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Under extreme conditions overpressure can
block the seed flow in the hopper. This causes
seed failure.
You should therefore always check the
function of the pneumatic system and
the placement of seed, especially with
high seed quantities and working speeds.
No grains should remain on the surface
of the field.
If grains are blown out, the fan speed needs to
be increased (short-term up to 4000 rpm)
or the working speed must be reduced, until the
injector system works correctly again.
Metering unit with Venturi-type
injector
The metering units in machines with normal hop-
per and Venturi-type injector are equipped with
a V2A-cover with machined recesses.
During operation the injector nozzle is exposed
to vacuum. This V2A-cover adds additional air
to the air flow.
Metering unit with cover for injector nozzle
The adjustment between injector nozzle and
cover works up to a max. possible seed quantity.
Exceeding this quantity results in a dynamic
pressure at the injector nozzle. This may blow
seed out through the perforated plate, which
leads to a strip-like emerging of the seeds.
These grains are visible on the surface of the
field before they are covered by the packer or
the harrow.
