Q&A about Peristaltic Pumps

Find answers to frequently asked questions about peristaltic pumps. Learn about operating principle, flow rate, dosing, viscosity, pump tubing, chemical resistance, IP ratings, pump heads, external control and selecting the right pumping solution.

Peristaltic pump basics

A peristaltic pump is used for dosing and transferring fluids in applications such as laboratories, production facilities and process equipment. Peristaltic pumps are used in industries including pharmaceutical manufacturing, biotechnology, food production, the chemical industry, water treatment, research and machine building.

Below you will find answers to frequently asked questions about peristaltic pumps, including flow rate, dosing, viscosity, pump tubing, chemical resistance, pump heads, IP ratings, external control and pump selection.

How does a peristaltic pump work?

A peristaltic pump transfers fluid by using rollers in the pump head to compress flexible pump tubing. As the rollers move along the tubing, the fluid is pushed forward through the tube.

During normal operation, the fluid only comes into contact with the pump tubing and not with the mechanical components of the pump. This makes peristaltic pumps suitable for many applications where cleaning, product changeover or the risk of contamination are important considerations.

What are the advantages of a peristaltic pump?

One of the main advantages of a peristaltic pump is that the fluid only comes into contact with the pump tubing. The pumping principle also allows for self-priming, dry running and flow adjustment by changing the pump speed.

Other typical advantages include:

• Suitable for both continuous fluid transfer and dosing
• Can handle many viscous and particle-containing fluids
• Few product-contact components
• Relatively simple maintenance
• Wide range of pump tubing for different fluids and processes
• Integration into automated processes is possible with many pump models

Suitability always depends on the specific combination of pump, pump head, pump tubing, fluid and operating conditions.

Is a peristaltic pump self-priming?

Yes. Peristaltic pumps are self-priming. When the pump tubing returns to its original shape after being compressed by a roller, negative pressure is created, drawing fluid into the tubing.

The actual suction capability depends on factors including the pump type, pump head, pump tubing, speed, fluid properties and installation.

Can a peristaltic pump run dry?

Yes. A peristaltic pump can normally operate without fluid in the pump tubing because its mechanical components do not depend on the pumped fluid for lubrication.

However, the pump tubing is still mechanically compressed by the rollers during dry running. Prolonged unnecessary dry running can therefore contribute to tubing wear.

Flow rate, dosing and process conditions

How accurate is a peristaltic pump?

Peristaltic pumps can provide good repeatability and are suitable for both dosing and continuous fluid transfer. However, actual dosing and flow accuracy depend on the complete application.

Factors that can affect accuracy include:

• Pump head
• Pump tubing dimensions
• Tubing material
• Pump speed
• Fluid viscosity
• Temperature
• Suction lift and back pressure
• Age and mechanical properties of the tubing

For precision dosing applications, it may be necessary to calibrate the pump using the actual fluid and under the actual process conditions.

What determines the flow rate of a peristaltic pump?

The flow rate of a peristaltic pump is primarily determined by the pump speed, pump head design, and the internal diameter and wall thickness of the pump tubing.

A larger internal tubing diameter will generally provide a higher flow rate at the same pump speed. However, the actual flow rate can also be affected by viscosity, back pressure, suction lift, temperature and the mechanical properties of the tubing.

The manufacturer's stated flow data should therefore be evaluated in relation to the test conditions on which the data are based.

How does back pressure affect the flow rate of a peristaltic pump?

Increasing back pressure can reduce the actual flow rate of a peristaltic pump. The extent of this effect depends on factors including the pump head, pump tubing, speed and overall resistance of the system.

If an application involves significant back pressure, the pump should therefore be sized according to the actual process conditions rather than solely on its nominal flow rate.

Can a peristaltic pump handle viscous fluids?

Yes. Peristaltic pumps can be used with many viscous fluids, although increasing viscosity can reduce both suction capability and achievable flow rate.

When pumping viscous fluids, it is particularly important to select an appropriate tubing size and pump speed and to minimise unnecessary resistance on the suction side of the pump.

Drifton can help assess a suitable pumping solution based on the viscosity of the fluid, the required flow rate and other process conditions.

