US Navy Entomology Center of Excellence, Jacksonville, FL CUTTING EDGE TECHNIQUES TO MEASURE DROPLET SPECTRUM AND CHEMICAL DEPOSITION OF PESTICIDE SPRAY Muhammad Farooq US Navy Entomology Center of Excellence, Jacksonville, FL

Disclaimer The views expressed in this presentation are those of the author and do not necessarily reflect the official policy or position of the Department of the Navy, Department of Defense, or the U. S. Government.

Spray Application

Intrusive Methods Coated Slides Coated with MgO, teflon, gelatin, petroleum, resins Impressions or stains are measured Droplet size determined indirectly Mainly suitable for laboratory measurements due to handling issues

Intrusive Methods Coated Films Glossy Paper Leaf Surfaces Liquid Media Water Sensitive paper Oil Sensitive paper Coated Films Glossy Paper Leaf Surfaces Liquid Media

Intrusive Methods Cascade Impactors Air sampled Droplets segregated by inertial separation Amount on each stage related to droplet size Air speed increases and droplet size decreases Source:www.envcoglobal.com

Intrusive Methods Fibrous Media Droplets captured on fibers Droplet size measured directly Research on ways to measure droplets on fibers lead to development of Army Insecticide Measurement System then DCIII Source: CAB International, 1993

DCIII Portable Droplet Counter

Enhancement of Analysis Techniques for Intrusive Methods Reading slides Manually using microscope Drop Vision System that scans slide in to computer that measures the droplet sizes

Drop Vision Slide Microscope with digital image processor Droplet Image Analysis software Graphing & Reporting software

Sensitive Paper Reading System Cards Scanned as Bitmap Image analyzed with Stainalysis or with WRK Image Analyzer Droplet size Droplet density Percent coverage of card surface

Reading of Collected Droplets by Photography Source: Aalborg University, Denmark, Website

Non-Intrusive Methods Photographic Measurements Holographic Optical Array Spectrometer Light Scattering Laser Doppler droplet sizing

Photographic Measurements Frozen image by Short duration high intensity light Mercury vapor lamp, electric spark and flash => 1 ms duration Laser pulses => order of ns High speed camera Images read by image analysis programs Two pulses => Droplet size and velocity

Frozen Image

Photomicrography Rathburn & Miserocchi, JEE, Feb. 1967

Laser Imaging Source: www.oxfordlasers.com

Image Analysis for Size and Velocity Source: www.oxfordlasers.com

Frozen Image of fast moving object Source: www.oxfordlasers.com

Interferometric Mie Imaging Fringe pattern produced by out of focus imaging Number of fringes related to droplet size Droplet size and 3-D Velocity Number density Mass Flux Size-Velocity correlation Source: www.LaVision.de

Shadography High Magnification Image for visualization Sizing by image analysis Droplet size, shape and 2-D Velocity Number density, Mass Flux Size-Velocity correlation Source: www.LaVision.de

Particle Image Velocity 6-10 ns image 100 ns time between images Source: www.LaVision.de

Digital Image Correlation Source: www.LaVision.de

Systems Developed Particle Master Spray Master Flow Master Size and Velocity of droplets Spray Master Visualization of spray Flow Master Study of flows Strain master Deformation of flows or materials under stress

Holography The image can be reproduced with laser to measure droplets

Optical Array Spectrometers Principle Number of obscured diodes related to droplet size Source: CAB International, 1993

Light Scattering Methods Light Intensity Technique Forward scattering spectrometer probe (FSSP) Laser Diffraction Technique Malvern droplet sizing system Sympatec droplet sizing system

Light Intensity Technique Source: CAB International, 1993

Laser Diffraction Technique Principle Source: CAB International, 1993

Laser Diffraction Technique Location of droplet in the beam does not effect the size determination Source: www.sympatec.com

Laser Diffraction Technique Use He-Ne class 3, 632.8 nm laser Spatial measurement systems Easy to set-up and align Provide volume distribution of droplet size Data Rate up to 10 kHz Size range Malvern: 0.1 to 2000 mm with two lenses Sympatec: 0.1 to 3500 mm with 8 lenses

Laser Doppler Droplet Sizing Principle Beam splitter Measurement /probe volume Detector 1 Detector 2 Detector 3 Measurement volume

Laser Doppler Droplet Sizing Principle Filtered signal Frequency of the signal related to droplet velocity Phase shift related to droplet size  Doppler Signal

General Features of PDPA The PDPA is a flux sampling instrument (single particle counter) Provides simultaneous measurement of velocity and size of spherical particles Particle size between ca. 0.5 µm and several millimetres Can analyze many spray characteristics. The most important are: Droplet number distribution Droplet volume distribution Droplet velocity distribution Droplet concentration and Liquid Water Content Turbulence intensity Droplet size velocity correlation

Droplet Size-Velocity Correlation

Data Extraction Dia (mm) V (m/s) 0.01 5.46 0.17 8.13 0.44 5.51 0.03 10.17 0.18 7.95 0.46 9.03 0.05 4.26 0.22 8.28 3.68 7.72 0.25 6.79 7.10 0.07 7.97 0.29 6.40 0.47 6.69 0.08 5.44 0.33 1.95 0.48 7.51 0.09 8.46 8.03 0.50 7.42 0.10 6.51 0.35 4.18 3.66 0.12 7.00 0.37 6.94 1.87 8.42 0.38 3.55 1.93 0.13 11.85 0.39 4.19 0.52 8.65 3.60 1.47 0.54 6.18 0.14 5.24 0.41 0.55 2.57 0.16 6.02 0.43 9.41 0.56 3.67

Summary Data

Portable Particle Counters Air contamination studies Air suction system Laser-based or centrifugal impaction Droplet size range: 0.3 – 20.0 µm Flow rate: Up to 100 L/min Solid particles in gases or liquids Looking for one to measure liquid droplets in air

PDI Flight probe Funded by US Navy for cloud and plane icing studies Based on Laser Doppler sizing principle Design being optimized Source: Artium Technologies Inc.

Spray Application

Why Deposition? Fundamental part of sprayer evaluations in agriculture Practices in public health Bio-assays Droplet size characteristics These techniques do not: Approve or disapprove the delivery system Elucidate the shortcomings of the equipment being tested Lead to improvements for meeting the objective

Deposition Measurement Sampling Quantification may include extraction

Samplers Indicating Samplers Plant species for herbicides Sensitive Paper Water sensitive Oil sensitive

Samplers Passive Samplers Cylindrical collectors Paper Mylar Sheet Plant Leaves Cotton squares Filter papers Plastic tapes Cotton ribbons Useful for course high volume agricultural sprays

Samplers Active samplers Air Samplers Rotating samplers Useful for sub-micron particles and ULV space sprays

Air Samplers Air drawn over a filter medium Flow rate known Sampling time recorded Quantity of spray determined analytically. Result: Concentration of spray in air Concentration is a measure of flux

Air Sampler Settings Source: CAB International, 1993

Rotary Samplers Rotorod Sampler

Rotating slide samplers Rotary Samplers Rotating slide samplers Source: John W. Hoch website

Rotary Samplers Rotating ribbon sampler FLB sampler Source: AMCA Vol25 page 476

Quantification of Deposition Water/Oil soluble tracer dyes mixed in tank Samples washed with suitable solvent Concentration of dye in wash solution quantified Dye on sample surface determined AI on sample surface determined using dye:AI ratio in the tank mixture

Collection by Samplers AMCA Vol25 page 521-524

Sampler Collection Efficiency

Questions? DOD Pest Management Equipment Help Desk http://www.afpmb.org/pubs/equipment/equipmentdesk.htm