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Layout ConsiderationLayout Consideration
ObstaclesObstacles FencesFences Power linesPower lines Out buildingsOut buildings DitchesDitches RoadsRoads WindWind
SlopeSlope
With the slope vs. Cross slopeWith the slope vs. Cross slope
Laterals are generally laid out Laterals are generally laid out perpendicular to the slopeperpendicular to the slope
Set TimesSet Times
Convenient set times Convenient set times 23.5 hrs23.5 hrs 11.5 hrs11.5 hrs 7.5 hrs7.5 hrs
* Allows ½ hour drain time* Allows ½ hour drain time
7.5 hr not popular . One move allways in the 7.5 hr not popular . One move allways in the darkdark
Lateral set sequencingLateral set sequencing
Irrigate every move across the field roll Irrigate every move across the field roll back to the front and start againback to the front and start again
Skip irrigate every other move irrigate the Skip irrigate every other move irrigate the skipped moves on the way backskipped moves on the way back
Irrigate every move across the field Irrigate every move across the field second time use a offset pipe. Alternate second time use a offset pipe. Alternate back and forthback and forth
UniformityUniformity
Affected byAffected by Base PressureBase Pressure Pressure variationPressure variation OverlapOverlap Application RateApplication Rate WindWind
Base pressureBase pressure
Match spacing to pressure Match spacing to pressure
Rule of thumbRule of thumb 45 to 65 psi – 40x60 and 40x5045 to 65 psi – 40x60 and 40x50 35 to 45 psi – 30x40 and 40x4035 to 45 psi – 30x40 and 40x40 25 to 35 psi – 20x30 and 30x3025 to 35 psi – 20x30 and 30x30
Drains may not operate properly under Drains may not operate properly under 24 psi24 psi
Pressure VariationPressure Variation
Affected byAffected by Elevation differenceElevation difference
Up and down slope vs cross slopeUp and down slope vs cross slope Mitigate with flow control nozzles or pressure Mitigate with flow control nozzles or pressure
regulatorsregulators Friction lossFriction loss
Pipe sizingPipe sizing
Limit pressure variation to 20% of design Limit pressure variation to 20% of design operating pressureoperating pressure
OverlapOverlap
Rule of Thumb
50% along lateral
65% between laterals
Example:
40x50 spacing
Sprinkler diameter would need to 77’
Application RateApplication Rate
Too small – wind problemsToo small – wind problems Too Large runoffToo Large runoff
Match to soils and Irrigation intervalMatch to soils and Irrigation interval
WindWind
CausesCauses Poor uniformityPoor uniformity
Fine spraysFine sprays High pressuresHigh pressures High trajectoryHigh trajectory
Structural damageStructural damage
Wind SolutionWind Solution
Low trajectoriesLow trajectories Low pressureLow pressure Course spraysCourse sprays OffsetsOffsets BracesBraces
Example of multiple Example of multiple passespasses
0 10 20 30 40 500
1
2
3
4
5
distance along travel path
application depth
Pass 1 Pass 2 Pass 3 sum
MaintenanceMaintenance
NozzlesNozzles GasketsGaskets DrainsDrains LevelersLevelers Springs/rotationSprings/rotation
LayoutLayout
Hose dragHose drag Solid setSolid set
Rectangular vs. triangularRectangular vs. triangular
Typical hose drag layoutTypical hose drag layout
Travel lanes
Connectionto main
Buried or Portable main line
Up to ¼
mile (1320’)
Traveler direction
Trajectory angleTrajectory angle
Optimization of pattern uniformityOptimization of pattern uniformity Minimize wind driftMinimize wind drift Maximize radius of throwMaximize radius of throw Best drop conditionBest drop condition
Application RateApplication Rate
Match to soilMatch to soil RunoffRunoff SealingSealing
ftft
gpmgunhrin spacing LinespacingGun
Q3.96Raten Applicatio
PressurePressure
60 psi minimum60 psi minimum
WhyWhy Throw distanceThrow distance Stream breakupStream breakup
Crop and soil damageCrop and soil damage
Riser AssemblyRiser Assembly
VerticalVertical Stable against vibrationStable against vibration Low turbulenceLow turbulence Protected from animals and machineryProtected from animals and machinery
Thrust Thrust
CausesCauses TippingTipping VibrationVibration Fatigue and damage to jointFatigue and damage to joint
SolutionSolution Aluminum tripodAluminum tripod Concrete blockConcrete block Post Post Swing elbowSwing elbow
StabilityStability
With a stable riserWith a stable riser Drive arm works properly and increases Drive arm works properly and increases
uniformityuniformity Vibrations are dampened protecting pipeVibrations are dampened protecting pipe Stream throw radius is maximized giving Stream throw radius is maximized giving
greater coveragegreater coverage
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