The invention relates to a valve assembly for use in connection with
carpet cleaning extraction machines and similar extraction cleaning
devices. The invention allows the intake of liquid and the mixing of
different liquids in a mixing chamber, such as clean water with
detergent, and the discharge of a selected liquid without the formation
of an air or vapor lock that would inhibit the discharge of the selected
liquid. In particular, the invention prevents the formation of a vapor
lock when water is being drawn into a chamber that would prevent the
subsequent discharge or spraying of the liquid.