Centrifugal Blowers: Your Comprehensive Guide

When working in confined spaces, it’s important to prioritise safety and not take any risks. Especially, when you’re working in a hazardous environment. In such conditions, you need to have safety certificates, like the one from OSHA 1910.146. According to OSHA, you should have centrifugal blowers / fans at your convenience. They keep the air fresh and provide a safe breathing environment.

Understanding Centrifugal Blowers

A mechanical device called a centrifugal blower or centrifugal fan is designed to move air or other gases from the centre of rotation in the outer direction. Unlike axial fans that direct airflow parallel to the fan’s axis, centrifugal blowers channel air at a right angle to the intake. This design generates high-velocity airflow, which is highly suitable for applications that require both pressure and airflow, such as air conditioning units, ventilation systems, and industrial processes.

How do High-Velocity Centrifugal Blowers / Fans Work

The operation of a high-velocity centrifugal fan relies heavily on its impeller.

Impeller Design And Centrifugal Force

At the heart of a centrifugal blower / fan lies its impeller. Comprised of curved blades arranged around a central hub, the impeller is the key component. Connected to a rotating shaft driven by an engine or motor (usually electric). As the motor spins the shaft, the impeller blades also rotate rapidly.

Rotation of the impeller generates centrifugal force. Therefore, it pushes air molecules outward from the centre of rotation toward the edges of the impeller. This force creates a pressure gradient, causing the air to move outward radially. The speed of the impeller directly influences the amount of air pressure produced.

Air Inlet And Flow

Air enters the centrifugal fan through the central air inlet of the impeller. As the impeller spins, creating centrifugal force, air is drawn into it from its surroundings. The impeller then propels the air outward due to the centrifugal force acting upon it.

Diffuser Or Scroll

After leaving the impeller, the air flows into a diffuser or scroll housing. This housing guides the high-velocity, low-pressure air from the impeller into a higher-pressure, lower-velocity airflow. Also, the diffuser slows down the air gradually, converting the kinetic energy gained from the impeller into static pressure.

Velocity Profile And Outlet

The airflow within a centrifugal fan exhibits a velocity profile. This means that air at the outlet’s outer edge has a higher velocity compared to air nearer to the centre. This profile results from varying centrifugal forces acting on the air particles as they travel from the impeller to the outlet.

At the outlet, the airflow is directed at a different angle from the inlet, typically exiting at a 90° angle perpendicular to the inlet. Also, this angular output allows the airflow to maintain high velocity while sustaining high pressure. This distinct airflow direction makes centrifugal fans suitable for applications requiring specific airflow patterns.

Types of Centrifugal Fans

Forward Curved Centrifugal Fans

Centrifugal fans that come equipped with curved blades inclined forward are known as forward-curved fans. They are ideal for use in low-pressure applications such as HVAC systems, air purifiers and dust collectors. So, they provide significant airflow at low pressures. Additionally, they are not too noisy, making them perfect for places where noise is a concern.

Backward Curved Centrifugal Fans

Centrifugal fans with backward-curved blades are designed to generate higher pressure compared to forward-curved fans. They are highly efficient in moving air and are ideal for high-pressure applications. Also, they are suitable for industrial ventilation systems, air conditioning and refrigeration syste

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Radial Centrifugal Fans

Radial centrifugal fans are used in industrial settings. Their purpose is to create high-pressure airflow in a radial direction. They are suitable for a variety of domains, including industrial exhaust systems, material handling and pneumatic conveying. Also, they use centrifugal force to generate a high-velocity stream of air. The stream of air is then directed in a radial direction. This makes them ideal for applications where high-pressure airflow is required. Moreover, they can move large volumes of air quickly and efficiently.

Aerofoil Centrifugal Fans

Centrifugal fans are designed with a series of blades that resemble the aerofoils of an aircraft’s wing. These fans are highly efficient at moving large volumes of air at high pressures due to their unique design. The blades of the fan create a spinning motion Continue Reading...