8
Technical Details
8.1 Theory of Operation
A peristaltic pump is a fluid pump which operates to create a moving region of compression along a flexible tube. The motion of the compressed region of the tube along its axis forces fluid ahead and creates a partial vacuum behind the region. This partial vacuum forces more fluid forward. The pump has a Rotor Assembly which rotates an attached set of rollers up against a tube backed by a fixed circular wall called the Stator. The rotary motion of the Rotor Assembly around the center axis of the pump forms the region of moving compression in the tube.
8.2 Design Considerations
One side effect of the friction between the Rollers and the tube is a net force on the tube in its axial direction. When unchecked, this force tends to cause the tube to “creep” or move forward. A pump must have some type of mechanism to counter this force. In addition, is must give customers the ability to change the tubing quickly, to use the same pump with a wide variety of tube diameters and materials, and to stack more than one pump onto a motor.
8.3 Design Solution
The peristaltic pump provides a novel solution to today’s customer needs. In this design a Rotor Assembly consists of two stainless steel rotors which sandwich three rollers between ball bearings. The Rotor Assembly is rotated by a Rotor Shaft, driven by a pump motor. The Rotor Assembly is supported by a pump base. A stator is mounted to the Base and acts as a tubing compression surface for peristaltic pumping of fluid when in the closed position. In addition, the tight fit of the mating areas of the Stator and the Lower Shield (also mounted to the Base) acts to fully enclose the pump region. This enclosure prevents splashing of fluid in the event that the tubing fails and fluid leaks.