Industrial Fans, Blowers & Air Movement Equipment worked example

Motor Sizing with design airflow of 30,000 CFM: a worked example in industrial fans, blowers & air movement equipment

This scenario runs the motor sizing calculation on the strong side: design airflow of 30,000 CFM, with every other input held at its documented default. Use it when selecting a motor size for centrifugal fans, axial fans, blowers, or exhaust systems before checking final brake horsepower.

The inputs for this scenario

  • Design airflow: 30,000 CFM (raised for this scenario; the documented default is 12,000)
  • Design static pressure: 6 in. w.c. (unchanged)
  • Power conversion basis: 0 hp / CFM-in. w.c. (unchanged)
  • Motor service factor or sizing margin: 1.15 x (unchanged)

Working through the calculation

  • Applying the documented formula (Estimated motor size = design airflow × design static pressure × power conversion basis × motor service factor or sizing margin) to the inputs above produces each figure below.
  • At this operating point the engine returns 45.54 hp for result, the number this scenario is built around.
  • At this operating point the engine returns 39.6 value for base product.
  • At this operating point the engine returns 1.15 x for multiplier.
  • At this operating point the engine returns 180,000 value for factor a x b.

How this compares with the baseline

  • Against the tool's baseline example, where design airflow sits at 12,000 CFM and the headline result is 18.22 hp, this scenario comes in 150% above the baseline at 45.54 hp.
  • Use it for early scoping or to validate a quoted motor size before you have a full fan curve and brake horsepower data in hand. Treat this as a target state: the delta against the baseline quantifies what the improvement is worth before you commit to chasing it.

Results at a glance

  • Result: 45.54 hp (headline result)
  • Base product: 39.6 value
  • Multiplier: 1.15 x
  • Factor A x B: 180,000 value

Run it with your numbers

  • Every input above is editable in the live Motor Sizing calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.