Nelson BIG GUN 75 Series User manual

BIG GUN®SOLUTIONS
Portable / Solid Set Irrigation
09/24/2021
PORTABLE / SOLID SET IRRIGATION APPLICATION GUIDE

PORTABLE / SOLID SET

CONTENTS
Big Gun®Sprinkler Models................................ 4
Overview ............................................... 5
1. Design Guidelines ......................................7
1.1 Sprinkler Selection .......................................8
1.1.1 Connections ..............................................8
1.1.2 Portable Systems with the QC Valve/Key .................9
1.2 Trajectory...............................................10
1.3 Nozzle and Pressure.....................................11
1.3.1 Secondary Nozzle .......................................12
1.4 Spacing and Uniformity ................................13
1.4.1 Application Rate .........................................14
1.5 Water Quality ...........................................14
1.6 Operation ..............................................15
1.7 Rotation Speed ........................................16
1.8 Riser Design ...........................................17
1.8.1 Hydraulics ...............................................17
1.8.2 Stabilization and Thrust.................................18
1.8.3 Straightness ............................................18
1.8.4 Material .................................................21
1.8.5 Height and Protection ..................................21
1.8.6 Air Relief, Pressure Relief, and Isolation .................22
1.8.7 Drain-down .............................................22
1.9 Riser Examples ........................................23
1.9.1 Portable Systems........................................23
1.9.2 Permanent Systems ....................................23
2. Design Examples .......................................25
2.1 Manual vs Automatic Systems .........................25
2.1.1 Portable, Manual.........................................26
2.1.2 Semi-Automatic (Automated, Portable)..................27
2.13 Automated Solid Set ....................................28
2.2 Center Pivot Corners...................................29
2.3 Sports Fields ...........................................30
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Big Gun®Sprinkler Models
Notes:
1. Not available on SRNV100
2. Use Nelson Flange x Threaded Adapter: 150FI, 3” or 3.5” FNPT/FBSP; or 150/200FI, 4” FNPT.
3. Use Nelson Flange x Threaded Adapter: 150/200FI, 4” FNPT.
4. For ANSI connection, use Nelson x 4” ANSI Flange kit (#12807)
5. Not available on SR75.
6. Works with SR100 and SRA100 only.
7. SR200 only
75 SERIES 100 SERIES 150 SERIES 200 SERIES
FLOW 25-160 GPM
(6-36 M3/H)
40-300 GPM
(9-70 M3/H)
90-630 GPM
(20-143 M3/H)
230-1200 GPM
(52-272 M3/H)
PRESSURE 25-80 PSI
(1.75-5.5 BAR)
40-110 PSI
(2.75-7.5 BAR)
50-120 PSI
(3.5-8.25 BAR)
50-130 PSI
(3.5-9 BAR)
MODEL &
TRAJECTORY
Full Circle
F75
Part Circle
SR75
Full Circle
F100
Part Circle
SR100
Part Circle
SRA100
Full Circle
F150
Part Circle
SR150
Part Circle
SRA150
Full Circle
F200
Part Circle
SR200
21°, 24° 18°, 21°, 24°, 43° 18°, 21°, 24°, 43° 15-45°
Adjustable
18°, 21°,
24°
21°, 24°,
27°, 43°
15-45°
Adjustable 21°, 24°, 27° 21°, 24°, 27°,
33°, 36°, 39°
NOZZLE
OPTIONS
TAPER
-100T
(10 sizes)
150T
(8 sizes)
200T
(9 sizes)
TAPER RING
75TR
(9 sizes)
100TR1
(11 sizes - Aluminum or Plastic)
150TR
(17 sizes - Aluminum or Plastic) -
RING
-100R1
(8 sizes)
150R
(7 sizes)
200R
(7 sizes)
THREADED
CONNECTION
1.5” FNPT / FBSP
2” FNPT / FBSP
2” FNPT / FBSP
2.5” FNPT1Adapter Required2Adapter Required3
FLANGE
CONNECTION 2” ANSI/DIN / Nelson / Euro ” ANSI/DIN/ Nelson1/ Euro13” ANSI/DIN / Nelson / Euro 4” Nelson / Euro.
