The FBD Expansion Accumulator Tank is a critical pressure-management component for frozen beverage dispensers (slush and frozen cocktail machines). With a 21.5 oz capacity, this tank acts as a buffer to absorb pressure fluctuations in the syrup and carbonated water lines, ensuring a consistent mix and protecting internal valves from "hammering" or sudden surges. Constructed from high-strength, food-safe materials, it is a genuine OEM part designed for long-term reliability in high-volume fountain environments.