Spray application, physical

Witkonton and Ercegovich (1972) studied the transformation of chlordimeform in six different fruits following foliar spray application. They found //-chloro-o-formotoluidide was the only major metabolite identified in apples, pears, cherries, plums, strawberries, and peaches. Chemical/Physical. Reacts with acids forming soluble salts (Hartley and Kidd, 1987). 

Organic coatings are commonly evaluated using salt water immersion, salt fog or spray, modified salt exposure tests (e.g., salt fog with added SO2), and various cyclic exposure tests. Humidity exposure and water immersion, and, for many applications, physical resistance tests (adhesion, impact resistance, etc.) are widely used preliminary tests. Standard methods for most of these tests are given in compilations of standard tests such as the Annual Book of ASTM Standards (16). Test methods have been extensively reviewed (e.g., 17-23). 

Physical Parameters Affecting Aircraft Spray Application... 

The several physical parameters affecting aircraft spray applications for (1) deposit In flagged swath,... 

AKESSON AND YATES Physical Parameters of Spray Application 103... 

The nominal spray application rate, as kg active ingredient (a.i.) per hectare, does not define in any way the dose received by a target plant or organism, nor does it represent the actual distribution within the canopy or individual plant. This consideration does not apply to soil applications, but becomes important for weed control and even more so for pest or pathogen control [4,5]. Hence physical application and formulation factors need to be tailored to specific applications [6]. 

The challenges of application techniques are complemented by a consideration of pesticide formulation science. The development of a practical and stable formulation that has the precise chemical and physical properties to enable the delivery of the active ingredient to the site of action is central to this topic. Although the discussion in this book concentrates on the development of products for the application of pesticides to crops via the use of spray application equipment, it recognises that, firstly, the same considerations apply to other areas of application, and that, secondly, formulation science can and does influence the ultimate safety and efficacy of the product. 

There are many excellent manufacturers of equipment for application of hot melt adhesives and coating systems by many different ways in different physical forms. These include high and low pressure applicators, extruders, slot die coaters, roll coaters, pattern coaters, nozzles, wheels, guns, spray applicators, and foam applicators. The following are some of the major manufacturers of these types of equipment. No intent is made to exclude any manufacturer. However, in the interest of space the following are offered for consideration ... 

The full-prepolymer, quasi-prepolymer, and one-shot techniques may appear to be quite similar, but they each have important bearing on equipment requirements and physical properties. The full-prepolymer method, for example, is die process of choice for making high-performance cast elastomers with superb dynamic properties, such as industrial bumpers and bushings. Quasi-prepolymers are used in less demanding applications like shoe soles, adhesives, and spray elastomers. One-shots make up the rest, including most foams and elastomers. 

Protecting a surface from corrosion by coating can be accomplished by a number of well-established processes which include paints, metal plating (with zinc or cadmium), diffusion, thermal spraying, and, more recently, vapor deposition processes. Of these physical vapor deposition (PVD) is used extensively in corrosion protection. Typical applications are ... 

Chemical vapor deposition competes directly with other coating processes which, in many cases, are more suitable for the application under consideration. These competing processes comprise the physical vapor deposition (PVD) processes of evaporation, sputtering, and ion plating, as well as the molten-material process of thermal spray and the liquid-phase process of solgel. A short description of each process follows. For greater detail, the listed references should be consulted. 

Spray drift is defined for this topic by the National Coalition On Drift Minimization (NCODM) as The physical movement of pesticide through the air at the time of pesticide application or soon thereafter from the target site to any non- or off-target site . Secondary drift, defined by NCDOM as vapor drift or subsequent dust and particle movement after the application , is only partially addressed, although most key principles discussed will still also apply to such secondary movements. 

Emphasis is placed on the atomization processes used in spray combustion and spray drying from which many atomization processes have evolved. Advantages and limitations of the atomization systems are discussed along with typical ranges of operation conditions, design characteristics, and actual and potential applications. The physical properties of some normal liquids are listed in Table... 

Droplet collision is a phenomenon inherent in the dense region of a spray. Droplet collisions may lead to local agglomeration that affects the droplet size distribution. There have been considerable efforts in modeling droplet-droplet collisions and coalescence,12291 but the models are still not generally applicable. 1576] Moreover, the calculations in the dense region of a metal spray is much more complicated than in a diesel spray because the physical phenomena and mechanisms in the dense region are not well understood. 

---