Conversion of Droplet Size Distributions From PMS Optical Array Probe to Malvern Laser Diffraction

Teske, Milton E.; Thistle, Harold W.; Hewitt, Andrew; Kirk, I. W.

doi:10.1615/atomizspr.v12.i123.140

Cited by 23 publications

(19 citation statements)

References 4 publications

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“…Similar behavior with regard to the accuracy of the least squares slope and the reconstructed drop size distribution was found when analyzing other droplet data (Teske and Thistle, 2000;Teske et al, 2002b). It may therefore be concluded that the predicted drop size distributions are a weak function of the root-normal slope, and more strongly dependent on D V0.5 , which is highly correlated in these data.…”

Section: Data Correlationsupporting

confidence: 75%

“…The historical FS database contains 40 AU5000 rotary atomizer entries, out of 250, while the SDTF database contains only three AU5000 entries, out of 1294 (the SDTF was more concerned with hydraulic nozzles spraying agricultural pesticides). To extend the usefulness of the PMS data, an analytical approach was developed to convert PMS rotary atomizer data to Malvern-like data (Teske et al, 2002b). However, a revised database of drop size distributions is now necessary, since many of the spray materials tested in the original FS database are no longer sprayed in forestry situations.…”

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confidence: 99%

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Rotary Atomizer Drop Size Distribution Database

Teske¹,

Thistle²,

Hewitt³

et al. 2005

Transactions of the ASAE

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ABSTRACT. Wind tunnel measurements of drop size distributions fromhe drop size distribution of aerially applied spray material atomized by nozzles influences the magnitude of evaporation, spray deposition, drift, and application effectiveness. Droplet size information, in particular the volume fraction in the smaller droplet sizes (which tend to be more prone to drift) and the larger droplet sizes (which fall largely within the application area), is critical to forestry and agricultural applications, where specific levels of spray material in specific droplet size ranges must be deposited to achieve efficacy.In an effort to build a database of typical formulations and aerial application conditions, the USDA Forest Service (FS), and other agencies and companies, conducted wind tunnel tests to determine drop size distributions of pesticides and simulant spray material when applied through hydraulic and rotary atomizers. These studies, from the 1970s to the 1990s, were intended to provide data to determine the effects of application and tank mix variables on the atomization of aerially applied sprays. The factors considered in these studies included the spray pressure, liquid flow rate, air velocity and shear across the atomizer, physical chemistry (viscosity, specific gravity, and surface tension), and atmospheric conditions. The FS database was summarized in Skyler and Barry (1991) and assembled as a library within the FS aerial spray prediction models AGDISP and FSCBG. A preliminary examination of this database produced techniques for collapsing and correlating the data (Teske et al., 1991) and examining possible non-Newtonian effects (Teske and Bilanin, 1994 These data were measured with a Particle Measurement Systems (PMS) optical array probe, with a minimum droplet resolution of 34 mm. Recently, the Spray Drift Task Force (SDTF) developed a large database of spray droplet size information (Hewitt et al., 2002) based on the Malvern laser diffraction analyzer. This technique allowed measurements of droplet diameters down to 4 mm. The SDTF field and subsequent modeling studies (Teske et al., 2002a;Bird et al., 2002) established that knowledge of the droplet spectrum at its smaller droplet sizes is important for drift assessment, and that the Malvern (or similar) instrument range is essential to recover that detail.Droplets in the range of 80 to 120 mm are often desirable for efficacy in forestry applications. To achieve these droplet sizes, some important fraction of sub-80 mm droplets will always be produced below the 34 mm PMS cutoff. The historical FS database contains 40 AU5000 rotary atomizer entries, out of 250, while the SDTF database contains only three AU5000 entries, out of 1294 (the SDTF was more concerned with hydraulic nozzles spraying agricultural pesticides). To extend the usefulness of the PMS data, an analytical approach was developed to convert PMS rotary atomizer data to Malvern-like data (Teske et al., 2002b). However, a revised database of drop size distributions is now necessary, since many...