ANSI Adapter4
4” ANSI/DIN /
Nelson / Euro
SPECIAL COATING
/MATERIAL -Anodized,
Anodized & Powder Coated
Anodized,
Anodized & Powder Coated,
Stainless Steel
Anodized,
Anodized & Powder Coated
SPECIAL
OPTIONS -
Euent Bearing Assembly,
Vaneless Range Tube,
Brakeless
Euent Bearing Assembly,
Vaneless Range Tube Euent Bearing Assembly
ACCESSORIES
Dust shield5,
Counterbalance kit,
12° wedge kit
LP drive vane6,
Dust shield,
Counterbalance kit,
12° wedge kit
-Counterbalance kit,
12° wedge kit -
Counterbalance kit,
12° wedge kit,
Manure/Large Nozzle kit7
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• Agricultural Irrigation
• Irregular Field Shapes
• Center Pivot Corners
• Sports Fields
• Horse and Livestock Pastures
• Mining and Industrial Dust Control
Why Choose a Nelson Big Gun®Sprinkler
OVERVIEW
Primary Applications
• The Big Gun®name is synonymous
with the best quality available.
• Heavy-duty construction ensures long
wear life & reliability.
• Greatest range of options. Full & part-
circle sprinklers available in a variety of
trajectory, nozzle & coating options.
• Integrated control valves with wireless
automation available for maximum
system eciency.
• Easy to operate, maintain and repair
with readily available parts and
documentation.
F75 / SR75 24F100 / SR100 24F150 / SR150 24
Secondary Nozzles 800 / 1000 / QC Valves
KEY PRODUCTS & ACCESSORIES
TWIG®Wireless Controls
Portable / Solid Set Irrigation
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OVERVIEW
Portable / Solid Set Irrigation: Overview
Nelson Big Gun®sprinklers are a great option for portable, solid set, and permanent set systems in
agricultural irrigation, irregular field shapes, sports fields, and more. This application guide contains
design guidelines, examples, and best practices for using Big Gun®sprinklers in these applications.
“Set” sprinkler irrigation systems operate with the sprinklers set in a fixed position (as opposed to
mechanized or continuous-move systems such as center pivots and hose reel travelers). There are
two main types of “set” systems:
• Portable set (also called “periodic-move”) systems where sprinklers must be moved
through a series of positions over the course of irrigating a field;
• Solid set systems that do not require the sprinklers to be moved during the course of
irrigation.
Portable systems may involve moving just the sprinkler or an entire lateral across the field. The
system may be composed of buried pipe, with one or a few sprinklers that are moved from riser
to riser, with only one sprinkler operating at a time in order to reduce the required pipe diameter.
Alternatively, portable systems may use just one or a few lateral pipes that are moved across the
field during the course of irrigation.
The mainline and laterals in solid set systems may be above ground, portable pipe that is left
in place throughout the duration of the irrigation season, but removed only during cultivation/
harvesting. This would be called a “portable solid set” system. Alternatively, “permanent solid set”
systems use buried pipe.
ADVANTAGES OF PORTABLE
SYSTEMS:
• Pipe can be removed from the field for
farming operations, which eliminates the
necessity of farming around sprinkler risers.
• In its most basic form the portable sprinkler
concept is one of the lowest cost systems
available.
• Portable systems can be rotated to dierent
fields to follow the crop rotation.
• Portable systems make land leasing
programs practical.
ADVANTAGES OF PERMANENT SOLID
SET SYSTEMS:
• Selection of the sprinkler spacing is not
limited by standard portable pipe lengths.
• There is less irrigation labor involved, as the
pipe does not have to be moved out of the
field for farming operations.
• It is possible to loop the piping system, which
aords some economies through pipe size
reduction.
• Supporting the sprinkler riser is less
complicated than with above-ground pipe.
