Micro Peristaltic Pump: Working Principle, Types, Applications and Selection Guide

Contents List

1. Introduction to Micro Peristaltic Pumps.
2. What Is a Peristaltic Pump?
3. How Does a Micro Peristaltic Pump Work?
4. Main Components of a Micro Peristaltic Pump.
5. Understanding Flow Rate and Pump Tubing.
6. Advantages of Micro Peristaltic Pumps.
7. Limitations and Important Considerations.
8. Micro Peristaltic Pump Electrical Requirements.
9. NKP Micro Peristaltic Pump Models.
10. NKP-DA-S04B 24V 10 mL/min 5W
11. NKP-DE-S04B 6V 10 mL/min 5W
12. NKP-DA-S06B 24V 38 mL/min 5W
13. NKP-DE-S06B 6V 36 mL/min 5W
14. NKP-DC-S06B 12V 37 mL/min 5W
15. How to Select the Right NKP Pump.
16. Applications of Micro Peristaltic Pumps.
17. Installation, Control, and Maintenance.
18. Frequently Asked Questions.
19. Conclusion.

1. Introduction to Micro Peristaltic Pumps

A Micro Peristaltic Pump is a compact positive-displacement pump designed to move small quantities of liquid through flexible tubing.

Unlike conventional water pumps, the liquid inside a peristaltic pump normally contacts only the inner surface of the flexible tube. The pump mechanism does not directly contact the pumped liquid. Instead, rotating rollers compress the tube and move the liquid forward.

This operating principle makes micro peristaltic pumps useful for dosing, dispensing, transferring, and circulating liquids in applications where controlled flow and isolation between the pump mechanism and liquid are important.

The NKP series from Kamoer is an example of a compact Peristaltic Pump family using a DC brushed motor and replaceable tubing. The models discussed in this article provide flow rates from approximately 10 mL/min to 38 mL/min, depending on the model and tubing configuration.

For electronics engineers, makers, and hobbyists, these pumps are particularly interesting because they can be controlled using a DC power supply, switch, motor driver, or PWM-based speed-control circuit, depending on the application and the pump’s electrical requirements.

2. What Is a Peristaltic Pump?

A peristaltic pump is a type of positive-displacement pump that moves liquid by repeatedly compressing and releasing a flexible tube.

The word “peristaltic” comes from the same type of squeezing motion used by the digestive system to move food through the body.

In a mechanical peristaltic pump, one or more rollers rotate around a central rotor. As a roller presses against the flexible tube, the tube becomes temporarily closed at that point.

The rotating roller then moves along the tube. This pushes the liquid in front of the roller while the tube behind the roller returns toward its original shape.

This combination of tube compression, fluid displacement, and tube recovery produces the pumping action.

Because the fluid remains inside the tubing, the pump mechanism itself has very limited direct contact with the liquid.

This is one of the major characteristics that distinguishes a peristaltic pump from many other pump designs.

3. How Does a Micro Peristaltic Pump Work?

Tube Compression

• The flexible tube is installed in the pump head between the rotor and the pump housing.
• When a rotor roller presses against the tube, it compresses the tube and creates an occluded section.
• This prevents liquid from freely flowing backward through that section.

Liquid Displacement

• As the rotor turns, the compressed section moves along the tube.
• The liquid trapped between successive contact points is therefore pushed toward the outlet.
• The amount of liquid moved during each revolution depends on factors such as tube internal diameter, tube geometry, rotor design, and rotational speed.

Suction and Tube Recovery

• After the roller moves away, the flexible tube attempts to return to its original shape.
• This recovery creates a suction effect that draws additional liquid into the inlet side of the tube.
• The cycle then repeats continuously as the rotor turns.

A simplified sequence is:  Compress → Push → Release → Draw in → Repeat

This simple mechanical process is the basic operating principle behind both large industrial peristaltic pumps and small micro peristaltic pumps.

4. Main Components of a Micro Peristaltic Pump

A typical micro peristaltic pump contains several important parts.

 DC Motor

• The motor provides the rotational energy required to operate the pump rotor.
• The NKP models discussed here use DC brushed motors. The required voltage depends on the model, with the selected models operating at 6V, 12V, or 24V DC.

