Spray Adjuvant Effects on Droplet Size Spectra Measured by Three Laser-Based Systems in a High-Speed Wind Tunnel PDF Download
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Author: J. B. Ross Publisher: ISBN: Category : Adjuvants Languages : en Pages : 12
Book Description
Spray droplet size has long been recognized as the most important variable that aerial applicators can influence to mitigate spray drift from the application site. There are several different technologies that are used by researchers to measure droplet size from spray nozzles. The objective of these studies was to determine the influence of eight spray adjuvants on the droplet size spectrum produced by two nozzles in a high-speed wind tunnel when characterized using three different droplet size measurement systems. The adjuvant, nozzles, and airspeeds used in these studies are commonly used by aerial applicators. Three droplet sizing systems (Malvern laser diffraction, PMS optical array probe, and LaVision laser imaging) were simultaneously operated to measure the spray droplet size spectra for each adjuvant, airspeed, and nozzle combination. Two spray nozzles (a D6-46 nozzle and a D2 straight stream nozzle) were evaluated in a high-speed wind tunnel at airspeeds of 45 and 58 m/sec. There were significant differences in the droplet size spectra produced by the eight spray adjuvants tested. There were also significant differences between the droplet size values reported by the three measurement systems (Malvern, LaVision, and PMS) evaluated; however, there was considerable agreement trendwise. In general, the Malvern reported smaller spray droplet size spectra values than the LaVision, while the PMS system generally reported the largest spray droplet size spectra values. These tests are the first reported studies where all three droplet sizing systems were operated simultaneously.
Author: J. B. Ross Publisher: ISBN: Category : Adjuvants Languages : en Pages : 12
Book Description
Spray droplet size has long been recognized as the most important variable that aerial applicators can influence to mitigate spray drift from the application site. There are several different technologies that are used by researchers to measure droplet size from spray nozzles. The objective of these studies was to determine the influence of eight spray adjuvants on the droplet size spectrum produced by two nozzles in a high-speed wind tunnel when characterized using three different droplet size measurement systems. The adjuvant, nozzles, and airspeeds used in these studies are commonly used by aerial applicators. Three droplet sizing systems (Malvern laser diffraction, PMS optical array probe, and LaVision laser imaging) were simultaneously operated to measure the spray droplet size spectra for each adjuvant, airspeed, and nozzle combination. Two spray nozzles (a D6-46 nozzle and a D2 straight stream nozzle) were evaluated in a high-speed wind tunnel at airspeeds of 45 and 58 m/sec. There were significant differences in the droplet size spectra produced by the eight spray adjuvants tested. There were also significant differences between the droplet size values reported by the three measurement systems (Malvern, LaVision, and PMS) evaluated; however, there was considerable agreement trendwise. In general, the Malvern reported smaller spray droplet size spectra values than the LaVision, while the PMS system generally reported the largest spray droplet size spectra values. These tests are the first reported studies where all three droplet sizing systems were operated simultaneously.
Author: WR. Dexter Publisher: ISBN: Category : Adjuvants Languages : en Pages : 12
Book Description
The literature on the effects of active ingredients, adjuvants and surface active agents on the droplet size of agricultural sprays is reviewed. The effects of various agricultural adjuvants on the droplet size distributions of a herbicide sprayed in a wind tunnel simulating an aerial application were determined using a Malvern laser diffraction instrument. All adjuvants caused a decrease in droplet size, which varied with adjuvant type and concentration. Measurements of equilibrium surface tension, dynamic surface tension at 20 ms, density, and viscosity were recorded. Droplet size did not correlate linearly with equilibrium surface tension: only at the lowest surface tensions was any significant decrease in droplet size observed. Droplet size correlated better with dynamic surface tension for each adjuvant over most of the surface tension range, but with different slopes for each adjuvant. At high concentrations of surfactant, bubbles of air were observed within captured droplets and the size distribution became bimodal.
Author: Robert E. Wolf Publisher: ISBN: Category : Active ingredient Languages : en Pages : 18
Book Description
The impact of tank mix adjuvants and a formulated fungicide on spray atomization and in-field movement under aerial application conditions was examined. High speed wind tunnel testing was conducted to determine droplet size resulting from treatments selected for evaluation in the field. These treatments included a "blank" (water plus a non-ionic surfactant) as well as five additional solutions with a formulated fungicide, four of which have an additional adjuvant. The wind tunnel testing measured droplet size using the flat fan nozzles and operational parameters (spray pressure, nozzle orientation, and airspeed) selected for field trials. These treatments were then evaluated in the field for both in-swath and downwind deposition, with a mass balance on the measured results used to compare each of the formulated product treatments to a reference treatment. Wind tunnel results showed the formulated product tank mixes resulted in significantly different droplet sizes than the water and non-ionic surfactant "blank" reference sprays. Additional adjuvants resulted in minimal changes in droplet size as compared to the formulated product mixture. However the polymer tested broadened the droplet size distribution. Drift modeling of the wind tunnel droplet size results demonstrated little difference between the formulated product and spray adjuvant spray mixtures. However, all treatment solutions significantly reduced modeled drift as compared to the reference treatment. While the field study results did highlight significant differences between treatments solutions, it also showed a great degree in data variability as a result of meteorological and sampling issues. These results have led the authors to conclude that field testing of potential drift reduction technologies under aerial application conditions will be cost prohibitive and likely would give highly variable results. Wind tunnel evaluations at certified laboratories offer a much quicker and inexpensive method for evaluating large numbers of nozzle and spray formulation treatments.
