The Peristaltic Pump: Principles and Components

What Is a Peristaltic Pump?

From a professional perspective, a peristaltic pump is a type of positive displacement volumetric pump. Its working principle is based on the "periodic compression and rebound of a flexible tube":

The driver provides power to drive the rotation of the rotor (equipped with multiple rollers) inside the pump head. As the rotor rotates, the rollers continuously compress the elastic tube in the pump head, forming "temporary sealed chambers" inside the tube. As the rollers roll forward, these sealed chambers move along the fluid delivery direction, pushing the fluid in the tube toward the outlet. When a roller moves away from a section of the tube, the tube rebounds due to its own elasticity, restoring the inner cavity volume and drawing in new fluid from the inlet. This cycle repeats to achieve continuous, one-way fluid delivery.

Still not quite getting it? Let’s think of a common life action: pinch a straw with your finger and push forward— the liquid in the straw will flow in the direction your finger moves. A peristaltic pump is essentially a "mechanical version of 'finger + straw'": it uses a motor-driven "roller" to replace the finger and an "elastic tube" to replace the straw. By continuously compressing the tube with the roller, the fluid is made to flow unidirectionally inside the tube.

Its core advantage, which also distinguishes it from centrifugal pumps and gear pumps, is that the fluid only comes into contact with the tube and no internal parts of the pump body. This means:

  • There is no need to worry about the fluid contaminating the pump body;
  • There is no need to worry about the pump body contaminating the fluid.

Three Core Components

Regardless of its size or application, a peristaltic pump relies on three core structures: the driver (power source), pump head (executing mechanism), and tubing (fluid delivery channel). The design parameters of these three components directly determine the pump’s flow accuracy, delivery stability, and service life. They are like a car’s "engine + transmission + tires"—none can be missing.

1. Driver

The core of the driver consists of a motor and a control module. Its main function is to provide stable power to the pump head and control the rotation speed of the rollers (rotation speed directly determines flow rate).

Motor Types

  • DC Brushed Motor: Low cost and high starting torque, suitable for simple civil fluid transfer (e.g., small aquarium water replenishment) and low-cost industrial chemical dosing—scenarios where precision and service life requirements are not high.
  • DC Brushless Motor (BLDC): Long service life, low noise, and good stability, suitable for precision fluid transfer in laboratories (e.g., chromatograph fluid supply) and small medical infusion devices—scenarios requiring low noise and long service life.
  • Stepper Motor: Extremely high speed control accuracy and no cumulative error, suitable for quantitative pipetting of laboratory samples and small-volume filling of food (e.g., 5mL essence filling)—scenarios with strict requirements for flow accuracy.
  • AC Motor: High output power and compatible with large flow rates, suitable for large-diameter chemical dosing in sewage treatment plants and large-flow nutrient solution delivery in agriculture—industrial scenarios requiring high flow rates and high pressure.

Control Modes

  • Manual Control: Adjust rotation speed via knobs or buttons, or control on/off with an optional foot pedal. Simple to operate, suitable for independent operation of a single pump.
  • Analog Control: Receives signals such as 0-5V/4-20mA, and can be linked with PLC (Programmable Logic Controller) or DCS (Distributed Control System).
  • Digital Control: Supports protocols like RS232/RS485/Modbus, enabling remote setting of flow rates and reading of operational data.

2. Pump Head

The pump head is the component that directly contacts the tubing and squeezes the fluid; it is also key to influencing "flow stability" and "tubing service life". For beginners, focus on three design aspects when evaluating pump heads:

Number of Rollers

Determines the degree of flow fluctuation. More rollers mean higher frequency of tubing compression and more stable flow (e.g., a 10-roller pump head reduces flow fluctuation by 30% compared to a 6-roller one). However, more rollers also accelerate tubing wear, shortening its service life by 10%-20%.

Compression Mechanism

The compression amount of the tubing must be precisely controlled: insufficient compression causes "insufficient suction lift and leakage", while excessive compression accelerates tubing aging. The mainstream compression methods in the industry are divided into two types:

  •  Manual Compression: Adjust the position of the pressure block via a knob to set the compression amount. Suitable for scenarios with fixed tubing specifications and low usage frequency (e.g., temporary laboratory experiments).
  • Automatic Pressure Compensation Mechanism: Achieves dynamic pressure compensation via springs or air cylinders. When the tubing thins due to wear, the pressure block automatically adjusts to maintain a constant compression amount. Suitable for 24/7 continuous operation scenarios (e.g., food filling lines, industrial chemical dosing systems) and can extend tubing service life.

Material

The pump head material should be selected based on the characteristics of the fluid being transferred (corrosiveness, temperature) and environmental requirements:

  • Engineering Plastic (PP/ABS) Pump Head: Lightweight (40% lighter than aluminum alloy), corrosion-resistant (suitable for transferring weak acids and alkalis), and low cost. Ideal for portable equipment (e.g., outdoor sampling pumps) but has poor high-temperature resistance.
  • Aluminum Alloy Pump Head: High strength and good heat dissipation, suitable for transferring high-viscosity fluids (e.g., syrup, lubricating oil). However, it is heavy and has a higher cost.
  • Stainless Steel Pump Head: Superior corrosion resistance, suitable for pharmaceutical and semiconductor scenarios, but with a higher cost (higher than aluminum alloy).

3. Tubing

Tubing is the "consumable" of a peristaltic pump. Choosing the right tubing prevents leakage and contamination, while also reducing replacement frequency (lowering costs). For beginners, the core of tubing selection is to match the "fluid characteristics" with the corresponding material:
  • Silicone Tubing: Cost-effective with good elasticity and easy installation, suitable for transferring "water, neutral reagents, and food-grade fluids" (e.g., beverages, clean water). However, it has obvious drawbacks: not oil-resistant, not resistant to strong acids/alkalis (e.g., sulfuric acid, alcohol), and hardens with aging after long-term use.
  • Fluororubber Tubing (FKM): The "king of corrosion resistance", capable of transferring sulfuric acid, hydrochloric acid, and organic solvents (e.g., methanol, acetone). Suitable for chemical and environmental protection scenarios, but has poor elasticity and high cost (3-5 times that of silicone tubing).
  • Food-Grade Silicone Tubing: Has FDA certification (compared to regular silicone tubing) and contains no plasticizers. Suitable for transferring fluids in direct contact with food (e.g., sauces, yogurt, cooking oil). Note: Choose "high-temperature resistant models" (e.g., resistant to 120°C) for easy cleaning and disinfection.
  • Teflon Tubing (PTFE): Excellent resistance to both high/low temperatures (-200°C to 260°C) and corrosion (can withstand aqua regia). However, it is hard and has poor elasticity, requiring matching with a "high-pressure pump head". It is generally only used in special scenarios (e.g., fluid supply for high-temperature reaction kettles).

Tip

The "inner diameter and wall thickness" of the tubing directly affect the flow rate:
  • At the same rotation speed, the flow rate is proportional to the square of the tubing’s inner diameter (e.g., the flow rate of tubing with an 8mm inner diameter is 4 times that of tubing with a 4mm inner diameter).
  • Wall thickness affects compression resistance: thicker walls (e.g., 3mm vs. 2mm) provide better anti-aging performance, but must match the pump head’s compression design (to avoid insufficient compression).
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