 Rotor and Rollers

• The rotor carries the rollers that compress the flexible tube.
• The NKP models use three rotors/rollers. The three-roller arrangement provides the pumping action while producing a moderate amount of flow pulsation.

Flexible Pump Tube

• The tubing is one of the most important parts of a peristaltic pump.
• The tube is repeatedly compressed by the rollers, so it must have suitable flexibility, dimensions, chemical resistance, and mechanical durability.
• For the S04 NKP models, the listed silicone tube size is approximately 1mm × 3mm.
• For the S06 models discussed here, the listed tube size is approximately 2mm × 4mm.

Pump Housing

• The housing supports the rotor and holds the flexible tube in the correct position.
• Correct tube placement is important because improper positioning can affect flow, increase tube wear, or cause the tube to slip.

5. Understanding Flow Rate and Pump Tubing

Flow rate describes how much liquid the pump can move during a specific period.

It is commonly expressed in:  mL/min — milliliters per minute

For example: a pump rated at 10 mL/min theoretically moves approximately 10 milliliters of liquid per minute under its specified test conditions.

A 38 mL/min pump theoretically moves approximately 38 milliliters per minute under the corresponding conditions.

However, the published flow rate should not be interpreted as an absolute value under every installation condition.

Actual flow can vary because of:

• Supply voltage
• Motor speed
• Tube dimensions
• Tube material
• Fluid viscosity
• Outlet pressure
• Tubing condition
• Temperature
• Pump loading
• Manufacturing tolerances

The NKP datasheet specifically notes that the stated flow figures are reference measurements and that factors such as medium, outlet pressure, and motor-speed variation can affect actual flow.

The internal diameter of the tubing is particularly important.

Increasing the tube diameter can significantly increase the volume displaced during each pumping cycle, which is why the S06 models provide substantially higher flow than the S04 models.

6. Advantages of Micro Peristaltic Pumps

Micro peristaltic pumps offer several useful characteristics for electronics projects, automation systems, laboratories, and dosing applications.

Liquid Isolation

• The liquid remains inside the flexible tube rather than flowing through the motor or most of the mechanical pump assembly.
• This can simplify cleaning and reduce the possibility of contaminating the pump mechanism.

Simple Mechanical Design

• A small peristaltic pump can use a relatively simple mechanical arrangement consisting of a motor, rotor, housing, and flexible tube.
• This makes the technology easy to understand and practical for many DIY and engineering projects.

Self-Priming Capability

• Peristaltic pumps are generally self-priming because the tube is mechanically closed by the rollers during operation.
• However, deliberately priming the tubing before normal operation can help remove trapped air and establish more consistent flow.

Reversible Pumping

• The NKP product documentation states that the direction of rotation can be changed through the motor control.
• This can be useful when a project needs forward and reverse liquid movement.

Easy Tube Replacement

The NKP series is designed with a replaceable pump tube, which is useful because the tube is the component exposed to repeated mechanical compression.

7. Limitations and Important Considerations

Although peristaltic pumps have many advantages, they are not suitable for every application.

Flow Pulsation

• Because the liquid is displaced by discrete roller movements, the output is not perfectly continuous.
• The three-roller NKP design produces moderate pulsation. For applications requiring extremely smooth flow, additional measures may be necessary.

Tube Wear

• The tubing is repeatedly compressed during operation.
• Over time, this mechanical stress can cause the tubing to lose elasticity or eventually require replacement.
• The NKP product specifications list a pump-tube life of approximately 200 hours for the referenced models, but actual service life depends on operating conditions.

Pressure and Fluid Properties

• The advertised flow rate should not be assumed to remain constant when the pump is working against significant outlet resistance.
• Fluid viscosity, tubing characteristics, pressure, and temperature can all influence performance.

Correct Tubing Selection

• Using tubing with incorrect dimensions can result in poor flow, leakage, excessive wear, or improper operation.
• For peristaltic pumps, tubing dimensions are therefore part of the pump system rather than merely an accessory.

