1. What is the working principle of the peristaltic pump
The peristaltic pump is like squeezing a stick with your fingers A fluid-filled hose moves the fluid forward as the finger slides forward. The same principle applies to peristaltic pumps, but the fingers are replaced by rollers. Fluid is pumped by alternately squeezing and releasing the elastic delivery hose of the pump. Just like squeezing a hose with two fingers, with the movement of the fingers, a negative pressure is formed in the tube, and the liquid flows with it. The peristaltic pump forms a “pillow”-shaped fluid in a section of pump tube between two rotating rollers. The volume of the “pillow” depends on the inner diameter of the pump tubing and the geometry of the rotor. The flow rate depends on the product of the speed of the pump head, the size of the “pillow”, and the number of “pillows” produced by each revolution of the rotor. The dimensions of the “pillow” are generally constant (except when pumping very viscous fluids). Comparing pumps with the same rotor diameter, a pump with a larger “pillow” volume has a larger volume of fluid delivered per revolution of the rotor, but also generates a larger degree of pulsation. This is similar to the case of membrane valves. In a pump that produces a smaller “pillow” volume, the volume of fluid delivered by the rotor per revolution is also smaller; moreover, the small “pillow” formed rapidly and continuously makes the fluid flow more stable. This is similar to how a gear pump works.
Second, analysis of the advantages and disadvantages of peristaltic pumps
Advantages
1. No pollution: the fluid only contacts the pump tube, not the pump body.
2. High precision: repeatability, high stability and precision.
3. Low shear force: It is an ideal tool for conveying shear-sensitive and aggressive fluids.
4. Good sealing: It has good self-priming ability, can be idling, and can prevent backflow.
5. Simple maintenance: no valves and seals.
6. It has the ability to convey the same flow in both directions; it will not cause damage to any part of the pump under the condition of no liquid idle operation; it can produce up to 98% vacuum; there is no valve, mechanical seal and packing seal device , there are no factors that cause leakage and maintenance; it can easily transport solid, liquid or gas-liquid mixed-phase fluid, allowing the solid diameter contained in the fluid to reach 40% of the inner diameter of the tubular element; it can transport a variety of abrasive, corrosion, oxygen Materials with sensitive properties and various foods; only the hose is the part that needs to be replaced, and the replacement operation is extremely simple; except for the hose, the conveyed product does not come into contact with any parts.
Limitations
1. Pressure limitation: The use of flexible pipes will limit the pressure.
2. The pump will generate a pulse flow during operation, the solution is: use a pulse suppressor. The pulse suppressor is a simple positioning container. The working principle is that because air is more compressible than liquid, the pulse flow enters the container, and the air pocket on the liquid sinks to absorb the pulse and then flows out of the pulse suppressor smoothly.
3. The peristaltic pump achieves the change of flow by adjusting the speed and changing the inner diameter of the pump tube, and the flow range of the peristaltic pump is relatively narrow.
