## 3 Results and Discussion
The study shows that for a reduced value of measurement time, and thus a decrease in the number of measured drops in successive trials, the spread of the volume median value (difference between maximum and minimum value), respectively, was recorded in the range: (i) AirMix 11003--8.5 \(\upmu\)m, (ii) MMA 11003 EZ--11.2 \(\upmu\)m, (iii) Teejet 11001 VS--1.8 \(\upmu\)m, (iv) MMA 11003 RS--2.2 \(\upmu\)m, and (v) AirMix 11002--6.7 \(\upmu\)m. The variability of the median volume expressed by the coefficient of variation was, respectively, (i) AirMix 11003--0.78%, (ii) MMA 11003 EZ--0.84%, (iii) Teejet 11001 VS--0.4%, (iv) MMA 11003 RS--0.32%, and (v) AirMix 11002--0.61%. The smallest differences in the relative values of the volumetric median were observed for a minimum of 185,000 drops measured in the fluid stream during the test. For nozzles with a predominant spectrum of coarse (C) and medium (M) droplets, i.e., AirMix (11002--0.8 \(\upmu\)m, 11003--1.6 \(\upmu\)m) and MMA (11003 EZ--3 \(\upmu\)m), such a condition was observed in the range from T = 120 s to T = 60 s of the test time. For nozzles with a dominant spectrum of fine droplets (F), i.e., for the MMA sprayer (11003 RS--2.2 \(\upmu\)m) over the full range of measurement times T = (120, 80, 60, 40, 20, 10) s and Teejet sprayer (11001 VS--1.6 \(\upmu\)m) up to a minimum test time of T = 20 s, there was little variation in median volume diameter values over almost the entire range of measurement times. In the graph (Figure 8), the results of the median volume expressed by the coefficient of variation are presented. The results are summarized for a group of test nozzles, obtained in successive measurement cycles for a variable measurement time. For the six volumetric diameters (Dv0.5), depending on the time of the test run, the relative coefficients of the measure of the variations in their distribution (4) were calculated at the measurement points during the PDA test. \[V_{Dv0.5}=\frac{\mathrm{S}}{\overline{\mathrm{X}}} \tag{4}\]  
where S is the sample standard deviation, and \(\overline{\mathrm{X}}\) is the arithmetic mean of the sample. Figure 6: Number of drops as a function of time during the PDA test. The results presented here indicate a relative variation in the median volume diameter of Dv0.5 of less than 10% (Figure 8). For the Teejet 11001 VS nozzle, the range of variation was 0-5.7%, while for the MMat 11003 RS nozzle, 0-5.6% was recorded. The results confirm that the median volume volume is not affected by the presence of a significant change in the median volume volume. Figure 8: Volumetric median variation as a function of measurement time, determined by the droplet diameter distribution test with the PDA analyzer. Figure 7: Values of median volume as a function of measurement time, determined by the droplet diameter distribution test with the PDA analyzer. the slight differences in the median volumetric diameter values presented and discussed above, determined as the average value for the entire fluid stream, almost over the entire range of measurement times. For nozzles with a larger range of diameters in the spectrum, i.e., the AirMix (11002, 11003) and MMA 11003 EZ, and the smaller number of droplets analyzed during the test (Table 1), clear differences were observed in the values of the relative coefficient taken as a measure of variation. Significant variability was noted at measurement points in areas from 150 to 550 mm away from the axis of the liquid stream for the left and right sides. The recorded changes indicate that the cause of this condition is primarily the decreasing number of droplets recorded in the liquid stream, caused by limiting the measurement time T. The reduction in their number at the measuring points as the distance from the axis of the liquid jet increases is also significant. This is a natural condition for flat-fan nozzles.