A method and system for supplying electrically conductive coating materials to an electrostatic dispenser with a parallel arrangement of subsystems selectably coupled to the dispenser by a four-port system voltage blocking valve, which electrically isolates the subsystems. The subsystems each include first and second piston cylinders that alternatingly receive a selected coating material from a corresponding manifold and supply the coating material to the dispenser by a subsystem voltage blocking valve, which isolates the dispenser from the manifold, when coupled to the dispenser. The first and second piston cylinders of each subsystem also alternatingly receive a solvent from the corresponding manifold and direct the solvent to a waste receptacle by a corresponding subsystem voltage blocking valve when the subsystem is not coupled to the dispenser. The solvent removes previously supplied coating material from the non-selected subsystem and readies the non-selected subsystem for supplying a next selected coating material to the dispenser.

A fluid supply cylinder with improved flusbability, useable for supplying paints to a dispenser in electrostatic coating systems. The fluid supply cylinder having generally a piston reciprocatingly disposed in a chamber of a body member, the piston having a head with a face opposite an end wall of the chamber, a plurality of chamber fluid ports disposed in the end wall of the chamber, and a plurality of fluid conduits between a corresponding one of the plurality of chamber fluid ports and a common outer fluid port, whereby the reciprocating piston draws fluid into the cylinder chamber and supplies fluid from the cylinder chamber through the plurality of chamber fluid ports in the end wall thereof.

A voltage isolating device selectively electrically isolates from each other two points (13 and 15) of an electrically conductive flow medium having different electrical potentials along a flow path. The electrically conductive flow medium is conveyed in the inner space (18') of a freely protruding carrier (17') having at least one discharge opening (29). The carrier (17') moves back and forth between a first isolating position and a second docking position to allow a transfer flow. The discharge opening (29) is closed until the docking position has been reached, wherein the discharge opening is opened, and is closed again when the carrier is moved out of the docking position.

The paint-spraying apparatus exhibits a supply line 7 for coating material, extending from the color changer to the atomizer. Cut-off valves 26, 27 installed in the supply line delimit an insulating section 25 of said supply line, which insulating section is associated with means 28 to 32 for emptying and flushing said insulating section 25. A voltage divider 16 is connected in parallel to said insulating section 25. When colors are changed, the residual coating material present in said voltage divider 16 can be moved into the empty insulating section 25, after which it is forced by means of slugs back through the entire supply line 7 to the color changer 1, and is thus reclaimed.

A coating system comprises a source of electrically non-insulative coating material, a dispenser for dispensing the coating material toward an article to be coated thereby, an electrostatic high potential supply for supplying charge to the coating material, means for coupling the high potential supply across the dispenser and the article, a first reservoir, and a first valve. The first valve has a first housing providing first, second, third, fourth and fifth ports, and a first component movable within the first housing and having a first passageway selectively to connect the first port to the second port to permit the flow of coating material from the first port to the second port. The first port is coupled to the coating material source, the second port to the first reservoir, and the third port to the dispenser. The second port is coupled to the third port to permit the flow of coating material from the first reservoir to the dispenser. A source is provided for an electrically non-conductive fluid. The first housing and the first movable component define between them a second passageway, and the source of electrically non-conductive fluid is coupled to the fourth port to provide a flow of the electrically non-conductive fluid from the source of electrically non-conductive fluid through the second passageway to flush coating material from surfaces of the first housing and first movable component adjacent the second passageway and exit from the fifth port.