Axial Versus Centrifugal Fans – Which is Right for You?
There are two different types of technologies uses for fans in domestic, commercial, and industrial environments. They vary in the way they transport air along the motor shaft. Axial-flow fans move air directly in a straight line along the axis, both on the intake and outlet side. The rotation of the blades propels the air but it does not change the direction of the airflow. Centrifugal fans, on the other hand, take in the air, move it at a 90° angle and blow it out in a different direction. This angle creates resistance and centrifugal force. The air passes through a multitude of closely aligned forward and backward-curved blades. These technological features transform part of the velocity energy into pressure energy.
Axial-Flow Fans Technology:
Linear, direct airflow through the impeller shaft
Ideal for ventilation in bathrooms, WCs, domestic kitchens
+ Generally easy to install
+ Basic models available at a low price
+ Requires little space for installation
+ Wide selection of shape, size, colour etc.
- Noise level increases with the rotation speed
- Limited pressure generation
Centrifugal Fan Technology
Blows off airflow at a 90° angle to the centre line
Ideal for connection to ventilation and filter systems
+ High pressure generation thanks to centrifugal force
+ High air circulation
+ Low-noise despite high rotation speed
+ Ventilation in long, winding ducts
- Requires adequate installation space for an angled shape
- Higher purchase price than basic axial-flow fans
The two types technologies have benefits and drawbacks that should be kept in mind when choosing a fan. Axial-flow fans are typically built into walls or windows. For example, they are often used for ventilation in bathrooms. Ceiling, desk, and portable fans are also axial fans. Fans of this type move a high amount of air without generating a strong pressure.
Centrifugal fans have two big differences compared to axial-flow fans. The inlet air is pushed with great force and against the natural resistance at a 90° by using the centrifugal force. The air passes through a multitude of closely-aligned forward and backward-curved blades. During this process part of the velocity energy is transformed into pressure energy. Thanks to this technology the outlet air can be channelled through long pipes and ventilation ducts without losing momentum or returning airflow.
The shape of the impellers should be matched to the place of installation. Blades that are curved backwards have proven great efficiency when exposed to high pressure, forward blades are better with low pressure. Straight blades prevent accumulation of particles due to extremely polluted air (special purpose).
Centrifugal fans are used wherever axial-flow fans fail to generate enough pressure. They are usually applied in domestic environments as part of a controlled indoor ventilation where the air passes through coarse and fine filters or even heat exchanger plates with ease. Most commercially available axial-flow fans however literally run out of steam when confronted with such intermediate parts.
Centrifugal Fan Applications
- Centralised ventilation systems in newly-built houses
- Connection to fume hoods and ventilation systems
- In systems with heat exchangers and filter boxes
- Commercial kitchens in cafeterias, restaurants, hotel industry
- Assembly halls, industrial facilities, and other large buildings
- Companies specialising in restoration, cleaning and manufacturing
- Areas with chemical storage and/or high fire danger e.g. gas station, garage, laboratory
- To speed drying of construction materials, pavement, carpet
- Prevention of mould in damp cellars, basements
Technical information for Centrifugal fans
The centrifugal fans in our range have protective housings made from high quality, double-coated, galvanised steel sheets. Some are even double-coated for even better durability. These premium materials and careful lacquering during the production process make the casings of our branded goods robust and resistant to scratches. This is important to ensure your fan will have a long service life. Non-corroding units are perfect for use in humid areas, locations with chemical vapour, and outdoors.
Interior fan components are made of resistant metal and are protected against outside elements. Our range offers many options, tailored to meet specific requirements. For example, we offer ball-bearing motors that are equipped with a self-cooling function to prevent overheating due to continuous operation. Thanks to innovative technology, our models consume little power and operate quietly, despite high revolution speeds.
Centrifugal fan speeds can be adjusted to current requirements. Many of our centrifugal fans include a controller to regulate the fan speed. We also sell controller units which can be purchased separately. Depending on the model, the speed is regulated by an included controller, otherwise a controller unit is usually available to be purchased separately. Generally, the fans can be mounted in a variety of positions and angles to facilitate installation and integration, even in smaller rooms. To keep the installation process simple, most of our centrifugal fans already have drill holes and flanges for connection to ventilation ducts. As the air is let out at a different angle than it is taken in, centrifugal fans sometimes require more installation space. There are a few special shapes for specific industrial environments, e.g. without a protective housing or with inlet ports on both sides. However, as these types are not part of the range, we shall not delve into this topic.
When comparing prices of axial-flow and centrifugal fans, it quickly becomes clear that axial-flow fans are less expensive. Keep in mind, however, that a one-time investment in a centrifugal fan will yield a ventilation system that will provide better energy efficiency and a more powerful airflow.
As mentioned above, centrifugal fans are ideal for integration in ventilation and air conditioning systems with filter boxes and units used for heat recovery. In newly built houses with a centralised air supply, a centrifugal fan is essential: only this unit is powerful enough to generate enough pressure to send air throughout the duct system so that the supply air can reach each area of the house. Centrifugal fans are found in domestic and professional environments alike, however, models for private households are usually smaller than industrial units.
The large versions of these high-performing appliances are primarily used in rooms with strong odours or steam (e.g. commercial kitchens with several stoves). Industrial sites where toxic vapour or explosive gas could be present also require power fan units. This is necessary both to ensure worker safety and to prevent vapours from creating other safety hazards.
On construction sites and many other industries, centrifugal fans are important tools for speed drying, whether it be paint, concrete or other materials, or to clear fumes from the work area. Portable units can be used to support dehumidification of carpets after cleaning or following a leak.
According to manufacturers’ instructions, the ambient air of the models in our range should not exceed 40°C as an increase in temperature means an increase in explosion hazard. This instruction is particularly important for appliances in commercial kitchens that are continuously in use and emitting steam. Each article description will tell you exactly whether or not the item is suitable for use in professional or industrial environments. Some basic models are not equipped to handle areas with heavy dust or acid stress as they can be found in assembly halls. Special units are also required if the ventilation system incorporates professional fume hoods to ensure that the motor is not damaged by the greasy air. In this case, we recommend the installation of the CasaFan GKB series
with IP54 splash water rating. The mounting, regular maintenance and checking of the filters is done by a specialist. We recommend changing the filters every six months or less if the air contains a lot of grease and pollutants.
At creoven, we are fan and ventilation experts. Please contact us if you have any questions about the best fan to meet your needs. We are happy to help!
Centrifgual Fan Accessories
Our shop offers everything you need to optimise and expand your centrifugal fans. Multi-stage speed controllers for regulating the fan speed offer convenient handling. We offer low-priced grilles made of robust steel wire to provide protection of the intake areas of the fan. To facilitate a choice of insulation options, a range of wall mounts and pedestals are also available.
Product pictures © Creoven.de