Can a peristaltic pump handle fluids containing particles?

Yes. In many cases, peristaltic pumps can handle particle-containing fluids because the fluid is transferred through flexible tubing without passing through product-contact valves or small mechanical components.

However, particle size and concentration must be suitable for the internal diameter of the pump tubing and the specific application. Abrasive particles may also reduce pump tubing life.

Does a peristaltic pump produce pulsating flow?

Yes. Peristaltic pumps naturally produce some pulsation because the rollers in the pump head alternately compress and release the pump tubing.

Pulsation is affected by factors including:

• Number of rollers in the pump head
• Pump speed
• Pump tubing dimensions
• Pump head design

A pump head with more rollers can typically provide a smoother flow and reduce pulsation. At the same time, more rollers will typically reduce the flow per revolution compared with a similar pump head with fewer rollers.

Can a peristaltic pump be used at high pressure?

Peristaltic pumps are generally used for fluid transfer and dosing at moderate pressures. The maximum operating pressure depends on the specific combination of pump head, pump tubing and operating conditions.

As increasing back pressure can also reduce flow rate, applications involving higher pressures should be sized specifically according to the actual process conditions.

Can a peristaltic pump run continuously?

Many peristaltic pumps can be used for continuous operation, but suitability depends on the specific pump model, pump head, pump tubing, speed and operating conditions.

Continuous operation places ongoing mechanical stress on the pump tubing. For long-term or 24/7 operation, the expected tubing life and the need for planned tubing replacement should therefore be considered when selecting the pumping solution.

Pump tubing and chemicals

Can a peristaltic pump be used with aggressive chemicals?

Yes, in many cases. Since the fluid normally only comes into contact with the pump tubing, selecting a chemically compatible tubing material is essential.

Chemical compatibility should always be evaluated based on the specific chemical, concentration, temperature and exposure time.

If the pump may also be exposed to chemical splashes or vapours, the materials used in the pump head and other exposed components should also be evaluated.

Which pump tubing should I choose?

The appropriate pump tubing should be selected according to the fluid and process conditions. Tubing material and dimensions affect factors including chemical compatibility, flow rate, dosing accuracy and service life.

When selecting pump tubing, factors to consider include:

• Chemical composition of the fluid
• Concentration
• Temperature
• Viscosity
• Operating pressure
• Required flow rate
• Required service life
• Sterility requirements
• Regulatory documentation requirements
• Any requirements for weldability or connection to other tubing systems

Pump tubing is available in materials including silicone, TPE and various specialised materials for chemically demanding applications.

Is pump tubing a wear part?

Yes. Pump tubing is a wear part because it is repeatedly compressed by the rollers in the pump head during operation.

Tubing life is affected by factors including:

• Pump speed
• Pressure
• Temperature
• Tubing material
• Chemical exposure
• Pump head design
• Operating time

Regular inspection and planned replacement of the pump tubing may be appropriate in processes where downtime or tubing failure needs to be minimised.

Can the age of the pump tubing affect flow rate and dosing accuracy?

Yes. The mechanical properties of pump tubing can change over time as a result of repeated compression, temperature and chemical exposure. This can affect the tubing's ability to return to its original shape and thereby alter the actual flow rate.

In applications with high requirements for dosing accuracy, the pump tubing should therefore be inspected and replaced at appropriate intervals. Recalibrating the pump after replacing the tubing may also be beneficial.

Can a peristaltic pump be used for sterile or hygienic processes?

Yes, depending on the specific pump tubing and process. Since the fluid only comes into contact with the tubing, peristaltic pumps can be suitable for many hygienic and sterile fluid-handling processes.

Pump tubing is available with documentation for applications including pharmaceutical manufacturing, biotechnology and food production, as well as in pre-sterilised tubing configurations.

Depending on the application, requirements may include material documentation, biocompatibility, sterilisation method and sterility. These requirements should be established before selecting the pump tubing.

Pump head and operating environment

Which pump head should I choose for chemicals and high temperatures?

The pump head material should be selected according to the environment in which the peristaltic pump will operate. Although the fluid normally only comes into contact with the pump tubing, the pump head may be exposed to chemical splashes, chemical vapours or elevated temperatures.