8. Micro Peristaltic Pump Electrical Requirements

• The NKP pumps use DC brushed motors, so electrical polarity and supply voltage should be considered before connecting the pump.
• The five models covered in this article have different nominal voltages.
• A 24V model should be supplied from an appropriate 24V DC source, while a 12V or 6V model requires its corresponding supply voltage.
• Applying an incorrect voltage can result in excessive motor speed, overheating, reduced lifetime, or motor damage.

The approximate electrical relationship between power, voltage, and current is: P = V × I

where:

• P = electrical power in watts
• V = voltage in volts
• I = current in amperes

For a 5W pump operating at 24V, the theoretical current corresponding to 5W is approximately:  I = 5 / 24 ≈ 0.21 A

For a 5W pump operating at 12V: I = 5 / 12 ≈ 0.42 A

For a 5W pump operating at 6V: I = 5 / 6 ≈ 0.83 A

These calculations are useful for understanding the electrical scale, but the actual current drawn by a brushed motor varies with load and operating conditions.

Therefore, the power supply and control circuit should be selected with suitable current margin.

9. NKP Micro Peristaltic Pump Models

The NKP family includes several versions that share a similar mechanical concept but differ in voltage, tubing size, and flow rate.

For the five distinct models relevant to this article, the main specifications can be summarized as follows.

The published specifications for the NKP models and the Makers Electronics product listings support these model-specific values.

Important note:

• The original model list for this article contains NKP-DA-S06B twice.
• The second occurrence has been treated as NKP-DE-S06B because that is the distinct 6V S06B model currently listed by Makers Electronics.

10. NKP-DA-S04B 24V 10 mL/min 5W

The NKP-DA-S04B is a compact 24V DC micro peristaltic pump designed for relatively low flow applications.

Its principal specifications include:

• Rated voltage: 24VDC
• Power: 5W
• Flow rate: ≥10 mL/min
• Motor: DC brushed motor
• Tube material: Silicone
• Tube size: approximately 1 × 3mm
• Number of rotors: 3
• Reference noise level: below 50 dB
• Approximate weight: 100 g

The smaller S04 tubing configuration is associated with the lower flow rate of approximately 10 mL/min.

The 24V supply makes this model particularly convenient when the rest of the control system already uses a 24V DC power rail.

For example: it may be considered in automated dosing, liquid dispensing, small fluid-transfer systems, and experimental equipment where approximately 10 mL/min is appropriate.

11. NKP-DE-S04B 6V 10 mL/min 5W

The NKP-DE-S04B uses the same general S04 pump configuration but is designed around a 6V DC supply.

Its main specifications include:

• Rated voltage: 6VDC
• Power: 5W
• Flow rate: ≥10 mL/min
• Motor: DC brushed motor
• Tube material: Silicone
• Tube size: approximately 1 × 3mm
• Number of rotors: 3
• Reference noise level: below 50 dB
• Approximate weight: 100 g

The main practical difference between this model and the 24V NKP-DA-S04B is the required motor voltage.

The 6V version can therefore be useful in projects powered from low-voltage DC sources, provided the power supply can deliver the required current.

The Makers Electronics specifications also indicate that PWM can be used when speed control is required.

12. NKP-DA-S06B 24V 38 mL/min 5W

The NKP-DA-S06B is a higher-flow model compared with the S04 versions.

Its principal specifications include:

• Rated voltage: 24VDC
• Power: 5W
• Flow rate: ≥38 mL/min
• Motor: DC brushed motor
• Tube material: Silicone
• Tube size: approximately 2 × 4mm
• Number of rotors: 3
• Reference noise level: below 50 dB
• Approximate weight: 100 g

The larger S06 tubing configuration provides a substantially higher nominal flow rate than the S04 configuration.

This model is therefore more appropriate when the application requires a higher liquid-transfer rate while retaining the compact form factor of the NKP family.

13. NKP-DE-S06B 6V 36 mL/min 5W

The NKP-DE-S06B is the 6V version of the S06 configuration.

Its main specifications include:

• Rated voltage: 6VDC
• Power: 5W
• Flow rate: ≥36 mL/min
• Motor: DC brushed motor
• Tube material: Silicone
• Tube size: approximately 2 × 4mm
• Number of rotors: 3
• Reference noise level: below 50 dB
• Approximate weight: 100 g

The Makers Electronics specification lists a flow rate of at least 36 mL/min and a 6V rated voltage.

