A SYSTEM TO EVALUATE SHEAR EFFECTS ON SPRAY DRIFT RETARDANT PERFORMANCE

A laboratory system was developed to simulate shear on mixtures of wat er and drift retardants due to their recirculation in sprayer tanks. T hree significantly different drift retardants (<AgRH(O)over cap>) DR-2 000, Nalco-Trol and Nalco-Trol II) were evaluated in both a Myers A36 orchard airblast sprayer and the laboratory system. Droplet size distr ibutions of sprayed samples from the sprayer and the laboratory system were measured with an Aerometric Phase/Doppler Particle Analyzer Drop let size distributions of sprayed samples with drift retardants sheare d with the laboratory system had similar trends to those of samples sh eared with the airblast sprayer as the number of recirculations increa sed. When the number of recirculations through the system increased fr om 0 to 11.4, D-V0.5 of sprayed samples of the 0.1% DR-2000 mixture di d not change significantly from the initial value of 587 mu m, but D-V 0.5 of Sprayed samples with 0.0547% Nalco-Trol and the 0.0547% Nalco-T rol II mixtures decreased from 592 to 422 mu m and from 505 to 366 mu m, respectively. Also, the percent spray volume <200 mu m for mixtures with DR-2000 and Nalco-Trol taken after 11.4 recirculations was 72.8 and 34.1% less than that of a water spray. A possible test system for an ASAE standard is presented.