Patent ID: 7331483

Claim:
A method of dispensing a post-mix beverage from a beverage dispenser, comprising the steps of providing a container of beverage concentrate connected to a disposable pump unit that includes a twin barrel piston pump, including a first barrel having a first inlet thereto, a first outlet therefrom and a first piston reciprocable therein and a second barrel having a second inlet thereto, a second outlet therefrom and a second piston reciprocable therein; fluid coupling the first and second barrel inlets to the container of beverage concentrate via at least one inlet valve; using a non-disposable drive system to reciprocate the first piston in the first barrel in one direction in a fill cycle to draw the beverage concentrate into the first barrel from the container via the first inlet and the at least one inlet valve and then in an opposite direction in an emptying cycle to eject the beverage concentrate from the first barrel via the first outlet and to reciprocate the second piston in the second barrel in one direction in a fill cycle to draw the beverage concentrate into the second barrel from the container via the second inlet and the at least one inlet valve and then in an opposite direction in an emptying cycle to eject the beverage concentrate from the second barrel via the second outlet; operating the drive system to reciprocate the first and second pistons such that at least one of the first and second pistons is always moving in the direction in the first and/or second barrel to eject the beverage concentrate from the first and/or second barrel to provide a substantially constant and uninterrupted output flow of the beverage concentrate from the twin barrel piston pump during a dispense cycle; introducing a flow of chilled diluent to the output flow of the beverage concentrate ejected from the twin barrel piston pump; controlling at least one of the drive system for the twin barrel piston pump and the flow of the diluent introduced to the output flow of the beverage concentrate to achieve a predetermined ratiometric mixture of the diluent to the beverage concentrate; passing the mixture of the diluent and beverage concentrate through a mixer to provide a substantially homogeneous mixture of the the diluent and of the beverage concentrate for dispensing from the dispenser into a receptacle; and upon exhaustion of the beverage concentrate in the container, replacing the container with a fresh container of the beverage concentrate, wherein said step of operating the drive system reciprocates the first and second pistons such the emptying cycles of the pistons overlap to provide a substantially continuous output flow of the beverage concentrate from the first and second barrels.