Author: Chenghai Yang Publisher: ISBN: Category : Droplet size Languages : en Pages : 9
Book Description
Rotary atomizers are used in a number of aerial applications, such as forest pest spraying and mosquito control sprays. These types of atomizers have a rotating cage at speeds of 2,000 to 10,000 revolutions per minute (rpm) through which a spray is emitted and atomized. Many applicators routinely add spray adjuvants to change the droplet size, reduce drift potential, or to reduce evaporative effects of a particular spray solution; therefore, six commonly used classes of spray adjuvants were evaluated to determine their effects on droplet size. If an applicator's only concern was minimizing spray drift, the applicator could choose a polymer or high surfactant oil concentrate for helicopter speeds and a polymer for fixed-wing applications. For applicators working under hot, dry conditions where evaporation is a concern, choosing an oil-based adjuvant to help get better coverage by creating smaller droplets that do not evaporate would be recommended. Understanding the role the different adjuvant types play in the final droplet size of the spray is key to successfully setting up and making applications with rotary atomizers.
Author: Curtis M. Elsik Publisher: ISBN: Category : Acculturation Languages : en Pages : 28
Book Description
Twelve commercial drift reduction agents were evaluated for their characteristics in the three most commonly accepted parameters for spray droplet size formation--extensional viscosity, dynamic surface tension, and kinematic viscosity. Samples were sprayed in both water and in the presence of a commercial herbicide formulation. The spray droplet spectra for these agents were then determined under rigorous control, in still-air conditions, using a Sympatec HELOS/KF laser diffraction particle size analyzer. Spraying an actual pesticide formulation that contains a wetting agent is important because the surfactant present reduces dynamic surface tension and can significantly reduce spray droplet diameter. The aerosol particle size distributions were measured using an electronic actuator that moved the nozzle spray pattern through the laser in a reproducible manner. There are multiple mechanisms that can influence both volume mean diameter and percent fines below 105 microns. There are natural and synthetic water-soluble polymers that function by increasing extensional viscosity. There are oil products that produce emulsions that keep small spray drops from forming. The droplet spectra for the different commercial products were grouped according to their specific drift reduction mechanism in order to see if a better correlation could be made on how they individually affected the resulting droplet particle size distribution.
Author: Kelli L. Nelms Publisher: ISBN: Category : Adjuvant Languages : en Pages : 11
Book Description
Many factors, including adjuvants, pesticide formulations, and nozzle tips, affect spray droplet size. It is important to understand these factors as spray droplet size affects both drift and efficacy of pesticides, which is a main concern with pesticide application. A laser particle analyzer was used to determine the spray droplet size and distributions of a range of formulations sprayed through several types of nozzle tips. Nozzles included were extended range flat fan sizes 11003 and 11005 (Spraying Systems XR), air induction flat fan sizes 11005 and 11004 (AI), air induction extended range flat fan size 11005 (AIXR), preorifice flat fan size 11005 (TT), and a second preorifice flat fan size 2.5 (TF). Several deposition/retention adjuvants were studied, including Array, Interlock, In-Place, and Thrust. Another study looked at diflufenzopyr + dicamba (Status, BASF) in combination with several adjuvants. Also, three fungicides were evaluated at differing spray volumes. Results indicated that the droplet size of some nozzle tips is more affected than others by changes in the contents of the spray solution.
Author: Guilherme Sousa Alves Publisher: ISBN: Category : Nozzles Languages : en Pages : 14
Book Description
Spray classification based on droplet size has been used worldwide to characterize nozzles in relation to efficacy and drift potential. The objectives of this study were to evaluate the effect of pressure, flat angle of nozzle, and deflection angle on droplet spectrum in aerial applications of glyphosate using a high-speed wind tunnel. Two independent studies were conducted: one evaluating pressure (207, 310, 414 kPa) and deflection angle (0, 30, 60, 90) with CP-11TT 8008 nozzles, and another study evaluating flat-fan angle (20, 40, 80) of CP-11TT nozzles with 08 orifice size and the same deflection angles used in a previous study, at 207 kPa pressure. The solution was prepared with water and Roundup PowerMax at 2.34 L ha -1 as a source of glyphosate, simulating a carrier volume of 30 L ha -1 . Droplet size data were recorded in a high-speed wind tunnel using a Sympatec HELOS laser diffraction system. The droplet size was affected by interactions between pressure versus deflection angle and flat-fan versus deflection angle. Selecting narrower angles of flat-fan nozzles and deflections, as well as higher pressures, are viable alternatives to mitigate glyphosate drift from aerial applications.
