Abstract: The disclosed invention relates to electrostatic spraying systems for liquids and specifically to an improved spray-charging nozzle system having increased reliability, consistency, safety and power efficiency for long-term operation in harsh agricultural and industrial applications. The invention achieves these advantages by: a) management of the interaction of any externally-originating electric fields with the droplet-charging electric-induction field being applied within the nozzle, including partial or total exclusion of the former fields; b) maintenance of the charge-induction electric field at the droplet-formation zone by precluding or minimizing leakage of charge in all directions from the induction electrode; c) protection of electronic and nozzle components from damage due to inadvertent overcurrents; and d) facilitation of non-tedious, convenient, trouble-free inspection and cleaning of the nozzle under harsh field conditions.

Abstract: Air atomizing induction charging spray nozzles suited for use with conductive liquids, solutions, suspensions or emulsions. These systems feature a high level of the spray charging at low induction--electrode voltage and current. Primary benefits include consistent, reliable operation in harsh agricultural and industrial environments with a wide range of spray formulations, especially those having relatively high concentrations of abrasive and conductive materials. Internal and external surfaces are configured to minimize potential differences between electrode and ground. Such nozzles may employ external cavities, field concentrators, hoods and other structures and arrangements to affect aerodynamic flow of gases within the vicinity of the nozzles and electrostatic and electrodynamics effects such as those caused by electrical fields within the vicinity of the nozzles.

Abstract: A method for increasing the efficiency of electrostatic deposition of particulate matter on a surface, which comprises preparing a dispersion of electrostatically charged particles of an active material to be deposited on the surface, wherein the particles of active material have an average radius of r.sub.p1 and a total volume of V.sub.L1, in a space adjacent to the surface which contains a dispersion of particles of an inert material, electrostatically charged with the same polarity as said particles of active material, wherein the particles of inert material have an average radius of r.sub.p2 and a total volume of V.sub.L2, wherein r.sub.p1 >r.sub.

Abstract: Disclosed is a low volume, space-charge controlled electrostatic spraying which is particularly suitable for use in agriculture but is applicable to industrial and other settings as well. A substance is sprayed through a relatively low voltage nozzle producing finely divided, electrostatically charged particles of the substance. The charged particles are liquid droplets or dust particles, and are about 50 microns or less in size. The space-charge density of the charged particles is monitored, and the deposition of particles on a calibration target is measured at different space-charge densities to establish an optimal space-charge density corresponding to optimum (e.g., maximum or most uniform) deposition. As the charged particles are subsequently directed to target objects, such as plants, the space-charge density is monitored and the spraying and/or charging systems are controlled to maintain the established optimal level which corresponds to optimal deposition.

Abstract: A system for electrostatic spraying of liquids, such as agricultural pesticides, paints and other liquids, which relies on a novel spray nozzle that combines pneumatic atomization and electrostatic induction charging to provide a stream of electrostatically charged fine droplets. The nozzle uses a low voltage power supply, e.g. a 12 volt battery, electronically raises the voltage to a level in the range of several hundred to several thousand volts, and applies the high voltage to an annular induction electrode which is embedded in the spray nozzle. The high voltage components are inside the nozzle, which is made of an electrically insulating material, to minimize the danger of shock and the possibility of mechanical damage to the high voltage components. The spray nozzle operates at a relatively low voltage and at a low input power, but provides a droplet stream at a high droplet charging level, for effective and uniform deposition of the sprayed liquid onto the target.