In our daily lives, ventilation is something we take for granted. However, in factories, hospitals, tunnels or large buildings, the correct circulation and renewal of air is vital to ensure a safe and healthy environment. Industrial fans play a key role in achieving this.
SODECA is internationally recognised for manufacturing industrial ventilation solutions, smoke extraction systems, staircase pressurisation, tunnel ventilation and indoor air quality improvement systems.
But how exactly do industrial fans work? What factors determine their performance? In this article, we will explain in simple terms the basic concepts of airflow, pressure and the operation of industrial fans.
Airflow is the amount of air a fan can move in a given period of time. Imagine having a fan at home: if you set it to maximum speed, you’ll feel it moving more air. That’s because the airflow has increased.
In industrial ventilation, airflow is measured in cubic metres per hour (m³/h), indicating how many cubic metres of air are displaced in one hour. The higher the airflow, the more air is moved, which is particularly important in spaces with a large number of people or where gases and fumes are generated, such as industrial kitchens or factories.
When a fan moves air, it does not always flow freely. Often, the air must pass through ducts, filters or face the resistance of the air itself in motion. This is where air pressure comes into play, which is divided into two types:
• Dynamic pressure: Generated by the movement of air and always positive.
• Static pressure: The force the air exerts on the walls of the ducts. This pressure is positive when it is higher than atmospheric pressure (overpressure) and negative when it is lower (underpressure).
The sum of both is the total pressure, which tells us how much force a fan needs to circulate air through a ventilation system.
To ensure a fan meets its purpose, tests are carried out in specialised laboratories. These tests measure:
- Airflow and pressure
• Testing how much air the fan can move under different conditions.
• Measuring the resistance faced by the equipment when moving air through ducts and filters. - Noise level
• Fans generate noise due to air friction and the rotation of their blades.
• Noise is measured in decibels (dB) to ensure it remains acceptable for its intended environment.
These tests follow international standards, such as ISO-3744 and ISO-3745 for noise measurements, and ANSI/AMCA 210-85 and its equivalent UNE 100-212-90, for airflow and pressure testing.
SODECA also offers its customers the possibility of carrying out FAT tests (Factory Acceptance Tests) to verify that the equipment meets all agreed specifications and requirements.
Performance is represented through characteristic curves, showing how airflow varies depending on the pressure in the system.
Imagine inflating a balloon: if the nozzle is open, air escapes freely (maximum airflow). But if you squeeze the nozzle, the air comes out with more pressure but in smaller quantities. The same happens with fans: as the system resistance increases (ducts, filters, etc.), the airflow decreases.
With these curves, engineers can select the right fan according to the needs of each installation.
There are three key factors that can alter a fan’s performance:
- Rotational speed: The faster the fan spins, the more air it moves, but this also increases energy consumption and noise.
- Blade size: A larger impeller moves a greater volume of air but requires a more powerful motor.
- Air density: In places with denser air (such as factories with high dust levels), the fan must exert more pressure to move the air
In more complex systems where multiple units are needed, fans can be arranged in two ways:
• In parallel: Multiple fans are placed side by side to increase total airflow.
• In series: Fans are placed one after another to increase pressure, useful in systems with very long ducts or many resistances.
These configurations are extremely useful in large ventilation projects, where airflow and pressure requirements can vary considerably. Equipping systems with units that can operate together or independently provides the necessary performance at any given time.
To help select the most suitable solution for your ventilation installation without the need for manual calculations, SODECA offers its customers the free QuickFan software — a tool that allows users to select products, obtain calculations and develop ventilation projects.
QuickFan has been developed by a team of technicians and sales professionals in close collaboration with SODECA’s clients, with the aim of delivering a practical and intuitive tool that offers solutions to the needs of technical departments and engineering firms.