Author: Kevin Penfield Publisher: ISBN: Category : Adjuvant Languages : en Pages : 12
Book Description
Drifting of fine droplets during the application of pesticides is an issue of increasing commercial and regulatory importance. Spray drift damages susceptible crops, wastes resources, and results in inconsistent weed control. Several strategies are currently used to mitigate this problem. These include enhanced nozzle technology, improved application techniques, and inclusion of drift control additives in the final tank mix. Elimination of small diameter droplets ("driftable fines") is a key goal. Measurements were made of droplet size distributions of sprayed pesticide formulations containing commercial products representative of the leading drift control technologies, including guar, polyacrylamides, lecithin, and oil/surfactant mixtures. Effects of spray nozzle and pressure were also evaluated. Nozzle technology plays a large role in determining the spray droplet size spectrum. However, there is a strong interplay between nozzle design and formulation variables. We found that drift control agents have greater impact on spray from flat fan nozzles. Also, the ranking of adjuvants depends on the nozzle technology in use: for glyphosate/ammonium sulfate solutions, polymers were more effective in reducing fines from a flat fan nozzle, while surfactant-based products were marginally superior when an air induction nozzle was used. The regulatory community is currently focused on mitigating the generation of small droplets. However, the generation of oversized droplets also effects spray efficacy. The impact of drift control agents on the breadth of the droplet size spectrum is an aspect of drift control which is often overlooked. We found that emulsion-based products tighten the droplet size distribution, while the polymer-based products shift the mean droplet diameter up, broadening the distribution in the process: while the latter effect may earn better ratings from regulatory agencies concerned exclusively with spray drift mitigation, it may be less helpful in enhancing application efficacy.
Author: H. Zhu Publisher: ISBN: Category : Droplet size Languages : en Pages : 9
Book Description
Although considerable research has been done on effectiveness of drift retardants for many years, answers to some questions are still unclear to applicators. Laboratory tests were conducted to evaluate drift potentials associated with off-target ground and airborne spray deposits discharged with a hollow cone nozzle spraying three different drift retardants at a high operating pressure and various wind velocities in a wind tunnel. Droplet sizes and spray widths were also determined with a laser imaging system and a portable spray patternator. At 1655 kPa pressure and 4.65 L/m flow rate, the volume median diameters of droplets from the hollow cone nozzle discharging spray mixtures containing water only, polyvinyl polymer, nonionic colloidal polymer and polyacrylamide polymer drift retardants were 201, 222, 239, and 210 μm, respectively. The major spray pattern width was not changed after drift retardants were added into the spray carrier. For the wind velocity from 1 to 5 m/s in the wind tunnel, the polyacrylamide drift retardant produced the highest airborne deposit among the three drift retardants, followed by polyvinyl, and then nonionic colloidal. Also, the polyacrylamide drift retardant produced the highest ground drift potential, followed by nonionic colloidal and then polyvinyl. According to the results from this laboratory study, both nonionic colloidal and polyvinyl polymer drift retardants reduced the drift potential compared to the spray carrier containing water only.
Author: CR. Tuck Publisher: ISBN: Category : Application Languages : en Pages : 13
Book Description
The need for designers and users of pesticide application equipment to balance the risk of off-target contamination with high product efficacies when using the minimum dose of active ingredient has led to the requirement for more data defining the performance of such equipment. Measurements of the droplet size distribution in sprays from conventional nozzles has shown acceptable levels of consistency between data obtained with different measuring systems enabling such sprays to be classified providing that systems are calibrated with agreed reference nozzles. For sprays with air inclusions different measuring systems have been shown to give comparable and consistent results, and there is now a need to fully integrate such sprays into a revised classification scheme. Temperature of both spray liquid and the surrounding air have been shown to influence droplet size distribution measurements. It is therefore proposed that measurement protocols specify a maximum difference in temperature between the spray liquid and surrounding air of 5°C. For boom sprayers it is not possible to predict accurately the risk of drift from droplet size measurements alone because of the complex detrainment mechanisms involved. It is proposed that standardized wind tunnel procedures be defined that enable the relative risk of drift from different nozzle designs to be quantified. In the future it is likely that more of the information relating to application system performance will be delivered pre-programmed in the units control system or as part of a decision support system.
Author: J. B. Ross
Author: J. B. Ross
Author: WR. Dexter
Author: Robert E. Wolf
Author: Chenghai Yang
Author: Curtis M. Elsik
Author: Kelli L. Nelms
Author: Guilherme Sousa Alves
Author: Kevin Penfield
Author: H. Zhu
Author: CR. Tuck