Abstract: The disclosed apparatus includes a supply line (22) between a source of liquid paint (64) and an applicator (62) having at least two pigs (20A and 20B) and a source of liquid solvent (60) which delivers solvent (60) between the two pigs (20A and 20B) and the pigs (20A and 20B) are driven by paint (80) from adjacent the paint source (64) to the applicator (62). The apparatus further includes a second source of liquid solvent (60) which delivers solvent (60) between the pigs (20A and 20B) adjacent the applicator (62) and the pigs (20A and 20B) are returned through the supply line (22), thereby flushing the supply line (22). In the disclosed embodiment, the source of liquid paint (64) is a piston dosing device (70) which receives paint (80) from a color changer or the like and delivers a predetermined volume of paint (80) to the applicator (62). The delivery line (22) preferably includes a friction resistant inner layer, an intermediate dielectric layer and a protective outer layer.

Abstract: A paint delivery and application system including a color changer, at least two paint canisters and a paint applicator, a first pair of supply lines connected between the color changer and the paint canisters and a second pair of supply lines connecting the paint canisters and the paint applicator, wherein the paint canisters operate in tandem permitting delivery of a first paint to one of the paint canisters while a second paint canister is electrically isolated from the color changer and is delivering paint to the applicator. In one disclosed embodiment, the delivery line from the paint canisters to the applicator includes two pigs and solvent is delivered between the pigs, such that this system is self purging.

Abstract: A spray coating apparatus (10) for applying a paint composed of a controlled mixture of two liquid components. A first gear pump (32) is disposed in a spray booth (30) and pumps the first component to an applicator (14). A second gear pump (36) in the spray booth (30) pumps the second component to the applicator (14). A manifold (44) is disposed between the two gear pumps (32, 36) and the applicator (14) for converging the two paint components. A variable speed motor (16, 20) controls the rate of fluid pumped by each of the gear pumps (32, 36). Each motor (16, 20) includes an encoder (27, 29) sending feedback signals to an adjustor module (24) which computes an instantaneous ratio between the volumetric flow rates of the first and second components and compares this instantaneous ratio with a reference ratio, then adjusts the instantaneous speed of each motor (16, 20) thereby adjusting the ratio between the volumetric flow rates of the first and second components with respect to the reference ratio.

Abstract: In an electrostatic spray coating method liquid coating material is applied to a workpart inside of a spray booth (12). Alternating flows of liquid coating material, liquid solvent and air are conducted through various internal flow passages in a conduit (14) inside the spray booth. An electronic differentiator (24) is positioned adjacent a predetermined location along the conduit (14) and energized from an electrical source disposed outside of the spray booth (12) to differentiate between the dielectric differences of liquid and gas in the internal flow passage for nonintrusively detecting when the head of liquid flow reaches the predetermined location along the internal flow passage. This is accomplished by an electromagnetic field extending into the flow passage and sensing the changes in the electromagnetic field resulting from dielectric differences between liquid and gas in the flow passage.

Abstract: In an electrostatic spray coating apparatus (10), liquid coating material is applied to a workpart inside of a spray booth (12). Alternating flows of liquid coating material, liquid solvent and air are conducted through various internal flow passages in a conduit (14) inside the spray booth. An electronic differentiator (24) is positioned adjacent a predetermined location along the conduit (14) and energized from an electrical source disposed outside of the spray booth (12) to differentiate between liquid and gas in the internal flow passage for nonintrusively detecting when the head of liquid flow reaches the predetermined location along the internal flow passage. This is accomplished by an electromagnetic field extending into the flow passage and sensing the changes in the electromagnetic field resulting from dielectric differences between liquid and gas in the flow passage.