GREAT PLAINS YP4425A, Operating Manual, Page: 70 / 170

2018-07-30 Table of Contents Index 401-805M
YP4425A Table of Contents Index Adjustments 66
Fertilizer Relief Valve
Refer to Figure 71
When a “Type 2” fertilizer system is installed, a relief
valve
and pressure gauge are mounted at each
ground drive pump. The relief valve protects the
manifold, lines and fittings from excessive pressure. Any
product that dumps over the relief valve will discharge
from the dump line
in relative safety.
To set relief valve:
1. Unlock plastic jam nut from relief valve knob.
2. Unscrew knob clockwise (looking down) until it
loses contact with internal spring.
3. Screw knob counterclockwise two turns.
Start at this setting.
4. Observe manifold gauge and watch for relief valve
dump line discharge while operating in the field.
5. If valve is dumping product and gauge reads under
65 psi, stop tractor and turn knob
clockwise
1
/
4
turn. Continue operating at normal field speed.
Repeat this step as needed until no product is
discharged from relief valve dump line
.
6. If the pressure gauge reads above 65 psi, change to
a larger orifice. Go to step 2 and repeat.
Fertilizer Orifice Plates
Refer to Figure 72
In general, the orifice needs to be small enough to
create at least 15 psi of pressure in the manifold but
large enough to prevent the manifold pressure from
exceeding 65 psi.
The minimum pressure is required to even out the flow of
fertilizer between rows. To reduce orifice plugging and
pump wear, use the largest orifice practical for your
fertilizer application rate. Alternate orifice plates are
listed in the Seed Rate manual.
The best pressure range to maintain is 20-40 psi to
ensure optimum distribution while minimizing leakage.
Built-in check valves at the row units prevent flow below
15 psi.
The Seed Rate Chart book for this planter (manual part
number 401-805B) contains a table of orifice sizes in
gallons per acre.
System Damage/Uneven Application Risks:
Select orifice plates to balance flow. Sizes too small can result
in system rupture. Sizes too large can result in unbalanced
flow. Orifice plates do not set fertilizer rate. Rate is set at the
pump. Plates only create back-pressure to balance flow.
Figure 71
Fertilizer Relief Valve
25164
1
2
3
4
5
6
7
1 2
5
6
7
7
2
5
7
5
Figure 72
Fertilizer Orifice Plate
29984
Agricultural Chemical Hazard:
Wear protective gloves when changing orifice plates.
1
1