Submitted to: Journal of Agricultural Engineering Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 21, 1999
Publication Date: N/A
Interpretive Summary: The first step in effective pest control is applying spray uniformly over a crop. A basic requirement for uniform application is keeping the spray mixture uniform throughout the spray process - from full to empty sprayer tank. Dry formulations of pesticides tend to float or sink to the bottom of the tank and require constant agitation to keep the spray mixture uniform. Hydraulic mixing, where some of the liquid is re-circulated from the pump back into the tank through an agitation nozzle, is the most common method of agitation used in commercial sprayers. This paper presents results from the most comprehensive experimental study ever made of hydraulic agitation systems in agriculture sprayer tanks. Several agitation systems were tested and their effectiveness in producing a uniform tank mixture for the entire sprayer-emptying process was measured. The location and arrangement of the agitation nozzles had a significant effect on the mixing process. By placing small-orifice nozzles along a central manifold good values of mixing effectiveness could be obtained with less than half the mixture bypass volume required to obtain effective mixing with some commercial nozzle arrangements. These data will be extremely useful for sprayer manufacturers who desire the best agitation system for their sprayers, with the minimum power of the sprayer system devoted to the mixing process.
Technical Abstract: Effectiveness of hydraulic jet agitation systems of agrochemical sprayers was investigated by measuring the concentration of a kaolin clay/water mixture in the line to the boom. Experiments were conducted on several sprayer tanks of different capacities and agitator types. An initial series of tests identified the most important parameters effecting the efficiency of a particular agitation system. An experimental design was chosen to determine the effect of each parameter as well as interactions among them. An agitation index, AGEF, was used to evaluate the effectiveness of each agitation system separately regardless of tank size and shape. Statistical analysis of AGEF values showed that system pressure was the most important factor affecting agitation effectiveness through its direct influence on jet velocity. If jet velocity was kept constant, then the volume of fluid delivered into the tank was the most important factor in enhancing mixture uniformity