The paper presents the results of research carried out as part of regular inspections of test station 001-RH of the Faculty of Agrobiotechnical Sciences Osijek in the area of Požega Slavonia County as a pretest to determine the correctness of nozzles and other vital parts of the technical system as part of the project of their replacement by a trading company for the sale of machinery . By removing the mentioned defects and replacing defective parts of the machines, the operators would ensure a reduction in errors during plant protection and increase the quality of protection. one of the objectives of the test must definitely be to point out to the operators possible errors or malfunctions that must be eliminated. Based on the measurement of the flow of the nozzles of the technical systems, it was determined that they achieved the allowed average flow at a pressure of 3 bar. Taking into account the age of the device, the working process and the manufacturer of the machine, out of a total of 34 respondents, eight of them or 23.52 % were confirmed that all the nozzles did not achieve flows within the tabular allowances. Such nozzles were replaced with new ones. Since the obtained values are specific for each technical system and depend primarily on the age and method of exploitation of the machine, we were unable to compare the obtained values. After replacing the worn-out nozzles and adjusting other elements, such sprinklers met the minimum criteria, i.e. the flow rate was within the limits of permissible deviations from the table values of ± 10%. After training the operator and based on the results achieved, the technical systems were issued with a certificate and sticker as proof of correctness for the next 3 years.