Peristaltic pump

A peristaltic pump, also commonly known as a roller pump, is a type of positive displacement pump used for pumping a variety of fluids. The fluid is contained in a flexible tube fitted inside a circular pump casing. Most peristaltic pumps work through rotary motion, though linear peristaltic pumps have also been made. The rotor has a number of "wipers" or "rollers" attached to its external circumference, which compress the flexible tube as they rotate by. The part of the tube under compression is closed, forcing the fluid to move through the tube. Additionally, as the tube opens to its natural state after the rollers pass, more fluid is drawn into the tube. This process is called peristalsis and is used in many biological systems such as the gastrointestinal tract. Typically, there will be two or more rollers compressing the tube, trapping a body of fluid between them. The body of fluid is transported through the tube, toward the pump outlet. Peristaltic pumps may run continuously, or they may be indexed through partial revolutions to deliver smaller amounts of fluid.

History

A form of peristaltic pump was described in The Mechanics Magazine in 1845. The pump used a leather hose which did not need to self-open when released by the rollers, instead relying on the incoming water having sufficient pressure to fill the open inlet end on each cycle. The peristaltic pump was first patented in the United States by Rufus Porter and J. D. Bradley in 1855 (U.S. Patent number 12753) as a well pump, and later by Eugene Allen in 1881 (U.S. Patent number 249285) for blood transfusions. It was developed by heart surgeon Dr. Michael DeBakey for blood transfusions while he was a medical student in 1932 and later used by him for cardiopulmonary bypass systems. A simlilar device (Appareil Louis Henry et Dr Pierre Jouvelet) was presented in February 1934 at the Académie de Médecine in France. A specialized nonocclusive roller pump (US Patent 5222880) using soft flat tubing was developed in 1992 for cardiopulmonary bypass systems.

Applications Peristaltic pumps are typically used to pump clean/sterile or highly reactive fluids without exposing those fluids to contamination from exposed pump components. Some common applications include pumping IV fluids through an infusion device, apheresis, highly reactive chemicals, high-solids slurries, and other materials where isolation of the product from the environment are critical. They are also used in heart–lung machines to circulate blood during bypass surgery, and in hemodialysis systems, since the pump does not cause significant hemolysis, or rupture of the blood cells.

Key design parameters The ideal peristaltic pump should have an infinite diameter of the pump head and the largest possible diameter of the rollers. Such an ideal peristaltic pump would offer the longest possible tubing lifetime and provide a constant and pulsation-free flow rate. Such an ideal peristaltic pump cannot be constructed in reality. However, peristaltic pumps can be designed to approach these ideal peristaltic pump parameters. Careful design can offer constant accurate flow rates for several weeks together with a long tubing lifetime without the risk of tubing rupture.

… excerpt ends here. Continue reading the full article.