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Portable / Solid Set: Design Guidelines
1. DESIGN GUIDELINES
• Sprinkler Selection
• Trajectory
• Nozzle and Pressure
• Spacing (application rate)
• Water Quality
• Operation
• Riser Design
• Rotation Speed
In order to provide the best crop yield and health, agricultural irrigation systems should be
designed for high uniformity and water eciency. Other factors such as system cost, operating
cost, durability, and labor deserve consideration. Use of an irrigation design software, such as
IRRICAD, is strongly encouraged. A properly designed Big Gun®sprinkler system is capable of
achieving high uniformity and will last for decades when the following factors are considered:
Figure 1. The Big Gun®sprinkler family: (from left to right) 200 Series, 150 Series, 100 Series, 75
Series.
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1.1 SPRINKLER SELECTION
• 75 and 100 Series are most commonly used models.
• Specify the correct connection to be compatible with the riser.
The 75 Series and 100 Series Big Gun®sprinklers are the most commonly used models for
portable and solid set systems. They oer the best balance of required pipe diameters, application
rate, operating pressure and sprinkler spacing. The 150 Series Big Gun®sprinklers have larger
nozzles that allow for a wider grid pattern, however the required flow per position increases to a
greater degree than the increased spacing. Thus, higher pressures and larger diameter pipes are
required, increasing the overall cost. The 200 Series is not commonly used in this application.
1.1.1 CONNECTIONS
The sprinkler connection type must be specified and should be compatible with the riser design.
When Nelson control valves are used in conjunction with Big Gun®sprinklers, the ANSI flange is
the ideal connection. Otherwise, threaded connections are available for 75 and 100 Series. The
lower flange below the valve is available in 2” or 3”, FNPT or FBSP. If a 3” or 4” threaded connection
is needed for a 150 Series Big Gun®sprinkler, the sprinkler must be specified with a Nelson flange,
and the Nelson Flange x Threaded adapter used.
KEY POINTS
Portable / Solid Set: Design Guidelines
Notes:
1. Not available on SRNV100
2. Includes gaskets and bolts
3. Includes gasket only
4. Available on SR200 and F200HD only; standard F200 use Nelson x ANSI adapter kit #12807
75 SERIES 100 SERIES 150 SERIES 200 SERIES
THREADED
CONNECTION 1.5” FNPT / FBSP
2” FNPT / FBSP 2” FNPT / FBSP
2.5” FNPT1Use FI Adapter
(Nelson Flange x Threaded) Use FI Adapter (Nelson Flange x Threaded)
FLANGE
CONNECTION
2” ANSI/DIN Compatible
Nelson2
Euro3
” ANSI/DIN Compatible
Nelson1, 2
Euro1, 3
3” ANSI/DIN Compatible
Nelson2
Euro2
4” ANSI/DIN Compatible4
Nelson2
Euro2
Table 1. Available connections on Big Gun®sprinklers.
Table 2. Flange adapters for use with Big Gun®sprinklers.
ADAPTER 75 & 100 SERIES 150 SERIES 200 SERIES
Big Gun/Valve Combo
ANSI Flange, Threaded
2” FNPT - #10356
2” FBSP - #12940
3” FNPT - #13233-001
3” FBSP - #13233-002 -
FI Adapter
Nelson x Threaded
2” FNPT - #6860
2” FBSP - #7050
2.5” FNPT - #7040
2.5” FBSP - #7051
3” FNPT - #8403-001
3” FBSP - #8820
3.5” FNPT - #6621-000
3.5” FBSP - #6621-001
4” FNPT - #9127
4” FNPT - #9127
Nelson x ANSI Flange Adapter - - #12807 (F200 Only)
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• Only use the QC100 with 75 and 100 Series Big Gun®sprinklers
• Only use the QC150 with 150 Series Big Gun®sprinklers
• Maximum allowable extension between the QC Key and Big Gun®sprinkler is 12”
The Nelson Quick-Coupling (QC) Valve/Key system is an excellent solution for portable sprinkler
systems. It allows the system to remain pressurized while the sprinklers are moved from position
to position. Remember the following guidelines when using the Nelson QC Valve/Key system:
1.1.2 PORTABLE SYSTEMS WITH THE QC VALVE/KEY
The QC Valve and Key models and connections are summarized in Table 3. The QC100 Key
connects directly to a 75 or 100 Series Big Gun®sprinkler (replaces the flange on the sprinkler); it
is also available with a threaded outlet when an extension is needed between the QC Key and the
sprinkler.
