Design and construction of a peristaltic pump

Abstract

The word 'peristaltic' is derived from the Greek word 'peristaltikos' which means to send around. This word is used to describe the rhythmical wave-like contractions and relaxations which occur along a tube thus propelling the contents forward. This propagating system is found in certain hollow organs of the body working under the control of the involuntary nervous system e.g. in the alimentary canal during digestion and in the womb during childbirth. A peristaltic pump is thus a pump which adopts the same principle to propel, i.e. to pump, the fluid or slurry in the system. An elastic tube is locked between a flat circular track and rollers, which are mounted on a rotor concentric with the track. As the rotor rotates, the rollers pass over the tube, flattening it against the track at the point of contact only.. This "flat" moves around the central curve of the track, driving anything in the tube before it. At the same time the restitution of the tube behind each roller creates a powerful suction, drawing in more fluid to be pushed by the following roller. The principle of peristaltic pumping was first exploited commercially in the 1950's and the pump became familiar in Europe and America. Typically the pumphead had three rollers and the pressure track could be moved up and down a ramp to vary the occlusion of the tube. The system was reliable and is still widely used. Peristaltic pumps have been applied to a vast range of uses ranging from pumping the glaze on tiles to pumping the blood in open heart surgeries. Peristaltic pumps have also been adopted in the production of pharmaceutical and cosmetic products. In the food industry peristaltic pumps have been used to pump the flavour on food, to pump beer and spirits [...].