This model can be considered when a project requires the higher flow associated with S06 tubing but operates from a lower-voltage DC supply.

Because the pump uses a 6V motor at 5W, the current requirement can be significant compared with the 12V and 24V versions. The power supply and switching circuit should therefore be selected accordingly.

14. NKP-DC-S06B 12V 37 mL/min 5W

The NKP-DC-S06B is the 12V version of the S06 configuration.

Its principal specifications include:

• Rated voltage: 12V DC
• Power: 5W
• Flow rate: ≥37 mL/min
• Motor: DC brushed motor
• Tube material: Silicone
• Tube size: approximately 2 × 4mm
• Number of rotors: 3
• Reference noise level: below 50 dB
• Approximate weight: 100 g

Makers Electronics specifies a flow rate of up to approximately 37 mL/min for this 12V model. The product information also describes reversible rotation and PWM-based speed control as possible control approaches.

The 12V supply requirement makes this model convenient for many embedded systems because 12V DC is commonly available in automation, robotics, automotive-related electronics, and laboratory projects.

15. How to Select the Right NKP Pump

Selecting an NKP pump should begin with the electrical requirements and the required liquid flow.

Start With the Available Supply Voltage

If the project already has a suitable 24V supply, the 24V models are natural candidates.

• For a 12V system, the NKP-DC-S06B is the corresponding S06 model in this group.
• For a 6V system, the NKP-DE-S04B and NKP-DE-S06B can be considered.
• The pump should not simply be connected to the closest available voltage. The rated voltage of the motor must be respected.

Determine the Required Flow Rate

• For approximately 10 mL/min, the S04 models are appropriate candidates.
• For approximately 36–38 mL/min, the S06 models provide the higher nominal flow range.
• The actual required flow should be determined from the application rather than selecting the pump solely from its maximum published flow value.

Check the Tubing

• The tubing must match the pump head.
• The S04 configuration uses approximately 1 × 3 mm tubing, while the S06 configuration uses approximately 2 × 4 mm tubing.
• The material must also be chemically compatible with the liquid being pumped.

Consider Operating Time

• If the pump will operate continuously, tube life becomes an important design consideration.
• The NKP specifications list approximately 200 hours of pump-tube life and approximately 800 hours of motor life for the referenced models. These figures should be regarded as manufacturer/reference specifications rather than a guarantee for every application.

Consider Speed Control

If variable flow is required, motor-speed control can be considered.

• The Makers Electronics product documentation suggests PWM for speed control.
• However, changing motor speed does not automatically guarantee a perfectly proportional or calibrated flow rate. For accurate dosing, the actual delivered volume should be measured and the system calibrated.

16. Applications of Micro Peristaltic Pumps

Micro peristaltic pumps can be used in many systems where relatively small quantities of liquid need to be moved or dispensed.

Typical applications include:

• Automatic liquid dispensers
• Soap and sanitizer dispensing systems
• Small dosing systems
• Laboratory equipment
• Liquid-transfer systems
• Chemical dosing prototypes
• Robotics projects
• Fluid-circulation systems
• Automatic irrigation prototypes
• Educational fluid-control projects
• DIY automation systems
• Liquid-based experimental equipment

When selecting an application, however, the chemical compatibility of the tubing, required flow, pressure, temperature, operating time, and required accuracy should all be checked.

17. Installation, Control, and Maintenance

Install the Tube Correctly

• Place the flexible tube evenly inside the pump head.
• Avoid sharp bends, twisting, excessive stretching, or incorrect tube positioning.
• Incorrect tube installation can affect flow and accelerate tube wear.

Prime the Pump

• Before normal operation, allow liquid to fill the tubing and remove trapped air.
• Although peristaltic pumps are self-priming, deliberate priming can improve the consistency of the initial flow and reduce air-related dosing errors.

Use an Appropriate Power Supply

• Use a regulated DC supply with the correct nominal voltage.
• The supply should also have sufficient current capacity, particularly for the 6V versions.

Control the Motor Carefully

• A simple switch can be used for basic on/off operation.
• For automated systems, a suitable transistor or motor-driver circuit can be used to switch the DC motor.
• PWM can be used for speed control where appropriate, but the relationship between PWM duty cycle and actual liquid flow should be experimentally calibrated for the specific system.