The QC150 Key is only available with 3” Nelson flange outlet, for connecting directly to the 150
Series Big Gun®sprinkler. The QC150 Valve is only available with a 3” threaded inlet.
Portable / Solid Set: Design Guidelines
Table 3. QC Valve and Key models and connections
Figure 2. F100 Big Gun® sprinkler mounted to QC100 valve and key (left), and QC150 valve and key
(right).
QC150 valve
(3” inlet)
QC100 valve
(2” inlet)
QC150 key
QC100 key
F100 Big Gun®
MODEL INLET CONNECTION OUTLET CONNECTION
QC100 Valve 2" FNPT, 3” FNPT, 2” FBSP, 3” FBSP Connects to QC100 Key
QC100 Key Connects to QC100 Valve Direct to 75/100 Series, 2” FNPT, 2” FBSP
QC150 Valve 3” FNPT, 3” FBSP Connects to QC150 Key
QC150 Key Connects to QC150 Valve 3” Nelson Flange
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Portable / Solid Set: Design Guidelines
1.2 TRAJECTORY
• The 24 degree trajectory oers the best balance between wind
resistance and throw distance.
• Trajectory aects stream height, throw distance, droplet patterns,
wind drift and evaporation, and uniformity.
Selection of the correct trajectory angle for the Nelson Big Gun®sprinkler will result in optimization
of pattern uniformity, minimized wind drift and evaporation, maximized radius of throw, and best
droplet conditions possible. Generally, the 24° trajectory angle provides the best balance between
wind resistance and throw distance.
Use the lower trajectory angle models or the variable trajectory models in windy conditions. While
a 27° trajectory will give maximum radius in no wind conditions, the 24° trajectory or 21° trajectory
will perform better in the wind. Note that higher trajectory angles give more desirable droplet
patterns. When using lower trajectory angles use slightly higher operating pressures to enhance
the droplet pattern. Riser height should also be considered when choosing the trajectory angle; tall
risers may allow a lower trajectory.
The trajectory of the sprinkler aects the stream height. For example, the 0.7” taper bore nozzle
at 80 psi on a 24° trajectory 100 Series Big Gun®sprinkler has a peak stream height of 24 feet
above the nozzle. Under the same conditions, the 21° trajectory throws 19 feet above the nozzle.
When choosing sprinkler trajectory and designing the sprinkler layout, beware of overhanging tree
branches and power lines. Additional information about stream trajectory is found in the design
guidelines for industrial and environmental applications, and stream heights are found in the
performance tables in the Big Gun®Technical Manual.
KEY POINTS
T
TRAJECTORIES
THROW DISTANCE
STREAM HEIGHT
180 210 240270 430
Figure 3. Relative eect of trajectory on stream height and throw distance.
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1.3 NOZZLE AND PRESSURE
Portable / Solid Set: Design Guidelines
• The taper bore nozzle is the best choice for most portable and solid set irrigation
applications.
• Always use adequate pressure.
• Use secondary nozzles to improve uniformity.
KEY POINTS
There are three types of Big Gun nozzles: taper bore, taper ring, and ring nozzles. Taper bore gives
the greatest throw distance, while ring nozzles are interchangeable and provide more diusion.
The taper ring nozzle combines the changeability of the ring nozzle with some of the throw
distance eciency of the taper bore. Not all types of nozzles are available on each series of Big
Gun®sprinkler; consult the comparison table on page 5. For most portable and solid set irrigation
applications, the taper bore nozzle is the best choice. However, the ring nozzle will improve stream
breakup when operating pressures are low.
RING
NOZZLE
DIFFUSION DISTANCE
TAPER BORE
NOZZLE
TAPER RING
NOZZLE
Figure 4. From left to right: ring nozzle set, taper ring nozzle set, and taper bore nozzle.
Figure 5. Stream diusion and throw distance varies with nozzle type.
