Centrifugal Fan Impeller: What Is It And How It Works

What Is A Centrifugal Fan Impeller?

An impeller is a core part of a centrifugal fan as it directs the movement of air through the ventilation system. A central hub mounts a series of blades where the motor causes the impeller to rotate at high speed rate. 

The rotational movement of the blades draws air into the fan and pushes it outwards, perpendicular to the intake direction, using the centrifugal force generated by the movement of the impeller. 

The design of the impeller contributes directly to the overall performance of the centrifugal fan. In fact, it influences the volume of air it can move, the ability to increase pressure due to the angle of its blades, and energy consumption. 

It is through the impeller that rotational energy is converted into kinetic energy, which determines the fan’s ventilation, cooling, or extraction capacity in a range of industries.

How Does It Work?

A fan impeller utilises centrifugal force and fluid dynamics. As the impeller rotates, air is pulled in by several blades arranged around a central axis. Air is then expelled by the impeller’s blades as motion causes an object to move away from the centre of rotation. 

The outward movement from the centre of the impeller is subjected to a pressure increase and an acceleration because energy is transferred from the rotating blades. Air is directed into a casing surrounding the impeller. Here, kinetic energy is transformed into pressure energy as the volume of the casing expands. This is what enables the fan to move against ductwork or other systems opposing a certain resistance. 

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How To Effectively Control A Centrifugal Fan Impeller

A centrifugal fan impeller can be effectively controlled by monitoring the movement’s speed, the volume of air drawn in, and pressure. In order to do so, you can use some methods, such as: 

• Variable Frequency Drives, also known as VFDs. This can fine-tune the power supply of the motor, thereby controlling the impeller’s acceleration. By varying the impeller’s speed, it is possible to handle the amount of air displaced, and the pressure generated, ensuring the full efficiency of the fan.
  
  

• Integrating an airflow control device (dampers). In this case, the volume of air and pressure can be monitored within the ventilation system. These tools can be positioned at the fan inlet or outlet, allowing a better performance of the centrifugal fan. 

The centrifugal fan impellers by CBI Group

The CBI Group history dates back to the ‘60s. Since then, the company has been researching and developing new centrifugal fan solutions with different types of impellers to make every system more efficient and technologically advanced. Furthermore, each blower can be customised to be more suitable for specific applications. Let’s discover some CBI Group lines.

• The Ch Series features a radial blade and backwardly curved blades. This model is available both with direct and transmission arrangements. It is capable of handling airflows up to 300,000 m³/h, and it has been engineered to withstand temperatures up to 300 °C.

• The ChT Series escalates performance with options for airfoil or backwardly flat blades. It can achieve airflows up to 600,000 m³/h and pressures up to 5,000 Pa. This model is suitable for direct or transmission drive systems.

• The K Series offers versatility with backwardly flat or radial blades (open or closed). It supports airflows up to 400,000 m³/h in environments up to 300 °C.

• The Z Series is designed for demanding applications. With backwardly flat blades, it is capable of achieving airflows up to 400,000 m³/h and pressures up to 9,000 Pa.

• The EVO Series pushes the boundaries with its backwardly flat blades, crafted for temperatures up to 400 °C. This model delivers airflows up to 320,000 m³/h and pressures up to 12,000 Pa.

• The S Series focuses on high-pressure applications, with backwardly flat blades supporting airflows up to 200,000 m³/h and pressures reaching 25,000 Pa.

• The M Series balances airflow and pressure. It offers up to 250,000 m³/h and 20,000 Pa, designed for a wide range of industrial environments.

• The X Series maximizes airflow capabilities up to 500,000 m³/h and pressures up to 12,000 Pa, ensuring broad application coverage.

• The H Series caters to more specialized needs with backward curved or radial blades, suitable for airflows up to 10,000 m³/h.

• Lastly, the RT Series stands out for high-temperature applications. Its forwardly radial tip blades are engineered to handle up to 650 °C, airflows up to 700,000 m³/h, and pressures up to 12,000 Pa. It handles dirty gasses as well (high amounts of dust or debris

All series are customizable both in terms of performance and to operate at higher temperatures than those listed in the catalog.

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