A positive displacement pump that consists of a flexible tube which contains the process fluid to be transported. The tube is compressed and squeezed between rollers on a rotating wheel thereby moving the fluid along the tubing (see Fig. 35). The roller pressure traps portions of the fluid and carries them forward as discrete volumes. The flow is, however, not pulsation-free. The rate of flow is adjusted by changes in the rotational speed of the wheel. By maintaining the fluid in the sealed tube such that it has no contact with the moving parts of the pump, it is therefore often used in medical applications for fluids such as blood, and for metering applications.

Fig. 35