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Section: Data Correlationsupporting

confidence: 75%

mentioning

confidence: 99%

Rotary Atomizer Drop Size Distribution Database

Teske¹,

Thistle²,

Hewitt³

et al. 2005

Transactions of the ASAE

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“…Due to the development of modern technology such as powerful computers and lasers, quantitative optical non-imaging light scattering spray characterization techniques have been developed for non-intrusive spray characterization: Phase Doppler Particle Analyzers (PDPA) [5,6], laser diffraction analyzers, e.g., Malvern analyzers [7] and optical array probes [8]. Among them, the PDPA has widely been tested and its usefulness for spray characterization recognized.…”

Section: Introductionmentioning

confidence: 99%

Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Minov

Cointault

Vangeyte³

et al. 2016

Sensors

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Accurate spray characterization helps to better understand the pesticide spray application process. The goal of this research was to present the proof of principle of a droplet size and velocity measuring technique for different types of hydraulic spray nozzles using a high speed backlight image acquisition and analysis system. As only part of the drops of an agricultural spray can be in focus at any given moment, an in-focus criterion based on the gray level gradient was proposed to decide whether a given droplet is in focus or not. In a first experiment, differently sized droplets were generated with a piezoelectric generator and studied to establish the relationship between size and in-focus characteristics. In a second experiment, it was demonstrated that droplet sizes and velocities from a real sprayer could be measured reliably in a non-intrusive way using the newly developed image acquisition set-up and image processing. Measured droplet sizes ranged from 24 μm to 543 μm, depending on the nozzle type and size. Droplet velocities ranged from around 0.5 m/s to 12 m/s. The droplet size and velocity results were compared and related well with the results obtained with a Phase Doppler Particle Analyzer (PDPA).

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“…The spatial bias is reduced when testing nozzles in a concurrent airstream of 13 m/sec and with the measurement location located an appropriate distance from the nozzle, as the combination of these two parameters results in homogeneous droplet velocities throughout the spray cloud 4 . Further, the spatial bias is small (5% or less) for aerial nozzle testing due to the high concurrent airspeeds evaluated 7,8 . To determine the optimal test method to reduce the spatial bias with our current low and high speed wind tunnel facilities, the series of reference nozzles used to determine agricultural spray size classifications 9 were evaluated for droplet size using both laser diffraction and imaging methods 10 .…”

Section: Introductionmentioning

confidence: 99%

Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

Fritz

Hoffmann

2016

JoVE

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When making an application of any crop protection material such as an herbicide or pesticide, the applicator uses a variety of skills and information to make an application so that the material reaches the target site (i.e., plant). Information critical in this process is the droplet size that a particular spray nozzle, spray pressure, and spray solution combination generates, as droplet size greatly influences product efficacy and how the spray moves through the environment. Researchers and product manufacturers commonly use laser diffraction equipment to measure the spray droplet size in laboratory wind tunnels. The work presented here describes methods used in making spray droplet size measurements with laser diffraction equipment for both ground and aerial application scenarios that can be used to ensure inter-and intra-laboratory precision while minimizing sampling bias associated with laser diffraction systems. Maintaining critical measurement distances and concurrent airflow throughout the testing process is key to this precision. Real time data quality analysis is also critical to preventing excess variation in the data or extraneous inclusion of erroneous data. Some limitations of this method include atypical spray nozzles, spray solutions or application conditions that result in spray streams that do not fully atomize within the measurement distances discussed. Successful adaption of this method can provide a highly efficient method for evaluation of the performance of agrochemical spray application nozzles under a variety of operational settings. Also discussed are potential experimental design considerations that can be included to enhance functionality of the data collected.

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Conversion of Droplet Size Distributions From PMS Optical Array Probe to Malvern Laser Diffraction

Cited by 23 publications

References 4 publications

Rotary Atomizer Drop Size Distribution Database

Rotary Atomizer Drop Size Distribution Database

Spray Droplet Characterization from a Single Nozzle by High Speed Image Analysis Using an In-Focus Droplet Criterion

Measuring Spray Droplet Size from Agricultural Nozzles Using Laser Diffraction

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