Disclosed herein is a structure for preventing current from leaking out of devices such as a valve, an intermediate reservoir, etc., which are employed in an electrostatic spray coating apparatus for applying a desired voltage to electrically conductive paint so as to electrostatically spray-coat a workpiece therewith. The current-leakage prevention structure basically comprises any one of the devices each made of an electrically-conductive material, a container made of an insulating material, which accommodates the device therein and has a paint passage defined therein capable of communicating with the device, and a cover for externally covering the container. A creepage distance defined by the container and the cover is set to reach a desired creepage length or more capable of preventing current leakage. It is therefore possible to reliably prevent current from leaking even when a high voltage is applied to the devices.
A coating-powder spray gun includes a gun housing (2) of which the front end face is sealed pressure-hermetically with respect to compressed gas by a front end wall (28). A current-limiting resistor (32) and at least a portion of a high-voltage generator (10) are potted in an integral electrically insulating block. The potted block may be received in the gun housing (2).
An electrically isolating pressure feed paint reservoir suitable for holding electrically conductive paint applied with an electrostatic spray gun. A paint container is located in an electrically insulated housing which is mounted on a dolly for portability. The housing also mounts a pneumatically operated paint pump for delivering pressurized paint to the spray gun. When a lid to the housing is removed the high voltage power source is turned off and any high voltage present in the housing is discharged through a resistor.
An electrostatic device for spraying electrically conductive liquid coating product comprises a storage tank for the product in which the product is at a high voltage. The tank is defined in a substantially cylindrical cavity formed in an insulative material body and inside in which is a piston forming in the cavity a mobile wall separating a coating product chamber from an actuation chamber filled with an electrically insulative actuation fluid. The body is fixed to a conductive material socket which is grounded and to which is connected an actuation fluid supply circuit extending between the socket and the actuation chamber and discharging into the actuation chamber near a back wall of the cavity which is not in contact with the coating product. A section of the supply circuit runs substantially parallel to the cavity in the direction away from the socket starting from the back wall.
A liquid pumping system for transporting conductive liquids to an electrostatic spraying device while maintaining electrical isolation between the spraying device and the liquid source; the system includes sequentially-arranged metering valves and pumps to sequentially transport predetermined and isolated quantities of liquid.
