The heart of any peristatic pump is the tubing. It is the primary fluid-contacting part and is occluded by the pump rotor and housing, thus providing the pumping action. With some attention when installing or changing tubing and proper tubing material selection, the pumping system can be optimized.
Proper tube loading can improve the tubing life and overall pumping performance and accuracy. It can also provide consistency between tubing changes by implementing a standardized process for tubing installation.
Match the pump to the tubing size. Peristaltic pumps require specific tubing sizes—determined by the inside diameter (ID), the outside diameter (OD), and the wall thickness—to operate correctly. Using the wrong size in a pump can lead to improper function of the retaining mechanism, no pumping action, and even premature failure of the tubing. Use of precision peristaltic pump tubing in the right size can ensure that the pump system will operate correctly.
Proper tubing selection, which is detailed in the following section, will ensure that the tubing matches the requirements for the fluid system design. When choosing the right tubing for an application, there are many factors to consider. To make the process simple, use the acronym STAMP—size, temperature, application, media, and pressure—to help remember each factor.
Size. The ID, OD, and wall thickness of the tube are significant factors in pressure and vacuum ratings and must be considered in the decision. The tolerances are also a concern for optimal operation in peristaltic pumps. The typical tolerance of off-the-shelf nominal tubing can be greater than +/-5%. If this non-precision tubing is used, it can cause problems with volumetric accuracy, suction lift, or pressure; poor tubing life can also be a result.
Temperature. Operating temperature is most often considered due to its importance, but cleaning temperature, ambient temperature, and the overall temperature fluctuation must also be considered. Sudden changes or extreme temperatures can negatively affect performance and cause premature failures. A higher cost material has traditionally been the only option to improve performance in extreme temperatures. With advances in manufacturing capabilities, however, multilayer products are available that can help ease this cost while still meeting the performance expectations.