## 2 Materials and Methods  
The subjects of the study were new flat-fan nozzles: injector nozzles, ejector nozzles, standard nozzles, and nozzles with a higher pressure range. The nozzles tested were randomly selected from a group of ten for each nozzle type. The tests were carried out for nozzles with the following catalog names and parameters: 11001 VS (TeeJet, Wheaton, IL, USA) with nozzle size 01 (orange), droplet size distribution in the range of 144-235 \(\upmu\)m F (fine), and operating pressure in the range of 1-3 bar; 11002 AirMix (Agrotop GmbH, Obertraubling, Germany) with nozzle size 02 (yellow), a droplet size distribution in the range of 250-350 \(\upmu\)m M (medium), and operating pressure in the range of 2-4 bar; 11003 AirMix (Agrotop GmbH, Obertraubling, Germany) with nozzle size 03 (blue), droplet size distribution in the range of 350-400 \(\upmu\)m C (coarse), and an operating pressure in the range of 2-4 bar; RS11003 (Agro Technology MMAT, Leszno, Poland) with nozzle size 03, droplet size distribution in the range of 144-235 \(\upmu\)m F (fine), and an operating pressure in the range of 3-4 bar; and EZ11003 (Agro Technology MMAT, Leszno, Poland) with nozzle size 03, droplet size distribution in the range of 350-400 \(\upmu\)m C (coarse), and an operating pressure of 3-3.5 bar. The spray liquid was demineralized water with a temperature in the range of 19 to 20 \({}^{\circ}\)C. All tests were carried out over seven working days in a controlled laboratory environment with a temperature of 20 \(\pm\) 2 \({}^{\circ}\)C and room relative humidity between 40 and 80%. The maintenance of the same laboratory conditions resulting from the intervals between tests was verified by conducting additional measurements for the nozzles tested earlier. Deviations between individual results for the same types of nozzles did not exceed \(\pm\)5%. Before the start of the main tests, the discharge rate of the liquid from each nozzle was measured to verify the correctness of their output. Individual tests showed that the maximum deviation did not exceed \(\pm\)3% from the values in the catalog data. The study began by determining the variation of coefficients characterizing the spray spectrum in the form of average volume diameters Dv0.1, Dv0.5, and Dv0.9; relative span factor (RSF); arithmetic mean diameter (D10); volume diameter (D30); and percentage of total volume of droplets smaller than 100 \(\upmu\)m (V100). All coefficients were tested as a function of variable measurement time. Then, based on the volumetric diameter of D30, the value of the coefficient of variation of the liquid distribution CV (for a single sprayer) was determined. In the final stage of the study, a composite of individual test results was performed to obtain the CV coefficient of variation for the spray boom section. The correctness of the obtained test results (CV coefficient for a single sprayer and for a virtual boom) was verified on a groove table. A diagram of the use of the two measurement methods is shown in the assembly (Figure 1). The study of the distribution of the spray spectrum as a function of a variable measurement time value was carried out using a 2D LDA/PDA laser droplet analyzer from Dantec Dynamics (Skovlunde, Denmark) (Figure 2) applying the following parameters (Table 1). A study of the distribution of the spray spectrum for the individual nozzles was carried out along the y-measurement axis (Figure 3). The receiving probe in relation to the laser beam is located at an angle of 43.5\({}^{\circ}\), which ensures the dominance of the light scattering mode refraction. In their work, [PERSON] et al. write that PDPA measurements are not based upon the scattered light intensity and, consequently, are not subject to errors from beam attenuation or deflection which occur in dense particle environments [38]. The intersecting laser beams create a measurement space (v) for the moving liquid particles.