Venturi-type injector
In the Venturi-type injector the metering unit in-
jects the seed or the fertiliser into the air flow.
The SW 3500 S is equipped with a foldable lid at
the bottom, the SW 7000 S with a flexible cover.
For the purpose of calibrating the Venturi area
is opened and the calibration bag is hooked on
to the hooks on the housing.
In order to avoid malfunctions on the injector
nozzle or on the seed transport and its distribu-
tion during the seed placement, all connections
and the lid must be tightly closed.
Air leaks lead to metering errors.
Metering unit with Venturi-type injector on SW 3500 S
Metering unit with Venturi area on SW 7000 S
Hopper
On the SW 3500 S the hopper is an "open hop-
per", whereas on the SW 7000 S it is a "pres-
surized hopper".
Hopper SW 3500 S
The tarpaulin should always be kept closed to
protect the seed against contamination, dust
and moisture.
In case of extreme development of dust, this dust
can deposit in the hopper and fill up the roller
flutes. This causes metering faults and unneces-
sary wear inside the metering unit.
Hopper SW 7000 S
The pressurized hopper enables a higher place-
ment quantity. It must be permanently kept
closed and sealed to avoid malfunctions.
Air losses in the pneumatic system will
reduce the placement quantity. It may
even drop to zero.
Whenever the hopper lid has been opened it
should be checked for air leaks with the fan
running, by listening and feeling with the hands
along the seal.
