Select and install orifice plates, Determine orifice size – Great Plains NP3000A Operator Manual User Manual
Page 95
Great Plains Manufacturing, Inc.
Fertilizer Rates
91
2014-04-22
407-613M
Select and Install Orifice Plates
If using VeriFlow nozzles, orifice plate instructions do not
apply. However, the topic “Tramlines and Doubled
Rows” on page 92 applies to all types of nozzles.
Agricultural Chemical Hazard:
Wear protective gloves when changing orifice plates. Consult
material manufacturer or supplier documents for proper
handling and steps to take if skin contact occurs.
Refer to Figure 58
Orifice plates
at each drop line nozzle provide
back-pressure that balances flow in the manifolds,
assuring that each row obtains the same flow rate. For a
given rate, there may be more than one orifice size that
provides the recommended back-pressure.
Plates are provided with the system in three sizes.
Additional sizes are available. In general, the orifice
needs to be small enough to create a minimum pressure
in the manifold but large enough to prevent the manifold
pressure from exceeding the maximum:
15 psi min., 15-40 psi optimal, 65 psi max.
Using an orifice size too large can result in unequal flow
at rows. Using a size too small can cause excess
back-pressure resulting in material dumping at the relief
valve.
Determine Orifice Size
The chart below shows rate ranges for each Great Plains
orifice size and row spacing. You may need to change to
the next higher or lower orifice for a different fertilizer
solution density and/or a different ground speed.
To reduce orifice plugging and pump wear, use the
largest orifice practical for your fertilizer application rate.
Material Loss or Misapplication Risks:
Orifice size must be appropriate for rate selected. Drop line
orifice plates do not affect rate on ground drive pumps, and
are not used to control rate on hydraulic drive pumps. If the
orifice size is too small, over-pressure in system may result in
material loss at the ground drive relief valve. A size too small
for a hydraulic drive system may require excess pressure to
achieve the target rate. An orifice size too large may result in
uneven application across all rows.
If changing rate, changing material, changing field speed or
shutting off rows, review orifice sizing.
Figure 58
Fertilizer Drop Line Nozzle
29984
L38
L38
Orifice Plate Size
20
28*
34*
48*
59
80
98
Recommended Rate Range in Gallons per Acre. Range is 15 - 40 PSI
Nozzle Spacing
(Values based on: 5.0 mph, 10.7 lbs/gallon Fertilizer solution density)
10 inch (30in triple)
3.4 - 5.5
6.3 - 10
9.5 - 15
18 - 30
28 - 46
51 - 83
80 - 131
15 inch (30in twin)
2.2 - 3.6
4.2 - 6.9
6.3 - 10
12 - 20
19 - 30
34 - 56
54 - 88
30 inch single
1.1 - 1.8
2.1 - 3.4
3.2 - 5.2
6.1 - 10
9.3 - 15
17 - 28
27 - 44
* These sizes standard in most Great Plains fertilizer systems.
31014N