Full Product Manual

Table Of Contents
Table 5-8 provides the area wetted by emitters in the most common spacing
patterns.
Area Wetted (sq. ft.) = Emitter Spacing (ft.) × Emitter Spacing (ft.) × 0.7854
Given your soil type, select the appropriate emission device to avoid runoff.
Next, determine the suggested spacing of your emitters based on the soil type
and the desired watering depth. Use Tables 5-4 through 5-6 as a guideline. Next
determine the area wetted by each of your emitters. The formula for the area
wetted is:
Calculating the
Wetted Area
Page 40 Chapter 5
The minimum area to be wetted is a function of the plant’s root zone. For most
plants you can assume that the area of the plant’s root zone is approximately the
same as the area of its canopy. In general, the minimum area to be wetted should
be one half of the area of the plant’s mature canopy.
To determine the number of emitters required for each plant, divide the mini-
mum area to be wetted by the area wetted by each emitter:
Minimum number of emitters = Minimum Area to be Wetted (sq. ft.)
Area Wetted by Emitter (sq. ft.)
EXAMPLE
You are designing for a hydrozone that contains six azalea shrubs, each with
a mature canopy of 4 feet, and two crepe myrtle trees, each with a canopy
diameter of 10 feet. The soil type is coarse. The azaleas require 0.4 GPD and
the crepe myrtles require 3.3␣ GPD. The azaleas, with the lowest water require-
ment, are the base plant.
Table 5-4 shows that the desired watering depth for small shrubs is approxi-
mately 18 inches. Table 5-6 shows that to reach a depth of 18 inches in
coarse soil, you should space emitters 18 inches apart.
Table 5-8 shows that emitters spaced at 18 inches in coarse soil will each wet
1.8 square feet.
TABLE 5-8: AREA WETTED BY EACH EMITTER (SQ. FT.)
Emitter Spacing Coarse Soil Medium Soil Fine Soil
12" X 12" 0.8 1.6 3.1
18" X 18" 1.8 3.5 7.1
24" X 24" 3.1 6.3 12.6
36" X 36" 7.1 14.1 28.3
®