U.P.B. Sci. Bull., Series D, Vol. 80, Iss. 1, 2018 ISSN 1454-2358 EXPERIMENTAL RESEARCHES REGARDING THE DISPERSION ANGLE OF THE NOZZLE JET FROM SPRAYING MACHINES Mihaela ROŞU (NIŢU) 1 , Tudor CĂSĂNDROIU 2 , Mihai-Gabriel MATACHE 3 , Valentin VLĂDUŢ 4 , Augustina PRUTEANU 5 During the working process achieved by the spraying machines, an important role is that of the nozzles, which transform the spraying liquid substance in a drops jet of different dimensions, in the shape of a cone with a certain angle at the top. The size of this angle plays an important role in the process of covering the spraying surfaces and in placement of nozzles along support lance fitted on the spraying machine. The size of nozzle jet angle depends on the physical properties of the spraying substance, on nozzle geometry and on the functional characteristics of the system. In particular for every substance, angle size depends on the working pressure and nozzle diameter. In the paper are presented experimental results obtained from measurements achieved with three different commonly used commercial substances and six types of nozzles used on current machines. With this data, the mathematical model proposed in a previous work by the authors was tested. Effective mathematical models that have been proposed provide a good prediction of the nozzle jet angle. The estimated values compared to experimental data correspond to a correlation coefficient R=0.91 – 0.97, at a variation coefficient under 5% for major researched cases. Keywords: spraying machine, nozzle, angle jet, phytosanitary treatment 1. Introduction Our health is indissoluble linked to the health of soil and plants providing us food products [1]. The use of pesticides is an integral part of modern agriculture and contributes to the productivity and the quality of the cultivated crop. It has been estimated that the use of agrochemicals prevents a loss of up to 45% of the world food supply. On the other hand, the increasing use of crop protection products is one of the rising environmental concerns [2]. 1 Phd. Student, National Research - Development Institute For Machines And Installations Designed To Agriculture And Food Industry, Bucharest, Romania, rosumihaelan@yahoo.com 2 Prof., Emerit, Dep. of Biotechnical Systems, University POLITEHNICA of Bucharest, Romania, cctu39@yahoo.com 3 Ph.D. eng., National Research - Development Institute For Machines And Installations Designed To Agriculture And Food Industry, Bucharest, Romania, gabimatache@yahoo.com 4 Ph.D. eng., National Research - Development Institute For Machines And Installations Designed To Agriculture And Food Industry, Bucharest, Romania, valentin_vladut@yahoo.com 5 Researcher, National Research - Development Institute For Machines And Installations Designed To Agriculture And Food Industry, Bucharest, Romania, pruteanu_augustina@yahoo.com