Abstract: An apparatus for metering, mixing, dispensing, testing and purging liquid compositions composed of predetermined ratios of reactive liquid components. Pressurized sources of the component liquids are coupled to valve mechanisms and liquid metering devices. The materials are metered in predetermined ratio to each other and fed to a mixer to be intimately combined and dispensed at a demand station for the intended use. A valve mechanism is provided immediately following the pressurized source of one of the liquids and upon operation of the valve this liquid is diverted around the valve and metering device and is fed directly into the first area in which the two liquids are co-mingled, thereby purging the entire area in which the co-mingled liquids exist. Upon operation of the purging valve, the entire operation of the valves and metering devices are stopped thereby significantly reducing the wear and tear on this portion of this apparatus.