Great Plains 1625AHL Operator Manual - Manual (Page 57)

Great Plains Manufacturing, Inc. Table of Contents Index Operating Instructions 53
2014-04-21 Table of Contents Index 411-020M
Fan General Operating Information
Dry fertilizer metering rate is set by the variable rate gear
box; however, the fan must be set to provide sufficient
manifold pressure to deliver the metered material from
the airbox to the rows.
Starting Fan
Use tractor remote hydraulic valve flow control to set fan
speed. Always start the fan with a low flow setting.
Monitor fan output with the Magnehelic
®
pressure gauge.
Gradually bring fan up to the pressure recommended for
your rate. Normal readings are in the 35 inches to
45 inches of water (H
2
O) range with the system
operating (material flowing). Pressure needed varies with
material properties and application rate.
At excessive rpm, too much air flow can cause:
• oil heating
• slow lift times
• fan motor damage, over 9000 rpm
If desired pressure cannot be reached, chances are the
fan is running backwards. Check the inlet/return lines at
the hitch.
If air system does not operate suitably at suggested
pressures, see “Dry Fertilizer Delivery
Troubleshooting” on page 96.
Stopping Fan
Move circuit level to Neutral, or slowly reduce rate to
zero.
Butterfly Valve Operation (all valves):
To adjust, loosen bolt
and rotate the handle .
Re-tighten bolt.
0
° is open - maximum air flow.
90
° is closed - no air flow.
The valve provides the most effect at settings between
20
° and 70°.
Equipment Damage Risk:
Make only gradual changes to fan hydraulic flow (other than
shifting to Neutral). Fan impeller inertia and momentum can
cause pressure spikes in the motor in response to abrupt
changes. This can cause motor seal damage.
Do not operate fan above 9000 rpm.
Note: Fan pressure readings are lower when no dry
fertilizer is flowing. It may not be possible to reach
40 psi without material flow.
Note: Fan speed is likely to require adjustment when
afield. Back-pressure from the material workload:
• increases pressure
• reduces CFM
• increases fan speed (due to cavitation).
Note: Higher material rates require higher pressure.
Maximum application rates (approaching
400kg/ha) typically require 40 psi or more.
90
60
30
0
848-020C
Figure 41
Fan Butterfly Valve Open
25137
1
2
20
°
45
°
70
°
1 2