ANDREOLI
ENGINEERING
Operator’s Manual
Self-propelled sprayer ATOM
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5.3
SETTING SPRAY PARAMETERS
5.3.1
Parameters
To correctly choose the volume of chemicals to use, the operator must know the rate volume per hectare of
mixture and the following important parameters:
Maximum limit of chemicals concentration used: this value is marked on the chemicals cans
expressed in droplets on cm
2
.
Cover intensity: it is the optimum number of drops on cm
2
and it can be evaluated using sensible
papers put inside the vegetation and spraying just clear water. The sensible papers have a yellow film
on its surface that changes to blue when it gets wet, allowing to estimate the size of the droplets. It is
possible to have the following different cover intensities: 1) not efficient; 2) good; 3) acceptable; 4)
too heavy; 5) washing.
Leaf Area Index (LAI): it is the ratio between the leaf surface and the ground surface.
Pulverisation degree: it is the dimension of the droplets generated by the nozzles.
It is important to know these parameters to perform a good spray.
To cover both sides of the leaf inside the vegetation it is necessary to use small droplets that are able to
change their direction inside the air stream. Small droplets are synonym of low spray rate per hectare and
homogeneous cover of the vegetation.
Too small droplets are not good as they are deeeply affected by wind drift and evaporation.
5.3.2
Droplets dimensions
Small droplets (100-200 μm) can stick to inclined surface much better than bigger ones (400-500 μm) thus
reducing pollution on the ground.
Very small droplets (< 50 μm) can change their direction easily in presence of wind and are more exposed to
drift.
Droplets dimension is reduced by:
wider angle covered by the nozzle ;
smaller nozzles (lower spray rate);
increased pressure.
Using low spray rate is possible to increase the total surface covered with chemicals.
5.3.3
Reducing drift and pollution
Dispersion of chemicals is mainly due to:
dispersion in the atmosphere due to drift or evaporation in case of small droplets (<100 μm);
dispersion on the ground;
non uniform treatment due to improper regulation of nozzles and conveyors;
non uniform treatment due to different concentration of chemical inside the tank while working;
non uniform treatment due to improper speed regulation;
wrong chemical concentration due to errors occurred while preparing the mixture;
washing the machine after the work.
