BY VEDANT PATHAKHow to select an industrial fan: why the duty point matters
Short answer: A fan isn't selected by airflow alone. Where the fan curve meets the system curve decides efficiency, power and life.
Every fan has a performance curve: pressure against airflow. Every duct system has a resistance curve that rises with the square of flow. Where they cross is the duty point, and that's where your fan will actually run, whatever the datasheet says.
Common mistakes
- Adding big safety margins. An oversized fan runs throttled, wasting power and causing vibration
- Ignoring density. Hot gas is lighter, so pressure and power change with temperature and altitude
- Selecting off the peak. Running left of the peak pressure point causes surging
What I check in fan design software
- Duty point near the best-efficiency point
- Margin on flow and pressure (typically 10–20%, not 50%)
- Motor power at the worst case (cold start)
- Tip speed, noise and material for the gas
Try the fan curve simulator on my homepage. Push the system resistance up and watch the duty point slide.
A well-selected fan can cut 15–30% of a dust collection system's power bill. That's often the fastest payback in the plant.