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Portable / Solid Set: Design Guidelines
Always use adequate pressure. To produce good uniformity and desirable droplet characteristics,
Big Gun®sprinklers require higher operating pressures than small sprinklers. Lower operating
pressure does not necessarily reduce operating cost. Lower pressure results in reduced radius of
throw and lower uniformity, which require closer sprinkler spacing, greater labor, and longer run
times to apply the net water requirements. Furthermore, in many designs the actual pressure at
the nozzle ends up being less than expected due to unaccounted pressure losses in the system.
Avoid poor stream break-up and uniformity problems by designing for proper pressure.
For best results, choose nozzle sizes and operating pressure from near the center of the
performance table. For example, the 0.7” taper bore nozzle at 70 psi oers ideal performance for
the 100 Series Big Gun®sprinkler. The 150 Series likewise performs best in the 1.0-1.1” nozzle range,
around 90 psi. Ideal operating pressures for a given flow rate are shown in the Table 4. If less than
ideal pressure is used, consider using ring nozzles to create better stream breakup and improve
uniformity.
1.3.1 SECONDARY NOZZLES
Secondary nozzles should be used to maximize uniformity, especially when sprinklers are spaced
further apart than head-to-head (i.e. when spacing between sprinklers is greater than the sprinkler
throw radius). The secondary nozzle provides additional water close to the sprinkler. However,
beware of poor water quality that may plug small secondary nozzles. In general, the secondary
nozzle should deliver approximately 10% of the primary nozzle flow rate. The typical nozzle to use
for the 100 series Big Gun®sprinkler is the 7/32” 3RN nozzle. The typical nozzle to use for the 150
Series is the 5/16” (3RN for F150; 7RN for SR150).
H - Max Stream Height above nozzle
T - Trajectory
Rh - Distance to Max Stream Height
R - Sprinkler Radius of throw
H
T
RRh
SR100 DISTRIBUTION CURVE
(TO.7” X 7/32 at 60 psi)
Secondary Nozzle
Application Rate
(in/hr)
Radius (ft)
0
0.2
0.4
0.6
15 30 45 60 75 90 105 120 135
FLOW IDEAL PRESSURE
40-100 gpm (9-22 m3/hr) 60-70 psi (4-5 bar)
100-200 gpm (22-45 m3/hr) 70-80 psi (5-5.5 bar)
200-300 gpm (45-68 m3/hr) 80-90 psi (5.5-6 bar)
300-500 gpm (68-113 m3/hr) 90-100 psi (6-7 bar)
>500 gpm (>113 m3/hr) 100-110 psi (7-7.5 bar)
Figure 5. A secondary nozzle increases the
amount of water applied close to the sprinkler.
Table 4. Ideal operating pressure for a given flow range.
Figure 6. Secondary nozzle kit (#9724) for
SR100 and SR150 sprinklers.
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Figure 7. Rectangular (left) vs triangular (right) spacing.
Portable / Solid Set: Design Guidelines
1.4 SPACING AND UNIFORMITY
• Spacing should generally be 50-65% of the sprinkler throw diameter
• Use closer spacing in windy areas
• Triangular layout generally results in better uniformity
• Irrigation application rate should not exceed the soil water intake rate
For the best system performance and highest uniformity use conservative sprinkler spacing.
Perhaps the most common and biggest mistake designers make is spacing sprinklers too far
apart. Spacing should generally be from 50% to 65% of the sprinkler diameter (100 to 130% of the
sprinkler radius), with the tighter spacing recommended in high wind conditions and for crops and
soils requiring the best uniformity. Use secondary nozzles whenever sprinkler spacing is greater
than head-to-head (more than 50% of throw diameter).
When using a rectangular or staggered spacing ensure the tighter dimension is perpendicular to
the prevailing winds to improve coverage, as shown in Figure 7. Stagger the sprinkler for better
distribution in windy conditions. Maximum spacing (65% of sprinkler diameter) should not be used
in both directions (lateral and sprinkler spacing).
In general, a triangular spacing will result in better real-world uniformity and is the best choice
unless farming operations require that the sprinklers be in-line across rows. Theoretical uniformity
calculations from software programs may show rectangular spacing with higher uniformity, but
field experience generally indicates that triangular spacing is better.
