Peristaltic Pump Knowledge Guide

What is a Peristaltic Pump?

A peristaltic pump consists of three parts: the drive, the pump head, and the tubing. The fluid is isolated within the pump tubing, which can be quickly replaced. The fluid can move reversibly, and the pump can operate dry, resulting in low maintenance costs. These features constitute the main competitive advantages of peristaltic pumps.

Working Principle of Peristaltic Pumps

A peristaltic pump operates by squeezing a fluid-filled tube, much like squeezing a tube with fingers, where the fluid moves forward as the fingers slide forward. The peristaltic pump operates on a similar principle but uses rollers instead of fingers. The fluid is pumped by alternately squeezing and releasing the elastic delivery tubing of the pump. Similar to squeezing a tube with two fingers, negative pressure forms inside the tube as the fingers move, causing the liquid to flow.

In a peristaltic pump, a "pillow" of fluid is formed in the section of tubing between two rotating rollers. The volume of the "pillow" depends on the inner diameter of the tubing and the geometric characteristics of the rotor. The flow rate depends on the speed of the pump head, the size of the "pillow," and the number of "pillows" produced by the rotor per revolution. The size of the "pillow" is generally constant (except when pumping highly viscous fluids).

Compared to pumps with the same rotor diameter, pumps that produce larger "pillows" also deliver larger volumes of fluid per revolution but exhibit greater pulsation. This is similar to the behavior of diaphragm pumps. Pumps that produce smaller "pillows" deliver smaller volumes of fluid per revolution, and the rapid, continuous formation of small "pillows" results in smoother fluid flow, similar to gear pump operation.

What are the Advantages of Peristaltic Pumps?

• Non-contamination: Fluid only contacts the pump tubing, not the pump body.

• High precision: High repeatability and stability.

• Low shear force: Ideal for conveying shear-sensitive and highly erosive fluids.

• Excellent sealing: Good self-priming ability, can run dry, and prevent backflow.

• Simple maintenance: No valves or seals required. 

• Dual-directional equal flow delivery capability; no damage to any pump components during liquid-free operation; can achieve up to 98% vacuum; no valves, mechanical seals, or packing seals means no factors causing leakage and maintenance; easy transport of solid, liquid, or gas-liquid mixtures; allows solid particles in the fluid to reach up to 40% of the inner diameter of the tubing; can convey various materials with grinding, corrosion, and oxygen-sensitive characteristics, as well as various food products; only the tubing needs replacement, which is extremely simple; the conveyed product does not come into contact with any components other than the tubing.

How to Determine a Peristaltic Pump?

1)Pressure limitations: Using flexible tubing can limit the pressure tolerance.

2)Pulsating flow during pump operation can be addressed by:

a) Increasing the number of rollers, which decreases flow rate.

b) Using a pulse suppressor: A pulse suppressor is a simple positioning container that works by absorbing pulses as the pulsating flow enters the container and the airbag on the liquid side collapses to absorb the pulses, thus smoothing the flow out of the pulse suppressor.

3)Flow rate may decay over time due to tubing wear.

4)The pump's outlet pressure has certain limitations, usually not exceeding 0.3 MPa, typically between 0.1-0.2 MPa.

Applications of Peristaltic Pumps

Peristaltic pumps find applications in various industries, including:

• Chemical Industry

• Mining and Metallurgical Industry

• Paper Industry

• Paint and Coatings Industry

• Food Industry

• Ceramic Industry

• Petroleum Industry

• Water Treatment Industry

• Pharmaceutical Industry

• Medical Devices Industry

In the pharmaceutical industry, peristaltic pumps are mainly used for drug coating granulation and pharmaceutical filling. Spray drying granulators, also known as drying granulators and fluidized bed granulators, are machines used to coat various granular soluble materials with special sugar coatings, which dry to form granules. These granulators themselves serve as specific drying heat sources, capable of evaporating moisture. However, the relationship between moisture evaporation and granule formation is dynamic, thus requiring precise control of the amount of liquid and moisture injected to ensure the granules maintain a certain humidity, facilitating their perfect formation.

Classification of Peristaltic Pumps

Peristaltic pumps are classified based on their operation and usage:

• Speed-adjustable Peristaltic Pump: Equipped with basic control functions such as speed display, start/stop, direction, speed adjustment, filling/venting, power-off memory, external control input, etc.

• Flow-rate Peristaltic Pump: In addition to basic functions, it also includes flow rate display, flow rate correction, communication, etc.

• Distribution-type Peristaltic Pump: In addition to basic control functions, it adds functions such as flow rate display, flow rate correction, communication, liquid distribution, suction, output control, etc.

• Customized (OEM) Peristaltic Pump: Equipped with a range of peristaltic pump heads with different flow rate ranges, customers can design different peristaltic pump drive circuits according to their equipment requirements for use.

Components of Peristaltic Pump System

A peristaltic pump system consists of three parts: peristaltic pump driver, peristaltic pump head, and peristaltic pump tubing.

Components of Peristaltic Pump System

A peristaltic pump system consists of three parts: peristaltic pump driver, peristaltic pump head, and peristaltic pump tubing.

Tubing Selection

1）Criteria for peristaltic pump tubing include:

Elasticity: The tubing should quickly recover its shape after radial compression.

Wear resistance

Pressure resistance

Leak-proof (good air tightness)

Low adsorption, good temperature resistance, resistance to aging, no swelling, corrosion resistance, low precipitation, etc.

2)Pump Head Selection

Considerations for pump head selection include:

Single or multi-channel fluid delivery

Ease of tubing replacement

Ease of securing tubing

3)Roller selection: 6-roller structure yields slightly higher flow rates; 10-roller structure results in smaller fluid pulsation amplitude

Trigger structure convenience and ease of opening the card

4)Driver Selection

Considerations for driver selection include:

Need for flow control

Need for liquid distribution

Range of flow rates

Overall construction and ease of operation

Flow accuracy, liquid accuracy

Special requirements: protection level, explosion-proof level, etc.

External control requirements: equipment matching, operating mode, such as RS232, RS485 communication, 0-5V external speed control, pulse speed control, etc.

What Should Be Considered for Daily Maintenance of Peristaltic Pumps?

During daily use, it's advisable to replace tubing after prolonged use to prevent silicone tube rupture. This prevents corrosive liquids from flowing into the roller inside the pump head through the tubing, potentially causing corrosion in the roller gaps. If corrosive liquids are used, select imported tubing of corresponding materials to prevent pump damage.