STP1078

    Droplet Spectra for Some Agricultural Fan Nozzles, with Respect to Drift and Biological Efficiency

    Published: Jan 1990


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    Abstract

    The differences in drop size characteristics along the long axis of “fine”, “medium” and “coarse” sprays produced by agricultural fan nozzles were determined using the Aerometries Phase Doppler Particle Analyzer (PDPA). Water, water + 0.06% adjuvant, water + 0.4% emulsifiable concentrate (EC) and water +0.2% dispersible granule (DG) were sprayed through each nozzle. There was little difference in volume median diameter (Dv.5), number median diameter (Dn.5) or percent (by number and volume of the spray contained in drops <100um or >300um diameter when water was compared with the DG. However, the EC had a significantly larger Dv.5 than the water sprayed through five out of the six nozzles tested. Therefore, sprays produced by specific nozzles cannot be reliably defined on the basis of data for water alone. The percentage of spray volume contained in drops <100um diameter (most likely to drift) was 4 times greater in fine compared to coarse sprays. However, the 6-fold difference in flowrate results in the higher throughput nozzles producing most “driftable” volume per unit time. In coarse sprays, 69 — 84% by volume, but only 13 – 29% by number, was contained in drops >300um diameter (may rebound upon impaction). When these drops were artificially removed from the analysis, the Dv.5 was in the range 190 – 231um, irrespective of nozzle or'formulation. Thus, while coarse sprays contain, characteristically, large drops (which may contribute to off-target contamination because they are not retained well by plant surfaces), they are not associated with a reduced drift potential compared to fine sprays, based on volume production of drops <100um diameter.

    Keywords:

    Agricultural sprays, drift, drop size, formulation, laser, nozzles, phase doppler particle analyzer


    Author Information:

    Adams, AJ
    post-doctoral research associategraduate research associateHead of the Laboratory for Pest Control Application Technology (LPCAT), Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH

    Chappie, AC
    post-doctoral research associategraduate research associateHead of the Laboratory for Pest Control Application Technology (LPCAT), Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH

    Hall, FR
    post-doctoral research associategraduate research associateHead of the Laboratory for Pest Control Application Technology (LPCAT), Ohio Agricultural Research and Development Center, Ohio State University, Wooster, OH


    Paper ID: STP25379S

    Committee/Subcommittee: E35.22

    DOI: 10.1520/STP25379S


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