Note that uniformity is calculated in an area where there is complete overlap of sprinklers, as
shown by the “overlap area” box in Figure 7. Uniformity for inconsistent spacing, or field edges
without overlap from part-circle sprinklers should be estimated separately. For best uniformity
across the entire field, use part-circle sprinklers at the field edges.
KEY POINTS
EXAMPLE OF RECTANGULAR SPACING EXAMPLE OF TRIANGULAR SPACING
Wind
50% of
Diameter
50% of
Diameter
Overlap
Area
60-65%
of Diameter
60-65%
of Diameter
Wind
Overlap
Area
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Portable / Solid Set: Design Guidelines
.. APPLICATION RATE
The irrigation application rate is how quickly water is applied. It must not be excessive or runo
may occur, which reduces irrigation eciency, causes erosion, and deteriorates water quality. The
soil must be able to intake the water at the rate it is applied. The gross average application rate
(AAR) assumes that all sprinklers will be operated at the same time and is calculated as follows:
This application guide assumes water quality typical of common agricultural water sources. The
most common water quality concern in agricultural irrigation generally involves nozzle plugging.
Big Gun®sprinklers, with their large nozzles, are particularly good for applications where nozzle
plugging is a concern. However, be cognizant of secondary nozzles that may be more prone to
plugging than the primary nozzle.
Industrial and/or wastewater applications will often have poor water quality that can cause
corrosion of sprinkler parts or other problems. Contact the factory for more information on special
sprinkler coatings and accessories for industrial applications.
If the soil has a low water intake (infiltration) rate, the application rate can be reduced by running
only one sprinkler at a time. This results in a reduced application rate of nearly 60% of that found
with the Average Application Rate equation.
Another way to improve irrigation infiltration is to use automation to create an irrigation program
to “cycle and soak.” For example, if one hour of run time is required to deliver the gross application
depth, set the system to run 4 cycles of 15 minutes. The application rate of well-designed,
overlapped Big Gun systems can be in the range of 0.3 to 0.7 in/hr (7.5 to 18 mm/hr).
To estimate the net depth of water applied, multiply the gross average application rate by the run
time, and then by the irrigation eciency to account for losses due to evaporation, etc. These
losses could be 10-25% depending on nozzle size, pressure, climate, soil type, and crop growth
stage.
1. For more information about sprinkler irrigation eciency, see also:
Keller, J. and Bliesner, R.D. 2000. Sprinkle and trickle irrigation. The Blackburn Press, Caldwell, New Jersey.
Brouwer, C., Prins, K., and Heibloem, M. 1989. Irrigation water management: irrigation scheduling. Food and Agriculture
Organization of the United Nations, Training Manual No. 4. Rome.
Howell, T. 2003. Irrigation eciency. United States Department of Agriculture. Encyclopedia of Water Science.
AAR (in/hr) = 96.3 x Nozzle Flow (gpm)
Sprinkler Spacing (ft) x Pipe Spacing (ft)
AAR (mm/hr) = 1000 x Nozzle Flow (m3/hr)
Sprinkler Spacing (m) x Pipe Spacing (m)
1.5 WATER QUALITY
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Portable / Solid Set: Design Guidelines
1.6 OPERATION
• Use automation to improve uniformity
• Wireless control systems are less susceptible to damage
• Balance water application of full- and part-circle sprinklers
Perhaps the biggest challenge with Big Gun®sprinkler systems is operation. Due to the relatively
high application rates of Big Gun®sprinklers, long irrigation run times typical of other irrigation
methods may result in runo or over-irrigation with these systems. This can be avoided and
managed by using an automated control system. Precision irrigation is possible when Big Gun®
sprinklers are paired with Nelson control valves and TWIG®wireless controls. A wireless control
system is preferred over traditional wired systems due to long wire runs required and the resulting
damage from lightning and rodents.
Full-circle or part-circle operation of the sprinkler has a great influence on the application rate. A
sprinkler set to operate in a half-circle arc will double the application rate. Avoid over-irrigation by
running part-circle sprinklers for less irrigation time.
KEY POINTS
Figure 8. TWIG®Wireless Automation with Nelson control valves helps achieve precision irrigation
with Big Gun®sprinklers.
