Abstract: An electrostatic spraying nozzle, particularly for agricultural use, provides for a high rate of liquid delivery, up to 6 or 7 mL/s, while maintaining uniform charging of the atomized spray by means of a low-current supply. Atomization is produced centrifugally from a conical rotor and the liquid is charged by contact with an electrically isolated conductive coating on the surface of the rotor. The coating is raised to the potential of a high-voltage needle electrode by conduction through one or more air-gaps between the needle point and the conductive surface. The conductive surface is of sufficient extent in relation to the position of the electrode to shield the electrode from any external surface at earth potential and thus to ensure that only the required charging current is passed by the electrode. A shielding action is produced by a relatively deep conical form which also allows a high flow rate. For a frustro-conical surface of apical angle 60.degree. a ratio of end radii in the range 0.85 to 0.

Abstract: An electrostatic crop spraying apparatus is arranged so that spray is ejected from the nozzle directly towards the crop, either vertically downwards or at an angle intermediate between the horizontal and the vertical. With respect to the vertical, the spray liquid is fed to the upper surface of a rotatable disc from which it is centrifugally distributed on to the inner surface of a rotatable hollow cone coaxial with the disc. The truncated apex of the cone is uppermost and the liquid is atomized on ejection from the lower circumferential edge of the cone. Charging of the spray is produced at the surface of the disc or of the cone by means of an electrode which maintains an ionized air path to the surface over a distance of a few mm. The current flow for an electrode potential in the range 15 to 30kV is a few .mu.A. A pump may be used to supply liquid to the nozzle in a pulsed flow.