Irrigation Systems and Components

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Irrigation Systems and Components
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Overview

• Types
• Layout
• Components
• Hydraulics
• Design Considerations

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Functional Irrigation System

• Good Design
• Good Installation
• Regular Maintenance
• Water Management

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Conceptual Layout
From Water Supply
Chemical Tank
Filter
Flow Meter
Main Line
Drip Lines
Manifold
Valve/Pressure Regulator
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Micro System Components

• Pump (or gravity) 5-20 psi range (at emission
  point)
• Chemical injecting device
• Filtering system
• Mainlines/Submains (PVC)
• Laterals (drip line)
• Emitters
• Control valves/air and vacuum valves/regulators/wa
  ter metering

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Turbulent Flow Tape/Tubing
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Pressure-Discharge Relationships
Sprinkler
Drip Emitter
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Application Rates
I, iph q, gpm Sl, Sm, feet
Sprinkler
Operating hours Fg/I Fg gross irrigation depth
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Irrigation System Application Rates
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Drip, Operating Hours
T- hours Ww, wetted width, ft Fg , gross
irrigation depth, inches q, drip line discharge,
gpm/100 ft
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Pressure Variation
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Pressure 8psi Slope level EU72.5
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Pressure 8psi Slope level Length 500
feet EU91.9
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Pressure 8psi Slope 1 downhill Length 1,000
feet EU82.4
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Friction Loss

• Rule of Thumb, limit velocity to 5 fps
• Keep pressure variation within 20
• Equations
• Darcy-Wiesbach
• Hazen-Williams
• Can balance capital cost of pipe against energy
  costs to overcome friction

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Filter Types

• Media (Primary)
• Higher flow rates
• biological filtration
• Screen (Primary or Secondary)
• Lower flow rates
• Cheaper
• Disk (Primary or secondary)
• Number of cartridges per flow rate

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Screen Size
Fine Sand
Silt
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Filtration
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Air/Vacuum valves

• Prevent ingestion of soil particles for SDI
• Prevent water hammer
• Keep air out of system
• Prevent collapsing of pipe

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Pressure Regulation

• Reduce pressure from main/sub-main
• Set to tape/emitter specs
• Regulator for each zone or subunit

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Pumping Requirements

• Flow
• Head (Total Dynamic Head - TDH)
• Operating Pressure
• Friction Losses
• Elevation Difference
• Static Lift

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Pump Horsepower Requirement
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NPSHR
Pump Curve
Efficiency
80
Power
400
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NPSHR
Pump Curve
Efficiency
80
System Curve
Power
400
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Irrigation System Costs