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Sprinkler Irrigation in the
Landscape II
Solve problems to have a really good irrigation system
Source of water
- What are the three common sources of water for South Florida landscapes?
Well,
surface (pond or canal), municipal treated, and _________.
- What are the potential problems associated with each source?
[Water quality, price,
pressurized or not.]
- A pump provides what two things to an irrigation distribution system?
________________ and ________________
- What are the three commonest ways of activating a pump?
Manual,
pressure sensor, and timer.
- What are two ways of using a timer to activate a pump?
(a) Pump start switch is activated with the initiation of the irrigation cycle.
(b) Pump is started and stopped at intervals for each zone; allows for a means to open
and close off zones that originate at a distributor.
- What are the parts of a suction line and what do they do?
Filter,
check valve, culvert, grating, unions, pipe.
- What are the accessory parts of a pump station besides the pump?
Pressure
and heat sensors, flow monitor, clay valve, shut off devices.
Main line
- How does the shape and size of the landscape affect the possible
arrangements for a main irrigation line? What are the possible arrangements of a main
line?
- What are the special problems in maintaining a main line?
(a) If system is pressurized, there is no tolerance for leak
(b) Pipe is large diameter, fittings are large, inflexible, and expensive, making
in-line repairs difficult and expensive with little tolerance for error.
(c) Pipe is deep and often hard to get at, sometimes in contact with rock, underneath
roads, close to other utilities, and vulnerable to damage by other construction work.
(d) Special provisions must be made that valve boxes and covers are safe and can be
maintained.
- What are special solutions to problems of a main line?
Valves, maps, inspections, proper installation (use a string line).
Zones (valves, pipes, and heads)
- Define an "irrigation zone."
- What are the two purposes of an irrigation zone?
- What is a sample formula for the maximum size of an irrigation
zone?
area = pump capacity / precipitation rate
Unfortunately, there will be a problem converting units, but if the pump capacity is in
gpm (gallons per minute), the precipitation rate is inches per hour, the area in thousand
square feet will be:
area (K) = 60 * 12 / 7.48 gpm / ppt (inches/hr)
= 96 gpm/ppt or about 100 gpm / ppt
- A rainbird 15 series nozzle is similar to other spray head
nozzles that are widely used. At 30 psi (pounds per square inch) the full circle form 15F
will cover 15 feet radius and deliver 3.70 gpm. If we vary the spacing between heads, how
will this affect:
(a) gallons per head
(b) the ppt (precipitation) rate
(c) the number of heads per area
(d) the uniformity
- What are the important table values for an irrigation head?
- An irrigation zone has nine sprinkler heads, one 15F and eight
other heads, half-and quarter-circle, with matched precipitation. Draw the irrigation plan
and answer the questions which follow.
What is the total gpm at 30 psi?
Assume the area is supplied by a 1" Class 160 PVC pipe, and the main line is 100
feet between the source and the valve, what is the pressure loss?
What is the main reason that this is an estimate, not a final value?
What are other reasons that this is an estimate?
Trouble shooting, retrofitting
- The first thing to check following an irrigation leak is:
- What is the first steps to "tune" an irrigation system?
- Assume that an irrigation system provides poor uniformity of
distribution, what are the possible causes?
- Why does the irrigation designer need to know something about the
site?
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