An electrostatic pump in an electrostatic sprayer is disclosed which comprises an ion injection electrode means disposed in a liquid conduit for conveying liquid to a sprayhead, downstream of the ion injection electrode is an ion discharge electrode means comprising an earthed ring, a potential difference is provided between the electrodes to provide hydrostatic pressure for conveying liquid in a conduit to the sprayhead.

An air atomizing nozzle assembly for electrostatic spray guns. The nozzle assembly includes a fluid tip through which liquid coating material is emitted, an air cap having openings through which pressurized air passes to atomize the liquid coating material emitted from the nozzle and having a pair of opposed air horns through which pressurized air passes to shape the atomized coating material into a flat fan spray pattern, and a retaining ring for securing the air cap to the gun barrel and fluid tip. An annular diffuser is located within an internal chamber in the nozzle assembly which receives the prezzurized fan-shaping air from a passageway passing through the barrel of the gun, redirects it, and equalizes the flow of the fan-shaping air to the opposed air horns. The present invention is particularly useful in applications having low liquid coating material flow rates on the order of less than about 3 fluid ounces of material per minute.

A method of substantially eliminating corona discharge at the high-value resistor of an electrostatic spray gun comprises the steps of inserting an insulating tube within a bore formed in the gun barrel, positioning a high-value resistor in the insulating tube, filling a portion of the insulating tube with a slug of dielectric material such as grease and then inserting a high voltage cable into the insulating tube so as to force the grease ahead of the cable. The grease encapsulates the resistor and flows into the space between the insulating tube and bore in the gun barrel to eliminate the presence of air around the resistor so as to prevent corona discharge.

A rotary atomizer spray painting device having a nonconductive fixed, axial tube for feeding paint, and having a nonconductive rotor supported for rotation in a nonconductive housing about the tube on air bearings or nonconductive ball bearings, and having turbine drive blades proximate one end thereof, the rotatable rotor supported inside of a nonconductive housing which has a high voltage electrical path therethrough, electrically connected to one or more symmetrically spaced forwardly projecting needle electrodes, the rotatable rotor being fixedly attached to a nonconductive forwardly projecting bell-shaped atomizer, the housing having pressurized air inlets for directing air in driving relationship to the turbine blades.

An improved electrostatic spray gun is disclosed including an electrically conductive metal handle assembly, an electrically insulative barrel assembly, and an electrically insulative nozzle assembly terminating at its forward end in a small diameter discharge orifice through which the coating material is ejected. An ionizing electrode protrudes from the discharge orifice. The flow of material through the barrel and the nozzle assembly is controlled by a trigger actuated needle and seat valve assembly close to the discharge orifice and in axial alignment with an annular fluid flow passageway in the barrel portion of the gun. A high value resistor is disposed in the barrel portion of the gun and a second lower value resistor is disposed inside the needle valve immediately upstream of the ionizing electrode. The elements of the improved electrostatic spray gun cooperate to provide clean and safe operation.