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Influence of Nozzle Type and Spray Pressure on Droplet Size

This study examines the impact of different nozzle types and spray pressures on droplet size in order to optimize spray quality and minimize drift. The findings suggest that while extended range tips perform well in terms of efficacy, other nozzles have significantly lower drift potential in certain conditions.

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Influence of Nozzle Type and Spray Pressure on Droplet Size

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  1. Influence of Nozzle Type and Spray Pressure on Droplet Size Robert Wolf Biological and Agricultural Engineering Dept. Cathy Minihan and Dallas Peterson Department of Agronomy

  2. Nozzles Types? • Nozzles designed to reduce drift • Improved ‘Droplet Spectrum’ • Emphasis on ‘Spray Quality’ How should each be used????

  3. New Label language-EPA ‘PR Notice’ Out Match the crop protection product to the target Adhere to label guidelines based on an industry standard ASAE S-572 Buffer Zones or No Spray Zones Maximize Efficacy Minimize Drift EPA Requested Changes Coming!!!! VMD

  4. EPA Pesticide Registration Notice: • PR Notice issued in the Federal Register on August 22, 2001 • Pages 44141-44143 • www.epa.gov/fedrgstr/ • Click on date – look for document • 90-day public comment period • Original date - Nov. 20, 2001 • Extended until Jan. 19, 2002

  5. Objective of this study: Field measure the spray droplet characteristics of venturi flat-fan nozzles at 345 kPa (50 PSI) compared to extended range flat-fan nozzles at 173 kPa (25 PSI), and turbo flat-fan and DR flat-fan nozzles at 242 kPa (35 PSI).

  6. Materials and Methods: Experiments: Exp. 1 and 2 - Early and Late Postemergence Grass Location: Ashland Bottoms, Manhattan, KS Exp. Design: 2 x 2 x 4 split-split plot with 4 reps Drop Collectors: Placed in 2 reps with 3 cards per rep (192 cards) Plot Size: 3 x 9 m with 1.5 m buffer Crop Oats ‘Don’ Visual Ratings: 1, 2, and 4 weeks after treatment Herbicides (2): Paraquat, 878 ml/ha, NIS @ .25% Glyphosate, 878 ml/ha Application Conditions: Exp. 1Exp. 2 Date: April 25, 2001 May 2, 2001 Oat Size: 15 cm 51 cm Temperature: 26 C 23 C R. H.: 20% 65% Wind: S-SW@ 4-5 km/h SE 3-6 km/h

  7. Materials and Methods cont.: Spray Tips (4): Extended Range Flat-fan (XR) Turbo Flat-fan (TT) Combo-Jet DR Air Induction Flat-fan (AI) Spray Volumes (2): 47 L/ha (110015 orifice tips) 94 L/ha (110025 orifice tips) 94 L/ha (11003 orifice tips) Application Ground Speed: 7.6 – 8.8 km/h Spray Pressure: 173, 242, 345 kPa Spray Tip Spacing: 76 cm Canopy Boom Height: 51 cm

  8. DropletScan used to analyze droplets: Water Sensitive Paper Software & lock-key Color Scanner Portable computer Color Printer System Components

  9. What is DropletScan ? • A software program that will allow accurate and rapid measure of spray droplet impressions on water-sensitive paper. • Developed at K-State by Devore Systems - modeled after ‘Crumbscan’, a software program to determine hole sizes in slices of bread.

  10. Important Droplet Statistics: • Dv0.1 (µm) - 10% of the spray volume in drops < number reported • Dv0.5 (µm) - 50% of the spray volume in drops < number reported (also is VMD- volume median diameter) • Dv0.9 (µm) - 90% of the spray volume in drops < number reported • Number of droplets under 200 microns

  11. Important Droplet Statistics: VMD (50%) Operational Area VD0.9 (90%) VD0.1 (10%)

  12. Collection Procedure:

  13. Results and Discussion

  14. Sample cards: XR TT DR AI XR TT DR AI 47 L/ha 94 L/ha

  15. Spray Droplet Size – Tip * Volume 47 L/ha XR TT DR AI 94 L/ha

  16. Drift Potential – Tip * Volume 47 L/ha XR TT DR AI 94 L/ha

  17. Efficacy – Tip * Volume 47 L/ha XR TT DR AI LSD=2 94 L/ha

  18. Summary of findings Dv0.5 (µm) (VMD): • As the spray volume increased the Dv0.5 (µm) (VMD) also increased. • The venturi flat-fan tips produced the largest droplets (VMD) with the Combo-Jet next smallest in size. The turbo flat-fans produced the next smallest droplets and the extended range flat-fan tips produced the smallest droplets. • This trend was present for both application volumes.

  19. Summary of Findings – Drift Potential: • At 47 L/ha the extended range flat-fan produced approximately 70% more droplets under 200 microns than the turbo flat-fan, 580% more than the Combo-Jet and 960% more than the venturi flat-fan. • At 94 L/ha the extended range flat-fan produced approximately 100% more droplets under 200 microns than the turbo flat-fan, 400% more than the Combo-Jet and 450% more than the venturi flat-fan.

  20. Summary of findings for the Efficacy: • At 47 L/ha efficacy data collected indicates that the extended range flat-fan tips slightly out performed the turbo flat-fan tips which slightly out performed the Combo-jet tips, which slightly outperformed the venturi flat-fan tips. • At 94 L/ha a similar trend was shown with each nozzle while overall performance for each nozzle was less than at 47 L/ha.

  21. Take Away Message: Even though the extended range tips slightly outperformed the other nozzles for oat control, these other nozzles had significantly less drift potential and should be considered when conditions for drift are present.

  22. Thanks

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