3.2.1. Cannon-Type Nozzle

D50, D10 and D90 values were significantly affected by the liquid hose position (HP), the LFR and the AS (*p* < 0.001, Figure 6a). In general, an increment in the droplet size can be observed for every indicator (D50, D10 and D90) with the increase of the liquid hose insertion distance to the original one. In this sense, moving the hose out of the spout generated an important increment in the droplet size, as expected by taking into account the air speed decrease found in the present work (Figure 4). This fact was also summarized in Figure 5a, where a clear increase in this parameter was found when increasing distance. As shown in previous works, air speed and liquid flow rate play key roles on droplet size [53,55]. Thus, the first parameter generates a clear decrease on the drop size and the second one behaves the opposite. Regarding D50, nearly every value obtained in the CP was lower than 100 μm (Figure 6a). This contrasts with the case of the XP, where every value was above 200 μm. AP and OP presented intermediate responses. Maximum and minimum D50 mean values were 325 μm (with XP, minimum LFR and minimum AS) and 49 μm (with CP, minimum LFR and maximum AS). In general, increments of D50 values were in the range 30%–94%: between 50% and 75% moving the liquid hose position from CP to AP, between 79% and 94% when the liquid hose was shifted from AP to OP and between 30%–43% when it was further moved to XP.

**Figure 6.** (**a**) D50 (Volume Median Diameter, VMD), (**b**) D10 and (**c**) D90 values (μm) per liquid hose position (HP), liquid flow rate (LFR) and airflow speed (AS) for the cannon-type nozzle. Bars show the mean ±Standard Error. CP, conventional insertion of liquid hose position; AP, alternative position; OP, out position; XP, extreme position.

D10 values for CP resulted below 45 μm whilst the same values for XP were all above 90 μm (Figure 6b). This fact has important practical implications because the use of pneumatic nozzle with the liquid hose in extreme position, allows to generate a very important fraction of the spray relatively safe from drifting, as it will be discussed in the V100 section. The maximum and minimum D10 mean values were 126 μm (in XP combined with minimum LFR and minimum AS) and 17 μm (in CP combined with minimum LFR and maximum AS; Figure 6b). The D10 mean increase from CP to AP ranged, in this case, from 36% to 80%. The increase range between AP and OP was 52% to 89%, whilst the same for OP to XP was 27% to 37%. In this case, the atypical response of D10 decrease with the LFR increase was also found in the OP (Figure 6b).

D90 values comprised a minimum value of 128 μm (in CP combined with minimum LFR and maximum AS) and a maximum of 682 μm (in XP combined with minimum LFR and minimum AS; Figure 6c). The CP resulted, in general, in values below 200 μm, whilst the XP yielded values above 500 μm. The mean D90 increase values were 73% from CP to AP, 101% from AP to OP and 18% from

OP to XP. In the same way as D50 and D10, D90 values showed their highest heterogeneity in XP with relation to the rest of positions.
