Abstract: An electrostatic powder painting gun head in which a needle electrode is provided at a central portion in the proximity of a cylindrical powder ejection port made of insulator, an annular strip electrode is disposed outside of the powder ejection port, also a gas injection port for forming a gas flow layer along the surface of the annular strip electrode is provided, and further there is provided a high voltage power supply for applying a predetermined voltage between the needle electrode and the annular strip electrode.

Abstract: On the downstream side of a large-diameter cylindrical flow path is disposed a small-diameter cylindrical flow path having a smaller inner diameter than the inner diameter of the large-diameter cylindrical flow path contiguously to the large-diameter cylindrical flow path, an annular electrode is disposed at the upstream end of the small-diameter cylindrical flow path, a needle electrode is provided at the center of the annular electrode applying a D.C. high voltage between the electrodes, and upon charging powder contained in a mixed-phase flow through said cylindrical flow paths, a substantial slip velocity is given to the mixed-phase flow adjacent to the surface of the annular electrode.

Abstract: An improved electrostatic spray gun for the deposition of powdered coating material on a workpiece is disclosed. The spray gun includes a housing having a barrel to which a nozzle is attached for directing the powdered material to the workpiece. A charging electrode, which is connected to a high voltage power supply, is mounted on a diffuser assembly which is clamped between the nozzle and the housing, on which the nozzle is threaded. A regulated gas flow supplied through the housing and the diffuser assembly provides a gas shield around the charging electrode to prevent a buildup of the coating material on the electrode. A novel pneumatic safety interlock continuously monitors the pressure of the gas supplied to the diffuser assembly. The interlock turns off the high voltage power supply and a pump for the coating material in response to a drop in such pressure resulting from a loose nozzle.

Abstract: An electrostatic coating nozzle provided with air jet means for preventing fouling of the nozzle electrode and electrode housing.

Abstract: The invention relates to an electrostatic spray gun for the deposition of powdered coating material characterized by an improved deposition efficiency and provided with a multi-stage, trigger operated control that permits spraying at a plurality of conditions that may be preselected by the operator. An axially disposed needle charging electrode is used and an axial air flow passage surrounds the same to reduce any troublesome accumulation of powder on the needle under all spraying conditions.