US Patent 7004407 Uniform metering system for spray applications

A metering system includes a pumping device having one or more cylinders, each cylinder having a piston therein that is moved by an automated drive system to produce uniform or proportional flow to a single spray nozzle or a plurality of nozzles. The cylinders are mounted between a common base and a common metering plate. Movement of the metering plate relative to the base causes the pistons to slide within the cylinders to provide pulse-free fluid pumping. A rinsing cylinder or dual-action cylinder can also be included to provide delivery of a rinsing agent or multiple liquids to one or more of the spray nozzles simultaneously or in sequence.