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1.7 ROTATION SPEED
• Adjust the rotation speed to optimize irrigation and sprinkler performance.
All Big Gun®sprinklers are factory water-tested for steady rotation speed. The rotation speed of
new sprinklers will slow down over time as they “break in” and the actual in-field rotation speed
will vary based on the nozzle size, pressure, and riser design. Sprinklers that rotate too fast will
result in poor uniformity and reduced radius. Sprinklers that rotate too slowly may damage bare
soil or could more easily stall as debris builds up on the sprinkler brake, nozzle, or drive spoon/
vane. Tilted or non-vertical risers can have uneven rotation speed resulting in poor uniformity or
stalling; make sure risers are vertical, or use a counterbalance kit to even out the rotation speed
(see Section 1.8.3)
For best results, follow the ideal rotation speed guidelines in Table 5. Rotation speed can be
changed by adjusting the drive vane angle on full-circle models, or the arm weight position on
part-circle models, as shown in Figures 9 and 10, respectively.
KEY POINTS
Portable / Solid Set: Design Guidelines
BIG GUN®SERIES IDEAL ROTATION SPEED
75 Series 60-90 sec
100 Series 60-90 sec
150 Series 90-120 sec
200 Series 180-210 sec
Table 5. Ideal rotation speed
Figure 9. F100 drive vane adjustment bolt viewed
from the bottom of the drive arm, shown with
the vane in the fast position (left), and slow
position (right).
Figure 10. Rotation speed on the SR100
is controlled by adjusting the arm weight
position.
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1.8 RISER DESIGN
Portable / Solid Set: Design Guidelines
• Avoid excessive turbulence and pressure loss in pipe risers
• Risers should be vertical and have adequate stabilization
• Never use PVC
• Install risers at the correct height for the application
• Use air and pressure relief to protect the system from water hammer
• Use isolation valves for maintenance
The sprinkler riser must be properly designed and installed for optimum performance. Poor riser
design can result in premature wear, pipe breakage, reduced throw distance, sprinkler stalling, and
poor uniformity. Fixing these problems can be expensive; it is better to prevent them by following
the recommendations in this guide. The following factors should be considered:
KEY POINTS
• Hydraulics
• Stabilization and Thrust
• Straightness
• Material
• Protection and Height
• Air Relief, Pressure Relief, and Isolation
• Drain-down
1.8.1 HYDRAULICS
Proper riser design allows adequate pressure to be delivered to each sprinkler with minimal
turbulence and therefore pressure loss. Consider using a design program like IRRICAD to layout
looping pipe networks, and analyze system hydraulics to achieve the best possible design. While
pipe purchase and other installation costs are a one-time, fixed capital cost, energy costs and low
pressure problems are ongoing and will endure throughout the life of the system.
The riser pipe size should be at least equal to the size of the connection on the sprinkler, but
in cases where large nozzles are used, the riser may need to be one pipe size larger than the
sprinkler connection size. Big Gun® sprinkler connection sizes and types are shown in Table 1.
Undersized risers will increase the pressure loss and turbulence, which will negatively impact the
sprinkler performance.
One solution for correcting turbulence is to install stream straightener vanes (see Figure 11) in the
riser immediately below the sprinkler. Vanes are available for 2” and 3” schedule 40 pipe and are
listed in Table 6. These vanes can help reduce water swirling as it enters the sprinkler, resulting
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Portable / Solid Set: Design Guidelines
1.8.2 RISER STABILIZATION AND THRUST
A stable riser is required for correct sprinkler operation. With a stable riser, the sprinkler’s drive
arm is able to consistently engage the stream resulting in uniform sprinkler rotation. A stable riser
also dampens out vibration created by the drive arm. If vibration is not dampened, and is allowed
to travel down to the lateral pipe, it could cause fatigue and possible failure of the tee joint. An
unstable riser that does not provide a solid mount for the sprinkler can significantly reduce
stream throw radius.
Wood support posts or concrete are
the most common methods of riser
stabilization (see Section 1.8 for examples).
