Frequently asked questions
In an axial fan, the airflow moves in the longitudinal (axial) direction of the drive shaft. In a radial or centrifugal fan, the air is drawn in axially, deflected 90°, and blown out transverse to the longitudinal (radial) direction of the shaft.
With an axial fan, air flows through the impeller parallel to the drive shaft. From this, therefore, this type derives its name. Since the required propulsion of the air is obtained by a number of somewhat screw blade-shaped blades that move perpendicular to the direction of flow of the air, one also speaks of a screw fan.
Axial fans, compared to centrifugal fans, can move a large amount of air with little electrical power. Since these fans cannot achieve high pressure, they are best used in low-pressure systems. Additional disadvantages are turbulence and a high noise level. Depending on the arrangement of the structure, there are different types of axial fans. Examples include wall and ring fans.
In the most common design, this type consists of an impeller, surrounded by a housing (air guiding ring) and for driving an electric motor (AC or EC). The housing often also serves as a wall mount. If the axial fan is integrated for mounting in a duct system, it is also called a tube fan. Usually they then have a flange on both sides to attach it to the pipes. Axial fans that do not have a housing are also referred to as table or ceiling fans.
With a centrifugal fan, air enters the impeller axially and is discharged radially into the housing.
When looking for a centrifugal fan, it is important to ask some essential questions. There are many available options, which may make the choice more difficult. We would like to help you with some criteria. Of course, the basics are the most important: in what kind of working environment will the fan be used? Working conditions and the environment play a big role. We list a number of points for you:
We list a number of points for you:
- How much air and pressure should the fan be able to handle?
- What is the available power supply on site?
- What type of drive do you desire?
- What type of medium is being transported?
- Are you dealing with higher temperatures?
- Will the centrifugal fan have an indoor or outdoor installation?
- What is the desired sound pressure level?
- What about explosion safety?
A centrifugal fan is suitable in a variety of applications. They are often ordered for (industrial) kitchens, offices, schools, workshops and the hospitality industry. A big advantage of the centrifugal fan is the noise level: this is a lot lower, which makes installing this fan perfectly suitable for offices or schools. Even in heavier industries such as extracting at a woodworking machine is no problem for the centrifugal fan.
Some examples of functions of a centrifugal fan:
- Exhausting fumes;
- Exhausting gases and dust;
- Flowing the room dry;
- Cooling and heating;
- Transporting bulk;
- Air exchange;
- Filtering
The difference is that with a single-inlet extraction motor the air is drawn in from one side and with a double-inlet extraction motor the air is drawn in from both sides.
Plug fans are designed for use where space saving is required. In any application for moving large volumes of clean or slightly dusty air at low pressure. This series of fans uses impellers with backward curved blades that have high efficiency.
A roof fan is placed in the roof and ensures that ventilation is good, preventing polluted air from sticking around. A roof fan falls under mechanical ventilation.
Roof fans are designed to provide your building or space with efficient and effective ventilation. Whether it is to remove smoke, improve air quality or reduce heat accumulation, roof fans are the perfect solution for your needs.
They are available in a variety of shapes and sizes.
Vapor hood exhaust fans should be suitable for the moisture present. Their motors have at least protection class IP 55 if placed in the air stream. The motors are equipped with thermal fuses that switch off the motor in case of overheating. It is recommended to use fans with motors outside the airflow. Temperature resistance of 40°C to 60°C for exhaust air from fume hoods of kitchens with low to medium-loading kitchen appliances has been found to be sufficient in practice. For high to very high load kitchen appliances, a motor outside the airflow and appropriate temperature-resistant fans are necessary. Increasing pressure losses during operation due to fouling of filters and ducts must be taken into account when calculating fan head. By using speed control, the speed and thus the operating point of the fan can be automatically adjusted according to a flow measurement. In practice, fans with metal blades are used because they are less likely to become unbalanced due to grease accumulation than plastic fans. When plastic fans are used, temperature resistance also becomes important. Centrifugal fans with forward-curved blades should be avoided because they have no self-cleaning effect and become unbalanced more quickly.
Front bent paddle wheel:
These paddle wheels have a large number of short blades. Due to this shape, the impeller has a very high efficiency. The forward curved paddle wheel builds compact, which means that the fan has very limited dimensions. The impeller is made of galvanized sheet steel.
Backward-curved impeller wheel:
These paddle wheels are characterized by a smaller number of blades that are proportionally larger. This paddle wheel is made of aluminum and can have a paddle efficiency of up to 82%. Also, the backward curved paddle is resistant to heavy pollution.(catering/industrial kitchens, ...)
