What would not affect pulsation flow on a roller pump?

• A. RPMs
• B. Tubing occlusion
• C. Viscosity
• D. Roller diameter

Answer: (A)

Pulsatile flow in a roller pump comes from the tubing being compressed by the rollers as they pass. The size of each pulse—the amount of fluid moved in a single compression event—depends on how much the tubing is occluded, how elastic the tubing is, and the volume displaced by each roller (which relates to roller geometry). The fluid’s viscosity affects how easily that pulse propagates and can damp or shape the pulse, altering its appearance but not the basic mechanism of a pulse.

What changes the pulse rate or the overall flow is how fast the rollers rotate. Increasing RPMs raises how often those compression events occur and increases the average flow, but it does not change the per-pulse volume if occlusion and tubing characteristics stay the same. So RPMs would not affect the magnitude of the pulsation itself, only its frequency and the total throughput.