Have You Used a Pump Today?

If you are reading this, then the answer is yes. Everyone uses some type of pump every day. Pumps are so commonly used that we hardly realize how important they are to us. A pump is any device that moves a fluid from one location to another.  Therefore if you have a heart, then you are using a pump at this very moment to pump blood throughout your body. Your heart pumps blood similar to a diaphragm pump and your arteries and intestines act like peristaltic pumps. Within your heart, muscle tissue displaces blood while valves help control the direction of blood flow, ensuring a consistent unidirectional flow of blood. Both arteries and veins have smooth muscle tissue to maintain the flow and pressure of blood moving throughout our bodies.  The smooth muscle tissue acts like the rollers of a peristaltic pump to contract arteries (like tubing) to move blood flow in a specific direction.

How Peristaltic Pumps Work:

Peristaltic pumps operate on a simple principle. The alternating pattern of squeezing and releasing the tubing moves the fluid through the pump. One of the many advantages offered by peristaltic pumps is the ability to isolate fluid within the tubing (much like our blood flow).

As a roller passes over the tubing, it is first occluded (squeezed), then released. The progression of this squeezed area forces fluid to move in front of the roller. The tubing behind the rollers recovers its shape, creates a vacuum, and draws fluid in behind it. As the roller moves faster, vacuum pockets are created more quickly and the fluid moving through the system picks up speed. The rollers act as check valves to prevent siphoning or loss of prime.

The distance between the rollers creates a “pillow” of fluid. This volume is specific to the ID of the tubing and the geometry of the rotor. Flow rate is determined by multiplying pump head speed by the size of the pillow by the number of pillows per revolution. This pillow volume stays very constant except with highly viscous fluids. Among pumps with the same diameter of rotor, pumps with large pillows will deliver higher volumes of fluid per revolution. A greater degree of pulsation exists with these higher flow rates, not unlike the pumping profile of a diaphragm pump. Pumps with small pillows deliver small volumes of fluid per revolution.

Applications:

Using this knowledge of how peristaltic pumps transfer fluids through enclosed tubing, many entrepreneurs have found

ways to incorporate similar pump systems into their business.  One resourceful maple syrup producer in upper New York found a clever use for a peristaltic pump. Rascher’s Sugar House installed seven miles of food-grade plastic tubing running from maple trees on his property.  Rascher ordered a Masterflex® B/T® Variable-Speed Pump from Cole-Parmer and by using his peristaltic pump, he was able to pump maple sap from his trees, through the tubing, through filters, and into a holding tank.

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