STP1183

    Droplet Size Spectra of Dipel™ Sprayed Through Different Atomizers

    Published: Jan 1993


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    Abstract

    Droplet size spectra were measured for water and two aqueous flowable (AF) formulations of Bacillus thuringiensis (“Dipel™ ”) sprayed from nozzles under simulated aerial application conditions using a Malvern 2600c laser particle sizer in a wind tunnel operating at 27, 45 and 58 m/s. Undiluted formulations of Dipel 6AF and a modified Dipel 6AF were evaluated.

    A Teejet 8004 flat fan nozzle and a Micronair AU5000 rotary cage atomizer were tested. The hydraulic nozzle was evaluated at orientations of 45, 90, and 135° to the airflow with a liquid pressure of 276 kPa (40 psi). The rotary atomizer was tested at liquid flow rates of 2000, 4000, and 8000 mL/min and rotation rates of 4400, 6200 and 9500 rpm.

    Spray deposit patterns on Kromekote cards were assessed in field trials using a Cessna AgHusky aircraft fitted with either 8004 nozzles or AU5000 atomizers. The spray liquids were tagged with a tracer dye for subsequent image analysis to determine droplet densities.

    The Volume Median Diameter (Dv0.5) droplet size values for the sprays measured in the wind tunnel ranged from 146 to 404 μm. for the hydraulic nozzle and 34 to 159 μm. with the rotary atomizer. The Dv0.5 values obtained with the hydraulic nozzle increased with lower wind speed and lower nozzle angle relative to the airstream. The Dv0.5 values obtained using the rotary atomizer increased with higher liquid flow rate, lower airstream velocity and lower atomizer rotation rate. The Dv0.5 was always lower for the modified Dipel than for the standard product sprayed under the same conditions. The Dv0.5 produced by water was lower than both Dipel products under given conditions.

    Droplet deposition densities on Kromokote cards were higher for the modified Dipel 6AF than for the standard product when sprayed through either the AU5000 rotary cage atomizer or the 8004 hydraulic nozzles.

    Keywords:

    Bacillus thuringiensis, droplet size spectra, formulation effects, atomizer types, Malvern laser particle size analyzer, deposit pattern


    Author Information:

    Sanderson, R
    Assistant Professor, Research Specialist, Professor and Research Specialist, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM

    Hewitt, AJ
    Assistant Professor, Research Specialist, Professor and Research Specialist, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM

    Huddleston, EW
    Assistant Professor, Research Specialist, Professor and Research Specialist, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM

    Devisetty, BN
    Associate Research Fellow and Technical Products Manager, Abbott Labs., N. Chicago, IL

    Melchoir, GL
    Associate Research Fellow and Technical Products Manager, Abbott Labs., N. Chicago, IL

    Ross, JB
    Assistant Professor, Research Specialist, Professor and Research Specialist, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM


    Paper ID: STP25138S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP25138S


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