A High Pressure Centrifugal Blower is a type of fan which generates high pressure and volume due to its technical design. It differs from the axial fan in that the direction of air movement through it is different during operation. A normal centrifugal fan is made of sheet metal. A High Pressure Centrifugal Blower is different from a normal centrifugal fan, usually made from strong cast metal. Centrifugal Blowers consist of a specially designed impeller, housing, a shaft and a drive.
The impeller is a type of rotor, specially constructed with ribs and blades to force air toward the circumference of the wheel when it spins. The housing has a built-in inlet and outlet, and contains the rotating impeller. Housings keep a regulated pressure range due to their constant volume. The shaft is the axis about which the impeller rotates. It connects to the drive to transfer torque or rotation. The drive provides the rotating force to the impeller. The shaft can be driven by an electric or diesel motor, a belt connected to a rotating device or a coupling. Many high pressure applications use internal combustion engines to generate the torque required. Efficient Diesel engines with high compression ratios are usually perfect as they are very efficient and provide a strong torque or rotating force compared to the power input. Basically, a centrifugal blower works by sucking air at the eye of the impeller wheel inlet and expelling at the circumference’s outlet at 90 degrees to the direction of the intake air.
Blowers, Not Fans
They are labelled as blowers and not fans because they serve the purpose of overcoming resistances such as solid particles and restrictions in the air flow. Fans generally only provide ventilation and air or gas movement. High Pressure Centrifugal Blowers are rarely used for human ventilation unless the air is being transported over a considerable distance to lower the pressure by delivery to the space.
These applications can be seen in large HVAC systems where there is a lot of ducting and many spaces to serve. The CFM (cubic feet per minute) requirements at each destination of the ducts must be calculated to determine the pressure at which the air will exit the system after overcoming the resistances. The area of the outlet will vary depending on the distance the air had to travel from the blower. Once the air travels and expands, the pressure will be lowered. High Pressure Centrifugal Blowers create unfavourable environments for living creatures due to high pressures at the exact outlet of the blower. For this reason, custom blowers should be designed for each specific application.
Blower Impeller Types
The impellers on High Pressure Centrifugal Blowers have specifically designed blades for varying conditions. These types are Backward-Arched, Radial and Forward-Arched Radial tip.
Backward-Arched blades are aerodynamically designed to prevent dust or particle build-up on the blade during operation. They curve away from the direction of rotation as they extend from the eye of the impeller. They are strong and are perfect for high pressure applications.
Radial blades extend straight out from the eye of the impeller and are the simplest form. They are used for high pressure applications with nominal efficiency.
Forward-Arched Radial tip blades are arched towards the direction of the flow, and approach the circumference of the impeller at a 90 degree angle. This design provides high pressure applications without causing particles and debris to be trapped in the middle of the impeller.
High Pressure Blower Applications
These types of fans are well suited for corrosive, unclean air and exhaust fumes. This is why it is so important that the blades stay clean and operate at their full capability. High Pressure housings can be designed to split to facilitate easy access to the impeller for cleaning. These High pressure housings are made from stainless steel or alloys and can handle up to 20,000 Pascals of pressure.
High Pressure Centrifugal Blowers are considered as heavy machinery and need to be tailor made for each application. The margin for error is small and the relevant professionals should be consulted. Custom Fans of Australia will be able to provide engineering information with numbers and values to determine how the high pressure centrifugal blower system will perform in your operation.