Passive drawback valve for condiment dispensing

A condiment drawback valve comprising:

• a condiment inlet;
• a condiment outlet;
• a condiment channel between the condiment inlet and the condiment outlet;
• a drawback chamber coupled with the condiment channel;
• a movable member movable to change the he drawback chamber;
• a resilient member disposed in the drawback chamber and being coupled with the movable member, the resilient member resiliently biasing the movable member with a biasing force to a rest position providing a maximum volume of the drawback chamber;
• and
• a gas chamber separated from the drawback chamber by the movable member for applying a variable pressure on the movable member against the biasing force of the resilient member.

A method of dispensing condiment at a dispensing outlet from a condiment source using a gas-driven pump and drawing back the condiment from the dispensing outlet during termination of condiment dispensing, the method comprising:

• providing a drawback valve including a condiment channel fluidicly coupled between the pump and the dispensing outlet, the drawback valve having a drawback chamber fluidicly coupled with the condiment channel;
• supplying a flow of gas to compress and reduce the volume of the drawback chamber substantially simultaneously with activation of the pump by a flow of gas to pump the condiment from the condiment source through the condiment channel to the dispensing outlet;
• and
• terminating the flow of gas to increase the volume of the drawback chamber substantially simultaneously with deactivation of the pump by stopping the flow of gas to terminate condiment flow from the condiment source through the condiment channel to the dispensing outlets,
• wherein the drawback valve includes a movable member separating the drawback chamber from a gas chamber and being resiliently biased by a spring disposed in the drawback chamber to a rest position, wherein supplying a flow of gas comprises supplying the flow of gas to the gas chamber to move the movable member from the rest position to reduce the volume of the drawback chamber.