Retaining rings cure fastener concerns in medical application 07 January 2019

Peristaltic pumps are used to move fluids along a tube in a variety of medical and industrial applications. They can pump sterile or harsh fluids without coming into contact with other components of the pump that can contaminate clean fluids or be damaged by acidic or viscous fluids.

The core of the pump in this design is a series of rollers that are fastened to a wheel. A tube containing the fluid comes in contact with the rollers as they turn. The rollers pinch the tube in order to force the contents in the tube to move along.

As the tube returns to its natural ‘unpinched’ state, between each roller, the force causes additional fluid to move through the passageway, thus keeping a steady flow through the pump. This is often referred to as a form of positive displacement pumping.

This process is called peristalsis and is used in many biological systems, most famously in the gastrointestinal tract. Common applications for peristaltic pumps include heart-lung machines to circulate blood during bypass surgery, and in hemodialysis systems.

Designers were concerned about the extra costs associated with retaining eight separate rollers on their own shaft using traditional fasteners, like screws, nuts and bolts. Limited space was also a consideration along with the costs associated with assembling so many small components.

The E Retaining Ring from Rotorclip was the fastener of choice, offering the designers the following advantages:

• Less shaft preparation (no threading, tapping or drilling).
• Reduced weight and size of finished designs.
• Lower costs of raw material and labour in assembly of components.

Claire Aldridge Deputy Editor t: +44 (0) 1727 814 450

Having joined the magazine in 2012, Claire developed her knowledge of the industry through the numerous company visits, exhibitions and conferences she attended both in the UK and abroad.

Claire prides herself on keeping readers well informed and up to date with the latest industry news.