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7 - Fault Finding
Testing and Fine Tuning
Calibration of the Flow Constant - PPU
At normal use the PPU stamped into the flow housing is used. However, if necessary in special cases it is possible to fine tune
the PPU for the flow transducer.
Calibration of the flow transducer is carried out with clean water but small changes may occur when adding pesticides or
fertiliser. This will effect the final readings. This is typically noted when the volume displayed on the display does not equal
the actual known volume that was sprayed out. The below formula can be used to “fine tune” the flow transducer PPU for
this purpose.
÷
NOTE! The relation is inverse:
• Lower PPU: The volume displayed will increase.
• Higher PPU: The volume displayed will decrease.
For example, the spray tank is filled with 2400 litres of spray-liquid.
When sprayed out, the display showed a total of 2300 litres. (Original PPU stamped into the flow housing = 120.0)
New PPU =
Original PPU x Displayed Volume
Sprayed Volume
New PPU =
120.0 PPU x 2300 Litres
= 115.0
2400 Litres
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