What is a centrifugal fan? Complete guide to working principle, types and uses

A centrifugal fan is not just a component. It plays a central role in determining the efficiency, reliability, and safety of industrial processes.

This guide provides a complete, engineering-driven overview of centrifugal fans: how they work, how they are designed, where they are used, and how to select the right solution for a specific process.

On this page:

• What is a centrifugal fan? 
• Centrifugal fan working principle
• Key characteristics and dimensions
• Centrifugal fan uses: applications across industries
• Efficiency and performance curve
• Types of centrifugal fans and technical specifications
• Centrifugal fan installation considerations
• CBI group: leading centrifugal fan suppliers

What is a centrifugal fan?

A centrifugal fan is an industrial fan that draws air into a rotating impeller, which transfers energy to the fluid by increasing its velocity and pressure. Air is moved radially thanks to centrifugal force generated by the impeller, accelerating it outward and discharging the flow typically at 90° to the inlet direction. 

It is used in industrial processes where the conveyed fluid may carry dust, operate at high temperatures, or contain aggressive gases. This radial airflow configuration makes centrifugal fans particularly effective for applications requiring medium to high static pressure and reliable performance in harsh conditions.

When evaluating airflow solutions, it is essential to understand the technical differences between an axial fan vs centrifugal fan, as the choice depends entirely on the system's pressure and volume requirements. Every CBI centrifugal fan series is engineered to meet these specific operating requirements with configurable designs.

Centrifugal fan working principle

Understanding how a centrifugal fan works starts with its three main components: the impeller, the casing (scroll or volute), and the inlet.

• Inlet: air enters axially, drawn in by the low-pressure zone created at the impeller eye as it rotates.

• Impeller: the rotating blades accelerate the air radially outward, imparting kinetic energy through centrifugal force.

• Volute casing: this component collects the high-velocity air and progressively slows it down, converting velocity pressure into static pressure.

• Discharge: air is expelled at 90° to the inlet, at significantly higher pressure than at entry.

Get more info for an in-depth look at how aerodynamic parameters affect performance.

Key characteristics and dimensions

Centrifugal fans are defined by high-pressure performance and stable operation under variable loads. A common technical query concerns centrifugal fan dimensions: these are not fixed but are strictly related to the impeller diameter and the specific series. CBI fans range from small units (500 mm) to large-scale industrial installations exceeding 2,450 mm in diameter. 

Main features:

• Radial discharge: air or gas is expelled outward at 90°, allowing effective static pressure generation;

• Stable operation: maintains consistent behaviour under variable load conditions;

• Heavy-duty construction: built for environments with dust, high temperatures, or corrosive substances;

• Wide temperature range: depending on the series, CBI centrifugal fans are rated for operation up to 300 °C, and up to 650 °C in specific high-temperature series (RT).

Centrifugal fans are used wherever air or gas must be conveyed or extracted under demanding conditions. For a detailed breakdown by sector, see: what a centrifugal fan is used for.

Efficiency and performance curve

The efficiency of a centrifugal fan describes how effectively it converts shaft power into useful work on the fluid. Typical centrifugal fan efficiency at the Best Efficiency Point (BEP) ranges from approximately 70% to 85% for backward-inclined and airfoil blade designs.

•  Flow rate (m³/h): volume of air moved per hour.

•  Static pressure (Pa): resistance the fan can overcome.

•  Best Efficiency Point (BEP): operating away from the BEP increases energy consumption and introduces unnecessary mechanical stress.

Types of centrifugal fans and technical specifications

CBI Group manufactures different types of centrifugal fans, each with unique specifications.

Comparison table
Note: BIF = backward inclined flat; BIC = backward inclined curved.

Centrifugal fan installation considerations

Correct installation is as important as correct selection. The principal considerations are covered in:

•  Inlet conditions: disturbed or swirling inlet flow significantly reduces performance. Straight duct runs of at least 2–3 diameters upstream are generally recommended.

•  Vibration isolation: anti-vibration mounts or flexible connections prevent structural transmission of fan-generated vibration.

•  Alignment (belt-driven units): misaligned drives lead to premature bearing and belt failure.

•  Balancing: impellers must be dynamically balanced to the appropriate grade before installation and re-checked after any repair involving material removal.

•  Commissioning checks: rotation direction, motor current at full flow, bearing temperature, and vibration levels should be verified at first start-up.

CBI Group provides complete turnkey installation assistance for all fan types and related accessories, ensuring correct execution on site.

CBI Group: leading centrifugal fan suppliers

Founded in 1963, CBI Group is a leading manufacturer of industrial ventilation solutions. As one of the most reliable centrifugal fan suppliers globally, we operate 5 production plants, producing approximately 23,000 fans per year.

All facilities operate under ISO 9001 and ISO 14001 certification, and for special executions, only on request, CBI manufactures products compliant with ATEX guidelines.

Our R&D division uses advanced CFD and FEM analysis to optimize aeraulic and structural performance, ensuring that every industrial centrifugal fan we deliver meets the highest standards of the modern industry.