacing (inches)
EDR must be further adjusted by multiplying it by the application efficiency
(percentage) to arrive at “Adjusted EDR.”
The formula for system run time for dense plantings is:
Run Time (hours) = Water Requirement (inches per day)
Adjusted EDR (inches per hour)
System Run Time
Irrigation Interval
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