What Is Peristaltic Pump And How Does It Work?

A class of positive displacement pumps is the peristaltic pump. The peristalsis principle serves as the cornerstone on which the pumps are built. Peristalsis is a series of muscular contractions that transport food to various locations along the digestive system in a biological sense.

Peristaltic Pump Work

Positive displacement is the mechanism used by peristaltic pumps, also known as hose or tube pumps. A flexible tube is compressed against the pump housing as it is fed fluid by rotating rollers.

The tubing expands as the roller passes over it, creating a vacuum that lets more fluid flow through. In use, the tubing is sealed off by at least one roller. As a result, valves are no longer required. Either an electric motor or a gearbox turns the rollers in place.

Positive displacement pumps that transfer a variety of fluids include peristaltic pumps. This pump is simple to maintain because it lacks valves, seals, and glands. Every peristaltic pump has flexible hoses or tubes that provide an open flow path with high resistance to abrasion and enable the simple flow of solids and viscous media.

Working Principle Of A Peristaltic Pump

A peristaltic pump’s basic operating concept is the compression and decompression of a product to move it through a hose. The pump’s rotor presses fluid through it while the “shoes” of the pump are fixed to it. Similar to how our bodies pump blood, nutrients, and oxygen so does this system.

Types Of Peristaltic Pumps

Peristaltic pumps come in two different varieties: hose pumps and tube pumps. Hose pumps are ideal for pumping highly solid content, while tube pumps work best for lower flow rates, are fully programmable, and offer multiple heads.

Peristaltic Pumps Advantages

• Dry running
• Self-priming
• Reversible (DC)
• Flow regulation
• Excellent for use with viscous or aggressive media
• Tolerant to contamination with particles
• Thomas peristaltic pumps offer flow rates up to 2000 ml/min, suction height up to 9 m H₂O, pressure height up to 100 m H₂O

Types Of Motors For Peristaltic Pumps

Brushed direct current, brushless direct current, alternating current, and stepper motors are typical motor types for peristaltic pumps. The flow can be managed by adjusting the motor speed if the hose pump is powered without a gearbox. Peristaltic pumps typically have motor speeds between 0-400 revolutions per minute. Typically, a gearbox and DC and BLDC motors are used to adjust speed based on the flow requirement. Using an external controller board, stepper motor speeds can be controlled.

Peristaltic Pumps Used

Because only the tubing of the pump comes into contact with the fluid, peristaltic pumps are perfect for use with corrosive and viscous fluids. The pumps are practically maintenance-free and relatively inexpensive to maintain because the tubing or the head is easily replaceable. As a result, peristaltic pumps used in industry and medicine are among the most widely used peristaltic pump tube pumps.

For processing sterile fluids, dialysis, filtration, or bioprocessing, peristaltic pumps are used in the medical device industry. They are employed to dispense food or drink, vitamins, or chemicals in the food, agricultural, or disinfection industries. Hose pumps are used in the environmental sector to treat wastewater or remove condensate from gas analysis applications.

Flow Rate Controlled In Peristaltic Pumps

Motor speed affects flow rates in a direct relationship. Peristaltic pumps are thus suitable for dosing and dispensing tasks. There are a few factors to take into account when selecting the right motor. Direct current motors are offered in various quality levels with operating times ranging from 500 to 4000 hours. The brush system and the bearings are those motors’ limiting elements. The lifetime of an AC motor varies from 1000 hours for shaded pole versions to more than 10,000 hours for capacitor versions.

The bearing system is typically the only constraining factor in the case of stepper and brushless DC motors. The speed can be changed easily while the motor is running in both BLDC and stepper motors. When a variable flow rate is required, those motor types are frequently used.

All About Tubing Of Peristaltic Pump

The materials used to make peristaltic pump hoses or tubes typically range from silicone to fluoroelastomer materials over thermoplastic vulcanizate (TPV) or PVC. When non-aggressive media needs to be pumped, silicone is frequently used. Silicone is on the softer side of the spectrum when compared to other materials. TPV combines the simple processing of polypropylene with the elastomeric characteristics of EPDM. The tubing materials Pharmed BPT or Santoprene are frequently used because they are based on TPV. Fluoroelastomeric materials like Viton are used when pumping more chemically corrosive media.

The correct selection of tubing dimensions is essential when making the right tubing choice. When maximizing peristaltic pump tube lifespan is essential, a tube with a larger inner diameter and slow motor speed is beneficial. Large inner diameter tubing and a fast motor speed should be used for flow rates that are higher. When a high degree of accuracy is required, the motor speed should be high and the tubing should have a small inner diameter. Viscose liquids should be pumped through tubes with thicker walls so that the original shape can be recovered quickly.

The process of spallation occurs when particles from the tubing are shed into the fluid ring. In particular, spallation should be avoided in biological, pharmaceutical, or medical applications. There are specific TPV material types with optimized properties to lessen spallation, such as Versalloy&trade.

Factors Take Into Account When Buying Peristaltic Pumps

Many peristaltic pumps offer a spring-loaded mechanism to ensure smooth pumping action in order to lessen pulsation. Furthermore, shear-sensitive fluids like living cells require this feature to function properly. The adjustment of the pump to various peristaltic pump tube dimensions depending on the required flow rate is another factor to take into account.

An adjustable occlusion is another feature of more advanced peristaltic pump types. This feature can assist in adjusting the pump to various pressure levels that may be present in fluidic systems. Additionally, adjusting the pump’s performance to different tubing materials is helpful. Silicone tubings vary in hardness depending on the fluid type, while fluoroelastomer materials are required for applications requiring aggressive chemicals. Those are typically much more difficult.

The simplicity of use makes peristaltic pumps unique. It takes just a few seconds to swap out the tubing or pump head. A design without internal valves has a variety of benefits. If the process demands it, liquids can be transferred in both directions because both clockwise and counterclockwise operations are possible. Since there are no valves, the tubing is less constrained, which is advantageous when moving viscous media.

Multiple-channel peristaltic pumps may be used to improve the product’s efficiency. These pumps use a single motor to power a pump head with up to 15 channels, each housing a separate peristaltic pump tube. With that, multiple vessels can receive the same medium at the same time or receive different media simultaneously. Fluid handling is significantly impacted by the number of rollers used in peristaltic pumps. Just two or three rollers are utilized for higher flow rates. The high pulsation is a drawback to this. More rollers are frequently used to keep the pulsation at a moderate level when a gentle medium transfer is necessary.

Cross-contamination prevention is a key requirement in many medical or analytical processes. Only the peristaltic pump tubes, which are simple to replace after each cycle of the process, come into contact with the medium.
Other uses include the transfer of dialysate in dialysis machines, the dispensing of detergent in commercial dishwashers, and the removal of condensation in continuous emissions monitoring.

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