A centrifugal fan creates the pressure difference that moves contaminated air through capture hoods, ductwork, separators and filters. In an industrial extraction system, its performance must be matched to the complete network; nominal airflow alone does not show whether the fan can overcome real operating resistance.
The fan’s role in extraction
Every component adds pressure loss. The fan must maintain the required airflow at the hood while filters load and different branches open or close. Its operating point is where the fan curve intersects the resistance curve of the actual installation.
Main centrifugal-fan configurations
Impeller geometry is selected for the duty and airstream. Clean- or lightly contaminated-air fans can prioritise efficiency. Fans that handle dust or conveyed particles need an impeller and casing suitable for the material load and potential abrasion. Low-, medium- and higher-pressure configurations serve different duct lengths, filters and transport requirements.
ALWO’s fan range includes solutions for general industrial extraction, air handling and pneumatic material transport, including ATDG and ATDC configurations for appropriate applications.
Selection criteria
- required airflow: calculated from all active capture points and realistic simultaneity;
- total pressure: includes hoods, ducting, bends, gates, separators, filters and discharge;
- airstream: clean air, fine dust, abrasive particles, hot air, mist or corrosive conditions;
- temperature and density: influence fan performance and materials;
- efficiency and control: motor, drive and variable speed are matched to the operating range;
- noise and vibration: installation, balancing, isolation and duct connections are considered;
- maintenance access: bearings, drives and wear areas must be inspectable.
Common selection errors
An undersized fan cannot maintain source capture. An oversized fan can increase energy use, noise, duct wear and replacement-air demand. Installing a larger motor does not correct unsuitable hood geometry or excessive network resistance. Selecting only for a clean filter may also allow airflow to collapse as pressure drop rises.
Variable-speed operation
Speed control can adapt airflow to active branches, but the control logic must preserve minimum transport velocities and any process safety requirements. Pressure sensors, gate status and filter condition can provide the demand signal.
Commissioning and maintenance
Commissioning confirms airflow, pressure, rotation, motor load, vibration and the operating point under representative conditions. Maintenance tracks bearings, balance, impeller wear, flexible connections and deposits. A trend in vibration or power can reveal a developing fault.
Browse ALWO centrifugal fans or contact our engineering team with airflow, pressure and airstream data.
