Hydraulic atomisers

Figure 8.8 Two mycopesticide use scenarios showing droplet size spectra expressed as diameters (in p,m) with adjacent volume scale (in pi) and estimated particle distributions in droplet size classes, (a) The atomisers for migrant pest control (usually mounted on vehicles) are both shown applying a blank ULV oil formulation (from) Griffiths and Bateman, 1997) (b) hydraulic atomisers, including different settings of a variable cone nozzle, atomising water +0.1% Agral at 300 kPa (see text)...

Although wide drop-size distributions can sometimes be an advantage (Hislop, 1983) the large numbers of small drops produced in hydraulic nozzle sprays can result in spray drift and inadequate targeting (Miller, 1993). Rotary atomisers (Bals, 1975) can reduce the breadth of drop-size distributions and provide a more targeted size distribution. They have not been widely adopted in broad-acre ground crops, because their spray volumes and drop trajectories often cause control difficulties, but they have found some acceptance in orchard sprayers. 

Figure 8.7 Droplet size spectra water +0.1% Agral, atomised by the Herbi rotary atomiser, compared with three hydraulic nozzles. The hydraulic nozzles were scanned diagonally through the centres of the spray fan (as indicated in the centre right diagram)...

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