A High Pressure Axial Fan is an air handling device which generates air movement and high pressures within the configuration or design of a normal axial fan. An axial fan is a fan which generates air movement parallel to the direction of the shaft or axis that the impeller is mounted on. Axial fans consist of an impeller, shaft, drive and housing. The impeller consists of blades which are designed for specific applications such as high speed, low speed, and higher pressures at low speeds or good heat dissipation at low speeds. Some impellers are even designed to handle corrosive gases and cooler temperatures.
Impeller Shapes
Some of the types or shapes of impeller blades are sickle shaped, aerofoil shaped, increasing depth shaped, uniform depth shaped and reversible direction aerofoil shaped. Axial Fans are not usually used to produce high pressures when they are installed. They are better suited for simple efficient air movement and low pressure applications.
Centrifugal designs are better for high pressure applications. Centrifugal fans and blowers generate higher pressures easier due to their design which naturally builds pressure. Centrifugal fans work by drawing air in at the eye of the impeller and expelling it at a 90 degree angle at the circumference of the rotor. This design ensures that resistances to the flow will not affect the function with back pressures. Centrifugal Fans can be fitted with the necessary blade or rib designs and housing to generate the specified or required air flow and pressure.
Axial Fans can be designed to obtain high pressures with static vanes placed strategically within the airway and specially designed impellers. A regular Axial Fan will not need a large distance between the impeller and the housing. The housing of a regular axial fan can be created with galvanized steel and is allowed to have considerable distances between the housing and blade, and leaks. This is due to the fact that regular axial fans just need to direct air movement.
High Pressure Axial Fans are Differences
High Pressure Axial fans, like the types that Custom Fans designs, are a different kettle of fish. These fans are generally tube axial shaped, and the housing has to be coated with thick steel or another tough metal for maximum strength. Housing design generally tells whether a fan will be easy to maintain or repair. Housings on high pressure axial fans should be split and bolted to give access to the motor, impeller or the vanes. The motor should be welded to the casing to stay put during peak operations, and the impeller should be specially designed and also coated. The impeller’s hub is large compared to a regular axial fan’s impeller, the blades are aero-foil shaped and they have a thick depth.
This means that the radial length of the blades on the impeller is shorter than on regular axial fans. Hot-rolled or galvanized steel is a great option for the impeller, and the blades can be fixed pitch or made to vary if the motor fails. The fan can be painted with a coating to protect them from corrosive gases. A great advantage of these types of high pressure fans is that the maintenance is easier due to convenient access and design of the blade, which does not tend to trap dust or other solid particles easily. In some applications, the motor can be mounted on the outside instead of in the airway. This provides a better aerodynamic design. Some High pressure axial fans are designed to handle a great amount of heat due to them being coated with heat resistant paint.
High Pressure Axial Fan Applications
High Pressure Axial Fans are great for applications such as mining and extreme HVAC cases where a centrifugal fan would not do. A centrifugal fan can be difficult to mount in certain positions due to the difference of air flow directions at the inlet and outlet of the housing. Axial fans are very easy to mount and do not require complicated ducting in most situations. A centrifugal fan or blower requires a smaller duct at the inlet than the outlet and has a perpendicular direction between each. High pressure Axial Fans should be engineered and custom built by professionals which have been in the industry for years. Careful vibration analysis and behavioral tests should be done on a High Pressure Axial Fan to ensure the smooth operation after installation.