“How to choose a peristaltic pump and understand its working principle.”
A peristaltic pump is a liquid delivery device that allows controlled flow rate due to its ability to stabilize and control fluid speed. It offers advantages such as pollution-free fluid transport, simple and inexpensive maintenance,
high delivery accuracy, strong corrosion resistance, minimal shear effects, ease of operation, and easy maintenance.
As a result, it finds extensive applications in various fields, including research, pharmaceuticals, chemical engineering, environmental protection, beverages, food, agriculture, and printing.
It is commonly used in research laboratories for tasks such as cell and tissue transportation, specimen decolorization, perfusion, liquid chromatography analysis, and the delivery of acidic or alkaline solutions.
Let's provide a brief introduction to peristaltic pumps and related knowledge:
Catalog：
- What is a peristaltic pump?
- Composition of a peristaltic pump
- Working principle of a peristaltic pump
- Analysis of the working principle
- Classification and application scenarios of peristaltic pumps
- Advantages of peristaltic pumps
- Disadvantages of peristaltic pumps
- Factors to consider when choosing a pump head
- Factors to consider when selecting tubing
1.What is a Peristaltic Pump?
A peristaltic pump, also known as a peristaltic, metering, constant flow, or tubing pump, is referred to as a peristaltic pump based on its precision of delivery, product construction, or working principle.
2.Composition of a Peristaltic Pump:
A peristaltic pump consists of three main parts: the peristaltic pump driver, the pump head, and the peristaltic pump tubing.
It is a liquid delivery device that achieves high-precision flow control by adjusting the driver speed and using different flow rate tubing.
3.Working Principle of Peristaltic Pump:
The peristaltic pump transports liquids by squeezing the tubing, ensuring that the liquid only passes through the tubing without any dead zones in the pump. This design makes it easy to clean and minimizes residue, making it suitable for clean transport purposes.
Additionally, the pump delivers a fixed volume of fluid with each revolution, enabling precise metering by adjusting speed and timing.
The peristaltic state of the tubing is like pushing the fluid inside the tube similar to the movement in the human intestine, so it does not subject the fluid to squeezing and damage.
Therefore, it is suitable for transporting relatively viscous or particulate-containing materials, such as fruit juice with pulp. However, attention should be given to selecting tubing that matches the specific requirements.
When comparing pumps with the same wheel diameter, a pump that generates a larger "pillow" volume will also deliver a larger volume of fluid per revolution, but it will also produce larger pulsations.
On the other hand, a pump that generates a smaller "pillow" volume will deliver a smaller volume of fluid per revolution; the rapid and continuous formation of small "pillows" results in a nearly constant and stable fluid flow rate during transmission.
4.Working Principle Analysis:
(1) The motor drives the wheel to rotate.
(2) The rotating wheel squeezes the pump tubing against the pump casing.
(3) As the wheel rotates, it compresses the tubing in the rear region, pushing the liquid downstream.
(4) As the wheel rotates, it compresses the tubing in the rear region. When the wheel moves away, the elastic pump tubing returns to its circular shape,
creating suction that draws liquid from the upstream. The suction can only attract liquid from the upstream as the squeezed tubing prevents fluid flow in the opposite direction.
(5) The continuous rotation of the wheel results in the continuous intake of liquid from the inlet and discharge from the outlet.
5.Classification and Application Scenarios of Peristaltic Pump:
Based on Flow Rate:
Small Flow Peristaltic Pump: Mainly used in laboratories and medical fields, providing high flow rate accuracy.
Medium Flow Peristaltic Pump: Used in laboratories, medical applications, small-scale production, and distribution, offering high flow rate accuracy.
Large Flow Peristaltic Pump: Primarily used in high flow rate experiments, production filling, distribution, and industrial liquid transport
6.Advantages of Peristaltic Pump:
1.Does not contaminate structures outside the tubing and has no valves or seals.
2.Can operate without liquid filling.
3.Can self-prime without liquid filling.
4.Can handle fluids with a high level of impurities.
5.Can work in both forward and reverse directions.
6.Prevents liquid backflow.
7.Disadvantages of Peristaltic Pump:
1.Tubing aging: The elasticity of the tubing, usually made of rubber or silicone, may deteriorate over time, leading to decreased flow rate or increased fluctuations.
2.Lack of uniformity in multiple pump heads or tubes: Differences in tubing material, thickness, and inner diameter can cause variations in flow rates.
Considerations for Pump Head Selection:
When selecting a pump head, consider factors such as reference flow rate, channel requirements (single-channel or multi-channel), roller requirements (number of rollers), chemical resistance, and ease of tube replacement.
8.Considerations for Tubing Selection:
When selecting tubing, consider factors such as reference flow rate, chemical resistance (compatibility with the transported fluid), fluid temperature resistance, tubing lifespan, and suction and discharge head requirements.
Protection level: The higher the protection level, the better the ability to prevent foreign object intrusion and water immersion. Considering your industry's working environment, choose the appropriate protection level.
When selecting a pump head, five aspects are generally Considered:
Reference flow rate: Different pump heads are equipped with different tubing, resulting in varying flow rates. Therefore, when selecting a pump head, please pay attention to the reference flow rate.
Channel requirements: Channels can be single or multiple. If multiple channels are needed, you can choose a pump head with multiple channels or connect multiple pump heads in series.
Roller requirements: The fewer rollers a peristaltic pump has, the higher the fluid pulsation and the less stable the flow rate. For applications that require high fluid stability, it is recommended to choose a pump head with more rollers.
Chemical resistance: Prolonged use of peristaltic pumps may lead to damage to the pump head due to overflow of fluids. Therefore, chemical resistance should also be considered.
Tubing replacement: If tubing needs to be replaced frequently, it is advisable to choose a peristaltic pump with quick and easy tubing replacement.
When choosing tubing, five aspects should be considered:
Reference flow rate: Different tubing models have different flow-carrying capacities. Choose the appropriate tubing based on your flow rate requirements.
Chemical resistance: Among the three components of the peristaltic pump, the tubing is the part that comes into contact with the fluid. Therefore, chemical resistance of the tubing is a key consideration when choosing.
Fluid temperature: Different tubing materials have different temperature resistance capabilities. Ordinary rubber tubing can generally withstand temperatures up to 100°C, while silicone rubber tubing can withstand temperatures up to 200°C.
Tubing life: The tubing's lifespan may vary depending on usage, but in general, imported tubing tends to have a slightly longer lifespan than domestically produced tubing.
Suction and discharge head: The peristaltic pump relies on the vacuum generated between the rollers to transport fluids using air pressure difference, which results in suction and discharge head.
Suction head refers to the vertical distance between the suction port and the surface of the liquid to be pumped, while discharge head refers to the height to which the pump can lift the fluid.
Various factors, such as tubing material, inner diameter, and wall thickness, will affect the suction and discharge head.
In Conclusion:
The peristaltic pump is a highly versatile liquid delivery device, known for its controlled flow rate, cleanliness, and ease of maintenance.
Its working principle of tubing compression ensures clean and precise metering of fluids.
When choosing a peristaltic pump, consider factors such as flow rate, tubing's chemical resistance, fluid temperature, tubing lifespan, and suction and discharge head requirements.
Despite a few drawbacks, the advantages of peristaltic pumps make them valuable gems in fluid transport applications.
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