How does a liquid peristaltic pump work?

Peristaltic pumps, also known as hose or tube pumps, use positive displacement to work. Fluid is piped through a rotating roller that squeezes the flexible tube onto the pump housing.

As the roller moves across the pipe, it expands and creates a vacuum to allow more fluid to enter. At least one roller closes the pipe during operation. So the valve is no longer needed. The drum is rotated directly by a motor or gearbox.

Where is the peristaltic pump used?

Peristaltic pumps are ideal for use with corrosive and viscous fluids because the only part of the pump in contact with the fluid is the pipe. The pump is relatively cheap to maintain and almost maintenance-free because the pipe or pump head is easy to replace. Therefore, industrial peristaltic pumps and medical peristaltic pumps are one of the most popular applications of tube pumps.

Speaking of examples from the medical device industry, peristaltic pumps are used to handle sterile fluids, dialysis, filtration, or biological treatments. In food, agriculture or disinfection markets, they are used to distribute food or beverages, vitamins or chemicals. The Environmental Department uses hose pumps for wastewater treatment or condensate removal in gas analysis applications.

What are the benefits of peristaltic pump technology?

Dry running

self-priming

Reversible (DC)

Flow control

Ideal for use in viscous or corrosive media

Tolerance to particle contamination

What are the types of peristaltic pump motors?

Common motor types for peristaltic pumps include brushless DC (DC), brushless DC (BLDC), alternating current (AC), or stepper motors. If the hose pump is driven without a gearbox, flow can be controlled by changing the motor speed. A typical motor speed range for a peristaltic pump is 0-400 revolutions per minute. Typically, DC and BLDC motors are used with a gearbox to set the speed as required for flow. The stepper motor speed can be adjusted by using an external controller board.

How long will the peristaltic pump last? How to control the flow of peristaltic pump?

The flow rate is proportional to the motor speed. This makes peristaltic pumps suitable for distribution and metering applications. In order to choose the right motor, there are several aspects to consider. Dc motors are available in different quality grades with operating hours ranging from 500 to 4000 hours. The limiting factors for these motors are the brush system and bearings. In the AC motor, the shaded pole variant has a service life of 1000 hours and the capacitor version has a service life of over 10.000 hours.

For 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 commonly used when variable flow rates are required.

All about peristaltic tubes

Typical peristaltic hose or hose materials range from silicone to thermoplastic vulcanized rubber (TPV) or PVC to fluororubber materials. Silica gel is usually used when non-corrosive media need to be pumped. Silica gel is at the softer end of the spectrum compared to other materials. TPV combines the workability of polypropylene with the elastic properties of EPDM. Commonly used TPV-based tubing materials are PharMed® BPT or Santoprene™. Fluororubber materials such as Viton® can be used when more chemically aggressive media need to be pumped.

When choosing the right pipe, it is very important to choose the right pipe size. When maximum tube life is key, tubes with large inner diameters and low motor speeds are advantageous. For higher flow rates, large inner diameter pipes and high motor speeds should be selected. When high accuracy is required for the application, tubing should have a minimum inner diameter and motor speed should be high. For pumping, the viscous liquid tube should have a high wall thickness to ensure a quick return to the original shape.

Particles in the pipe may fall off into the fluid circulation in a process called spallation. Spallation should be avoided, especially in biological, pharmaceutical or medical applications. Special types of TPV materials exist, such as Versalloy™, which provide optimized properties to reduce spallation.

What should be considered for peristaltic pumps?

To reduce pulsation, many peristaltic pumps provide spring loading mechanisms to ensure smooth pumping action. This function 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 pump performance according to different pipe materials. Depending on the type of fluid, softer pipes made of silicone are used, while for chemically demanding applications, fluoroprene materials are used. These are usually much more difficult.

Peristaltic pumps stand out for their ease of use. The pipe or pump head can be replaced in seconds. Designs that do not require internal valves have different advantages. It can be operated clockwise and counterclockwise, so the liquid can travel both ways if the process requires it. Because there are no valves, there are fewer restrictions in the pipeline, which helps when sticky media need to be transferred.

In order to improve the efficiency of the product, a multi-channel peristaltic pump can be used. In this pump, a motor drives a pump head with up to 15 channels, each containing a separate pipe. In this way, different media can be transmitted simultaneously or the same media can be distributed among 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 pulse is very high. If the medium needs to be gently transferred, more rollers are usually used to maintain a moderate pulsation.

An important requirement in many medical or analytical procedures is to avoid cross-contamination. The tube is the only part in contact with the medium and can be easily closed after each process cycle.

Other applications include detergent distribution in industrial dishwashers, condensate removal in continuous discharge monitoring, or dialysate transfer in dialysis machines.