Liquid metering and dispensing apparatus

Abstract

Apparatus for spraying plants with liquid treatment chemical such as an insecticide, fungicide, herbicide or the like, includes a reusable container having inlet and outlet hose connections, and a disposable cartridge which is inserted into the container. The cartridge comprises a pressure-sensitive container in the form of a piston cylinder or a collapsible bag containing the liquid chemical, and is mounted within a rigid casing or jar communicating with a stream of water under pressure entering the inlet hose connection. The water also flows through an axial bore in the head of the reusable container to the outlet hose connection, passing from a high pressure side through a mixing chamber to a low pressure side. The pressure sensitive container has a precisely-dimensioned outlet aperture communicating with the mixing chamber in such a manner that liquid chemical is forced under pressure from the pressure-sensitive container of the cartridge and mixes with the flow of water in a precise pre-selected micro-dispensing ratio. The axial bore in the head of the reusable container is configured as a cavitating venturi, producing a low pressure area surrounding a high velocity central liquid core. This low pressure area provides a common outlet pressure for both the stream of water and the liquid chemical, which also have the same upstream head pressures, so that the ratio of flow between the two streams remains constant regardless of the pressure of the water supplied to the apparatus.