Peristaltic pumps operate in the principle of compressing and decompressing fluid. It utilizes “shoes” or rollers that are fixed onto the rotor of the pump, which press the fluid through the pump. After a fixed volume of fluid (which is defined by the distance between the two rollers or shoes) is drawn into the pump tube, it is trapped by the roller or shoes, rotated, and expelled out of the pump when the next roller or shoe passes over the tube. As the rollers start to make another rotation, a new vacuum is formed, causing more fluid to be drawn into the pump.

The complete closure of the tube when it is squeezed between the rollers and the track is what gives the peristaltic pump its positive displacement action.