Advances in Spray Nozzle Designs for Chemical Application 851096
Two factors contribute significantly to the widespread acceptance of a new technology in chemical application 1) simplicity 2) field ruggedness. In the past few years several new types of spray nozzles have been developed to meet the changing needs of applicators. Each is designed to meet specific performance criteria and thus has varying degrees of complexity.
The wide angle full cone spray tip and the extended range flat spray tip are both well suited for uses with sprayer controllers. Each hydraulic spray tip has a wide range of operating pressures. The wide angle full cone tip produces large droplets in a full cone pattern. It is well suited for applications where drift control is essential. The nozzle maintains a 120° spray angle throughout a pressure range of 15 to 40 psi.
The extended range flat spray tip provides excellent spray distribution at both low and high pressures unlike conventional flat spray tips. This allows the operator to tailor his droplet size for his specific application. At lower pressures, systemic herbicides can be applied as larger droplets to minimize drift. At higher pressures, droplet size is decreased and velocity -increased for a thorough, penetrating coverage with contact herbicides.
The third new type of hydraulic spray tip is the twin flat spray. This is designed for post-emergence herbicide applications requiring good penetration and coverage. This spray tip produces smaller droplets than equal size flat spray tips by atomizing the liquid through two orifices. Each forms a flat spray pattern, one directed 30° forward, the other directed 30° to the rear, for better penetration.
Renewed interest in applications using lower carrier volumes has been sparked by the introduction of rotary atomizers. These devices use centrifugal rather than hydraulic energy to form droplets. Advantages include a narrow droplet size range, minimal clogging, and the ability to easily change droplet size. However, acceptance has been limited by mechanical problems, cost and performance limitations.
Air-assisted nozzles have also been developed for low volume applications. These represent a compromise between hydraulic and rotary nozzles. No moving parts, lower cost, versatility and field ruggedness are advantages over rotary atomizers but droplet size control is not as precise.