Many dispensers exist for dispensing liquids. Some dispensers mix one liquid, such as a juice or syrup, with another, such as water, to form a finished product. Others, such as some cheese dispensers or pharmaceutical dispensers, need not perform such mixing. Whatever the application, it is important that the dispensers perform reliably, that they dispense the correct amount of liquids, and that they are cost effective (among other considerations).
Unfortunately, many problems exist with existing dispensers. For example, in some dispensers, the accuracy of the pumping is low, resulting in poor quality or high costs, or both. Also, in some dispensers, there are high failure rates in the pumping mechanism. Also, the cost of the dispensers or the packaging for the liquid to be dispensed is often too high. Another area of concern is cleanliness; many dispensers are hard to clean. Still other issues arise with the difficulty with which the liquid packaging is loaded into and removed from the dispenser, and the dripping that can occur with such loading and removal. Indeed, attempts to prevent dripping often add unwarranted cost, and can cause system failures where they require a user to remember to move a valve from a closed to an open position after loading of a new package.
Therefore, a need has arisen for methods and apparatus for pumping and dispensing which overcome limitations of prior art systems.