Patent ID: 8231310

Claim:
A coating powder feed unit, comprising: a powder pump fitted with at least two alternating powder chambers between a powder intake valve and a powder outlet valve, each of said power chambers having a tubular filter centrally disposed therethrough, an air connection apparatus for alternatingly applying a vacuum or compressed air to either one of the at least two alternating powder chambers, a pump control to switch either one of the two alternating powder chambers between suction and pressure operating modes, wherein the powder intake valve is open and the powder outlet valve is closed and one of the at least two powder chambers communicates through the air connection apparatus with a vacuum conduit whereby the vacuum is able to aspirate coating powder into the powder chamber in a suction operating mode, wherein the powder intake valve is closed and the powder outlet valve is open and one of the powder chambers communicates through the air connection apparatus with a compressed air conduit so that the compressed air is able to expel a dose of coating powder stored in the powder chamber in a pressure operating mode, and wherein said coating powder feed unit includes a pressure tester in fluid communication with each one of the at least two powder chambers continuously, and wherein said pressure tester generates a test signal as a function of measured compressed air pressure in said pressure operating mode.