# Design and Construction of a Low-Cost Test Bench for Testing Agricultural Spray Nozzles
## 3 Results and Discussion
### Spraying Test Results  
Air temperature and relative humidity during the experiments were 26 \({}^{\circ}\)C and 43%, respectively. The number of droplets detected in each of the analyzed images ranged from about 1700 to about 38,300. Taking into account all the images, the total number of sampled drops ranged from about 37,800 (0.3 MPa) to about 286,500 (1.5 MPa), much higher than the ISO 5682-1 requirements (representative samples composed by at least 2000 droplets).  
Table 1 reports flow rate data for the nozzle under test, and Table 2 summarizes all the measured spray drop parameters in function of working pressures; mean values were computed assuming each Petri dish as an independent sample.  
As expected, all diameters were affected by pressure: An increase in pressure determined a decrease in diameters, meaning a higher degree of drop pulverization. The measurement system was then able to correctly detect the influence of pressure changes. According to the Albuz catalogue, the spray quality of the ATR80 orange hollow cone nozzles at 0.5 MPa and over is classified as \"very fine\", based upon volumetric median diameter (VMD) \(D_{v0.5}\) values lower than 159 \(\upmu\)m, measured with  
\begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{1}{c}{**Measured Values**} & \multicolumn{2}{c}{**From Nozzle Data Sheets**} \\ \hline
**Pressure, MPa** & **Flow Rate, L/min** & **Pressure, MPa** & **Flow Rate, L/min** \\ \hline
0.308 & 0.88 & & \\
0.517 & 0.98 & 0.5 & 0.99 \\
1.036 & 1.37 & 1.0 & 1.39 \\
1.492 & 1.63 & 1.5 & 1.69 \\ \hline \end{tabular}
\end{table}
Table 1: Measured and reference flow rate values for the nozzle under test.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \multicolumn{1}{c}{} & \multicolumn{2}{c}{**0.3 MPa**} & \multicolumn{2}{c}{**0.5 MPa**} & \multicolumn{2}{c}{**1.0 MPa**} & \multicolumn{2}{c}{**1.5 MPa**} \\ \hline
**Parameter** & **Mean** & **Std Dev** & **Mean** & **Std Dev** & **Mean** & **Std Dev** & **Mean** & **Std Dev** \\ \hline \(D_{10}\) (\(\upmu\)m) & 81.7 & 7.1 & 69.7 & 2.4 & 56.6 & 4.9 & 54.6 & 4.4 \\ \(D_{20}\) (\(\upmu\)m) & 98.0 & 6.7 & 83.1 & 2.6 & 69.1 & 4.7 & 66.6 & 4.5 \\ \(D_{20}\) (\(\upmu\)m) & 113.1 & 6.4 & 95.8 & 3.5 & 82.0 & 4.1 & 79.0 & 4.6 \\ \(D_{32}\) (\(\upmu\)m) & 150.6 & 7.4 & 127.5 & 7.6 & 115.4 & 3.2 & 111.1 & 4.7 \\ \(D_{v0.1}\) (\(\upmu\)m) & 97.1 & 10.9 & 79.6 & 4.0 & 69.9 & 3.4 & 66.2 & 4.1 \\ \(D_{v0.5}\) (\(\upmu\)m) & 173.4 & 7.3 & 148.5 & 9.9 & 138.4 & 5.1 & 135.6 & 3.9 \\ \(D_{v0.9}\) (\(\upmu\)m) & 264.4 & 11.0 & 236.5 & 9.0 & 227.3 & 4.4 & 219.0 & 6.2 \\ RSF & 0.97 & 0.08 & 1.06 & 0.06 & 1.14 & 0.04 & 1.13 & 0.03 \\ NMD (\(\upmu\)m) & 68.3 & 10.2 & 61.4 & 5.2 & 45.3 & 6.1 & 44.2 & 5.7 \\ \(V_{100}\) (\(\%\)) & 11.6 & 3.3 & 22.0 & 4.4 & 25.8 & 2.6 & 28.7 & 2.9 \\ \(V_{200}\) (\(\%\)) & 65.8 & 3.3 & 77.7 & 4.0 & 81.3 & 1.4 & 84.0 & 1.8 \\ \hline \end{tabular}
\end{table}
Table 2: Spray drop parameters in function of working pressures.  
Figure 9: Speed profiles of the mobile platform during the tests.  
phase Doppler anemometry (PDA) systems. Therefore, results obtained with the present test bench qualitatively agree with [PERSON]'s information.  
In addition, this measuring system was quite reliable and accurate: In fact, the coefficients of variation (CV) of all diameters (except \(D_{\text{r0.1}}\) at 0.3 MPa and NMD) ranged between 1.9% and 8.6%. In the excluded cases, CVs ranged between 8.5% and 15.0%. As a general result, variability was higher when diameters were lower.