Peristaltic pumps, also known as hose or tube pumps, work with a positive displacement. The fluid is transported through the pipeline by squeezing the flexible tube onto the pump casing through a rotating roller.
As the roller moves over the pipe, it expands and creates a vacuum to allow more fluid to enter. During operation, at least one roller closes the pipe. Therefore, valves are no longer needed. The drum is turned directly by the motor or gearbox.
Peristaltic pumps are ideal for corrosive and viscous fluids because the only part of the pump that comes into contact with the fluid is the pipeline. Because the tubing or pump head is easy to replace, the pump is relatively low maintenance and requires little maintenance. Therefore, industrial peristaltic pumps and medical peristaltic pumps are among the most popular applications for tubular pumps.
When it comes to examples in the medical device industry, peristaltic pumps are used to handle sterile fluids, dialysis, filtration, or biological processing. In the food, agriculture, or sterilization markets, they are used to dispense food or beverages, vitamins, or chemicals. Environmental departments use hose pumps for wastewater treatment or condensate removal in gas analysis applications.
Dry running. Self-priming.
Reversible (DC).
Flow regulation. Ideal for use with viscous or corrosive media.
Resistant to particle contamination.
Common motor types for peristaltic pumps include brushed DC (DC), brushless DC (BLDC), alternating current (AC), or stepper motors. If the hose pump is driven without a gearbox, changing the motor speed can control the flow. Typical motor speeds for peristaltic pumps range from 0-400 revolutions per minute. Typically, DC and BLDC motors are used in conjunction with a gearbox to set the speed as needed for the flow rate. The stepper motor speed can be adjusted by using an external controller board.
How long do peristaltic pumps last?How do I control the flow rate of a peristaltic pump?
The flow rate is proportional to the speed of the motor. This makes peristaltic pumps suitable for dispensing and metering applications. In order to choose the right motor, there are several aspects to consider. DC motors are available in different quality classes and range from 500 to 4000 hours of operation. The limiting factors for these motors are the brush system and bearings. In AC motors, the shadow pole variant has a lifespan of 1000 hours, and the capacitor version has a lifespan of more than 10000 hours.
In the case of stepper and brushless DC motors, the limiting aspect is usually just the bearing system. In BLDC and stepper motors, the speed can be adjusted very easily during operation. These motor types are often used when variable flow is required.
Typical peristaltic hose or hose materials range from silicone to thermoplastic vulcanizate (TPV) or PVC to fluoroelastomer materials. Silicone is often used when non-corrosive media need to be pumped. Compared to other materials, silicone is at the softer end of the range. TPV combines the processability of polypropylene with the elastic properties of EPDM. Commonly used TPV-based tubing materials are Pharmed BPT or Santoprene. When more chemically aggressive media need to be pumped, fluoroelastomer materials such as Viton can be used.
When it comes to choosing the right pipe, it's crucial to choose the right pipe size. When maximum tube life is key, tubes with larger bore and low motor speeds are advantageous. For higher flow rates, large bore pipes and high motor speeds should be chosen. When the application requires high precision, the tubing should have a minimum internal diameter and the motor speed should be high. For pumping, viscous liquid tubing should have a high wall thickness to ensure a quick return to its original shape.
Particles in pipes can fall off into the fluid cycle, a process known as spallation. Spallation should be avoided, especially in biological, pharmaceutical, or medical applications. Special types of TPV materials exist, such as versalloy, that provide optimized properties to reduce spallation.
To reduce pulsation, many peristaltic pumps offer a spring-loaded mechanism to ensure a smooth pumping action. This feature is also important for shear-sensitive fluids, such as living cells. Another aspect to consider is adjusting the pump to different tube sizes depending on the desired flow rate.
More complex pump types also have adjustable occlusion. This feature helps to adjust the pump to the different pressure levels that may occur in the fluid system. In addition, it helps to adjust the performance of the pump according to different pipe materials. Depending on the type of fluid, softer tubing made of silicone resin is used, while for chemically demanding applications, fluoroelastomer materials are required. These are usually much more difficult.
Peristaltic pumps stand out for their ease of use. Tubing or pump heads can be replaced in seconds. The design without the need for internal valves has different advantages. It can be operated clockwise and counterclockwise, so the liquid can be transferred in both directions if the process requires it. Since there are no valves, there are fewer restrictions in the pipeline, which helps to help when viscous media need to be transferred.
To increase the efficiency of the product, a multi-channel peristaltic pump can be used. In this type of pump, a motor drives a pump head with up to 15 channels, each containing a separate pipe. In this way, different media can be transferred at the same time, and the same media can also be distributed into multiple containers. The number of rollers used in a peristaltic pump has a significant impact on fluid handling. For higher flow rates, only two or three rollers are used. The downside of this is that the pulsation is high. If gentle transfer of media is required, more rollers are usually used to maintain moderate pulsation.
An important requirement in many medical or analytical processes is to avoid cross-contamination. The tubing is the only part that comes into contact with the medium and can be easily closed after each process cycle.
Other applications include detergent dispensing in industrial dishwashers, condensate removal in continuous emissions monitoring, or dialysate transfer in dialysis machines.