Replace Worn Tubing

Because the tubing is repeatedly compressed, it is normally the component most directly exposed to mechanical fatigue.

Inspect the tube for:

• Cracks
• Permanent deformation
• Flattened sections
• Leakage
• Reduced flow
• Slippage
• Loss of elasticity

Replacing worn tubing can restore reliable pump operation.

Calibrate for Accurate Dosing

• If the pump is being used for dosing rather than simple liquid transfer, do not rely solely on the nominal mL/min specification.
• Run the pump for a known period and measure the actual delivered volume.

For example:  Flow Rate = Delivered Volume / Operating Time

If 50 mL is collected during a 100-second test:

100 seconds = 1.667 minutes

Therefore:  Flow Rate ≈ 50 / 1.667 ≈ 30 mL/min

• This measured value can then be used by the controller for more accurate dosing.
• Calibration is especially important because tubing condition, pressure, fluid properties, and motor-speed variation can affect the actual flow.

18. Frequently Asked Questions

What is a micro peristaltic pump?

A micro peristaltic pump is a compact positive-displacement pump that moves liquid by compressing and releasing a flexible tube with rotating rollers.

Does the liquid contact the motor?

Normally, no. In a peristaltic design, the liquid remains inside the flexible pump tube, while the motor and rollers operate outside the liquid path.

What is the difference between the S04 and S06 NKP models?

The primary difference relevant to these models is the tubing configuration and resulting nominal flow rate.

The S04 models use approximately 1 × 3 mm tubing and provide approximately 10 mL/min, while the S06 models use approximately 2 × 4 mm tubing and provide approximately 36–38 mL/min depending on the motor/version.

Which NKP model uses 12V?

The NKP-DC-S06B is the 12V model discussed in this article and is specified at approximately 37 mL/min and 5W.

Which NKP models use 24V?

The NKP-DA-S04B is a 24V, approximately 10 mL/min model, while the NKP-DA-S06B is a 24V, approximately 38 mL/min model.

Which NKP models use 6V?

The NKP-DE-S04B is the 6V S04 model with approximately 10 mL/min flow, while the NKP-DE-S06B is the 6V S06 model with approximately 36 mL/min flow.

Can a peristaltic pump run in reverse?

Yes. The NKP product information states that the motor rotation direction can be changed through control.

Can the pump flow rate be controlled?

The motor speed can be controlled, and the product information suggests PWM for speed control. However, actual liquid flow should be calibrated because flow is affected by tubing, fluid properties, pressure, and other operating conditions.

Does a peristaltic pump need priming?

Peristaltic pumps are generally self-priming, but intentionally priming the tubing can help remove trapped air and establish a more consistent initial flow.

How long does the pump tube last?

The NKP product specifications list approximately 200 hours of tube life for the referenced models. Actual life depends on operating conditions, fluid characteristics, compression, temperature, and operating time.

19. Conclusion

A Micro Peristaltic Pump is a practical solution for moving and dispensing relatively small quantities of liquid while keeping the pumped liquid inside a flexible tube.

Its operating principle is simple: rotating rollers repeatedly compress the tube, move liquid forward, and allow the tube to recover behind the roller. This provides a compact positive-displacement pumping mechanism with useful characteristics for dosing, dispensing, laboratory equipment, robotics, and maker projects.

The NKP family provides several options for different electrical systems and flow requirements. The S04 models provide approximately 10 mL/min, while the S06 models provide approximately 36–38 mL/min depending on the voltage and model.

For an electronics project, selecting the correct NKP pump should be based on several factors rather than voltage alone:

• Required flow rate
• Available DC supply voltage
• Tubing size and material
• Fluid compatibility
• Operating pressure
• Required operating time
• Desired control method
• Required dosing accuracy

For simple liquid transfer, the nominal flow specification may be sufficient for initial selection. For accurate dosing, however, the final system should always be calibrated using the actual tubing, liquid, pressure, and operating conditions.

Understanding these factors allows hobbyists, students, makers, and engineers to use micro peristaltic pumps more effectively and to select the appropriate NKP model for their specific application.