If support posts are used to stabilize the
riser, beware of settling pipe or HDPE
laterals/submains that can move with
temperature, causing the riser to pull
away from the support post. Always
properly backfill and compact trenches,
and design thrust blocks using proper
engineering practices.
The thrust generated by a Nelson Big
Gun®sprinkler can be substantial.
Formulas for calculating thrust are
found in Figure 12 and should be used
by engineers to design thrust blocks and
riser stabilization.
1.8.3 RISER STRAIGHTNESS
Risers should be installed vertically for optimum throw distance and even sprinkler rotation.
Angled risers can result in uneven rotation speed or stalling. Swing assemblies, or swing joints,
are a useful method for accomplishing this. In addition to allowing the riser to be plumbed
vertical, they protect the buried pipe lateral from damage if the riser is disturbed by machinery or
livestock.
PIPE DIAMETER LENGTH PART NUMBER
2” 6” 6671
3” 9” 6843
Table 6. Riser stream straightener vanes.
Figure 11. Stream straightener
vanes for pipe risers.
Figure 12. Methods for estimating sprinkler thrust
force.
H
T
Horizontal Force (lbs)
A = Sprinkler Trajectory Angle
A
P
T = 2P Q
38
Q = Flow Rate (gpm)
P = Pressure (psi)
Thrust Force (lbs)
H = T cos (A)
in increased throw distance. However, they should not be used
where there is poor water quality due to the increased potential of
plugging.
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Portable / Solid Set: Design Guidelines
3-ELBOW
SWING ASSEMBLY
Nelson QC100 Valve
2” Galvanized Sch. 40 riser
(8” length reccommended for valve-in-box option)
2” Galvanized Sch. 40 Nipple (10” Length)
2” Galvanized sch. 40 Elbow
2” PVC Sch. 80 Nipple
(8” Length, thread both ends)
2” PVC Sch. 40 Pipe
(12” Length)
2” PVC Sch. 40 Elbow
(Thread X Thread)
2” Galvanized
(Sch. 40 Elbow)
2” PVC Male
Thread Adapter
Nelson
QC Valve
8” (20.3 cm)
length, thread
both ends
Elbow,
thread x thread
12” (30.5 cm)
length
Galvanized Elbow
Galvanized Riser, 8” (20.3 cm)
length (recommended)
2-ELBOW
SWING ASSEMBLY
Figure 13. Example of a 2-elbow swing joint assembly used with a Nelson QC Valve.
Figure 14. Example of a 3-elbow swing joint assembly used with a Nelson QC Valve.
The 2-elbow swing assembly (see Figure 13) is the simplest method used to plumb riser
assemblies, and results in the lowest turbulence and friction loss. It is used where height
adjustment is not critical. This plumbing is not recommended for the QC valve in-box installation
options.
The 3-elbow swing assembly (see Figure 14) provides the most flexible installation. If the riser is hit
by machinery, the 3-axis swing allows movement, helping to limit potential damage. This option is
the best choice for the QC valve in-box installation options due to the flexibility it provides in fine-
tuning the riser height. However, the turbulence and subsequent friction loss generated within the
3-elbow assembly is greater than that generated in the 2-elbow swing assembly.
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Portable / Solid Set: Design Guidelines
In most cases, the riser should NOT be installed perpendicular to the field slope unless a vertical
riser on an extreme slope will cause reduced radius and/or erosion on the uphill side of the
sprinkler. If risers are installed perpendicular to field slope, a counterbalance kit should be installed
on the sprinkler whenever slopes exceed 10 degrees (17%). Otherwise, uneven sprinkler rotation will
occur and stalling is possible. The counterbalance kit (Figure 15) provides an even rotation for non-
vertical risers, and available models are shown in Table 7.
MODEL NUMBER BIG GUN®SERIES PART NUMBER
100CBK 75 and 100 Series 8386
150CBK 150 Series 8399
200CBK SR200 Only 9346
Table 7. Available counterbalance kit models.
Figure 15. Counterbalance kit (left), installed on sprinkler (right) for even rotation on tilted risers.
Figure 16. Risers should not be installed perpendicular to field slope. The sprinkler in this photo will
have uneven watering and may stall without the use of a counterbalance kit.
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