Abstract: A liquid dispenser includes a metering chamber with a piston assembly movable therein for variance of the chamber volume and a supply chamber capable of liquid communication with the metering chamber. A hollow valve body with valve seats communicating with the metering and supply chambers and with a dispensing outlet is positioned between such chambers. A valve member is located within the valve body and is actuable by a control mechanism such that it is given an operating cycle whereby during one operating cycle the valve member is actuated into a first position to close the valve seat communicating with the supply chamber and to permit communication between the metering chamber and dispensing outlet and is maintained in the first position for a period of time sufficient to permit the emptying of the metering chamber through the dispensing outlet.

Abstract: A liquid dispenser having a metering chamber and a supply chamber disposed in side by side relationship and adapted for liquid communication with one another through a normally open supply valve. The liquid in the chambers are maintained at the same level. An outlet drain from the metering chamber through which liquid may be drained from the metering chamber and a normally closed outlet valve for controlling the flow of liquid through the outlet drain is provided. The supply valve and said outlet valve co-operate in such manner that upon opening the outlet valve to dispense liquid from the metering chamber, the supply valve closes and then subsequently re-opens for replenishing the metering chamber from the supply chamber only after the outlet valve has closed.