One of the most common operations i

One of the most common operations in the food industry is the moving of liquidsand solids from one location or processing step to another by pumping. There are manykinds of pumps and the choice depends on the character of the food to be moved. Onecommon type is a rotary gear pump. The inner gears rotate, sucking food into the pumphousing and subsequently squeezing food out of the pump housing. For reasons o1mechanical efficiency, with this type of pump, close clearances between the gears andhousing are essential. Although such a pump would be effective for moving liquids andpastes, it would chew up chunk-type foods, reducing them to purees. Actually, pumpssometimes are used to do just this, but, generally, disintegration is a change that can bestbe controlled with specialized equipment other than pumps, and pumps should be chosenprimarily for their pumping efficiency. A single screw pump is best for moving food withlarge pieces without disintegration. Such pumps are also called progressing cavity pumpsand can be selected for large clearances of the cavities between the turming center rotorand the housing. The food is gently propelled from large clearance to large clearance by the screw like action of the turning rotor. Food pieces such as corn kernels, grapes, andeven small shrimp can be pumped without physical damage. In the gear-type pump thesewould be ground up.