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6.4 SUCTION SYSTEM – FAN
The suction system works by means of a fan, which can
create the vacuum inside the metering boxes.
The fan’s suction power is measured using the vacuum gauge
(Fig. 6.28). Depending on the type of seed, it is recommended
to adjust the suction power using the next table:
TYPE OF SEED
SUCTION PRESSURE (cm H
2
O / mbar)
20 30 40 50 60 70 80 90 100
Sunflower
Corn
Baby corn
Sorghum
Cotton
Rape
Beet
Beans
Fabes (Asturian beans)
Broad beans
Tomato
Leek
Green Beans
Chickpeas
Frijoles-Mexican beans
Round green beans
Cauliflower
Soya beans
Carrots
* The values on the suction pressure table are for standard
seed discs and may vary according to the type of seed.
Fig. 6.28
Fig. 6.28
100
cm of water
40
60
20
80
0
V
KEEP THE AIR OUTLETS FREE OF OBSTACLES.
SUBMINISTRATE ENOUGH POWER TO THE
PNEUMATIC SYSTEM UNTIL REACHING THE
MINIMUM SUCTION POWER VALUES SPECIFIED
IN THE TABLE. CHECK THE DEPRESSURE VALUES
AFTER RUNNING THE FIRST 10 METRES.
IF THE PRESSURE LEVEL IS LOWER THAN THE
ONE RECOMMENDED BY THE MANUFACTURER,
THE SEED DISC’S HOLES COULD HAVE
A LACK OF SEEDS. ON THE OTHER HAND, IF THE
PRESSURE IS EXCESSIVE, DOUBLES COULD
EMERGE OR THE DISTANCE BETWEEN SEEDS
COULD BE IRREGULAR.