Dimensioning spray systems attached to center pivots. / Metodologia para dimensionamento de um sistema de pulverização acoplável a pivô central.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

Dimensioning methodology was developed to design and operate a spray system attached to a center pivot, for the purpose of applying chemical products as herbicides, fungicides, insecticides and fertilizers. Both a computer program and prototype equipment were developed. During the spray applications, the aerial structure of the center pivot system moved without irrigating, just transporting the spray system around the area. Two spray bars were installed in each pivot span, in order to compensate for different speeds. Intermittent sprays were used to reduce water application rates. Intermittent sprays were achieved by solenoid valves, which were controlled by micro-controlled electronic circuits synchronized with electric motor gears. The methodology developed allowed dimensioning an attached center pivot spray system with high application uniformity. The system could apply a minimum volume of 246L/ha. The medium volumetric and numeric spectrum drop diameters were 126.30 and 98.25µm, respectively. The medium dispersion coefficient was 1.29, allowing us to classify the drop spectrum as uniform. On/off time sequences 0.4/2.5s, 0.5/2.5s, 0.3/3.5s and 0.4/3.5s resulted in coefficients of variation under 15%, acceptable for ground applications. The controls designed for the spray bar height functioned as planned. The computer program developed in conjunction with the physical model allows the use of the methodology for other center pivot designs.

ASSUNTO(S)

center pivot irrigation systems pulverizators pesticides pesticidas irrigação por pivô central puiverizadores

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