Pump heads are manufactured from various engineering plastics and metals. PPS, for example, may be relevant in chemically demanding environments because of its generally good chemical and thermal properties.

However, material suitability must be evaluated according to the specific chemical, concentration, temperature and exposure time. The specified maximum operating temperature of the pump and pump head must always be observed.

For demanding applications, the pump tubing, pump head and other exposed components should therefore be evaluated as a complete system.

Which IP rating should a peristaltic pump have?

The required IP rating depends on the environment in which the pump will be installed. The IP rating describes the enclosure's protection against access to hazardous parts and the ingress of solid foreign objects and water.

The first digit of the IP rating describes, among other things, protection against solid foreign objects, while the second digit describes protection against water.

For normal use on a dry laboratory bench, a lower IP rating may often be sufficient. In production and process environments where the pump may be exposed to dust, splashes or water jets, a higher IP rating may be required.

A pump with an IP66 rating, for example, has a dust-tight enclosure and protection against powerful water jets. IP66 does not mean that the pump is suitable for immersion in water.

The IP rating also does not describe the pump's chemical resistance. If the pump is exposed to aggressive chemicals or chemical vapours, the chemical compatibility of the materials must be evaluated separately.

Does a peristaltic pump require much maintenance?

Peristaltic pumps generally have relatively low maintenance requirements. Since the fluid only comes into contact with the pump tubing, the pump does not have product-contact valves, seals or impellers found in many other types of pump.

The pump tubing is the primary wear component and should be inspected and replaced as required.

For industrial installations, regular inspection of the pump head, rollers, coupling and other mechanical components may also be appropriate.

Control and selection of peristaltic pumps

Can a peristaltic pump be controlled by a PLC or another external system?

Yes. Many peristaltic pumps can be integrated into automated production, process and dosing systems.

Depending on the pump model, available control options may include:

• External start/stop
• Analogue speed control
• 0–5 V or 0–10 V signal
• 4–20 mA signal
• Pulse or frequency control
• RS485
• Modbus
• RS232

The available control options and communication interfaces depend on the specific pump model.

What is the difference between a laboratory pump and an OEM peristaltic pump?

A laboratory peristaltic pump is typically supplied as a complete, freestanding unit with an enclosure and control panel. It is suitable for applications including laboratories, research, development, test setups and smaller production processes.

An OEM peristaltic pump, on the other hand, is designed for integration into a machine or instrument. OEM pumps can be used in applications such as analytical instruments, dosing systems and other automated equipment.

OEM solutions are available with different motors, pump heads and control options depending on the application.

When should I choose a pump head with more rollers?

A pump head with more rollers may be appropriate when reduced pulsation and smoother flow are priorities. The number of rollers affects factors including flow rate, pulsation and how frequently the pump tubing is compressed.

At the same time, a higher number of rollers will typically result in a lower flow per revolution than a comparable pump head with fewer rollers.

The choice therefore depends, among other factors, on whether the application primarily requires a high flow rate or smoother flow with reduced pulsation.

How do I choose the right peristaltic pump?

The appropriate peristaltic pump should be selected according to the fluid, required flow rate and actual operating conditions. The pump, pump head and pump tubing should be considered as one complete pumping solution.

To select a suitable peristaltic pump, you should know at least the following:

• Required flow rate, for example in ml/min or L/min
• Required dosing volume and dosing frequency, if applicable
• Fluid type and chemical composition
• Viscosity
• Fluid and ambient temperature
• Suction lift and back pressure
• Pump tubing material requirements
• Chemical resistance requirements
• Sterility or documentation requirements
• Required IP rating
• Any ATEX requirements
• Requirements for external control or PLC communication
• Whether the pump will be used for continuous or intermittent operation

Do you need help selecting a peristaltic pump?

Drifton offers peristaltic pumps ranging from compact laboratory and dosing pumps to OEM pumps and industrial peristaltic pumps for higher flow rates.

Contact Drifton with information about the fluid, required flow rate or dosing volume, viscosity, temperature, back pressure and operating environment. We can help you find a suitable combination of peristaltic pump, pump head and pump tubing for your application.