Abstract: An apparatus for dispensing semi-frozen beverages containing water, a flavoring syrup and carbon dioxide in which the water and flavoring syrup are delivered under a pre-set substantially constant pressure through respective water and syrup flow restrictors to a mixed beverage delivery line so that the proportions of the water and syrup in the mixed beverage are controlled by the water and beverage flow restrictors. The apparatus includes mechanism for selectively passing water under the gas pressure in a reverse direction through the syrup flow restrictor to back flush and clean the same. The apparatus also includes mechanism for automatically controlling the flow of mixed beverage to the freezing chamber and the venting of gas from the freezing chamber to maintain the liquid in the chamber at a preselected level and pressure.