Industrial Fans, Blowers & Air Movement Equipment worked example

Inlet/Outlet Velocity at 99% effective open-area factor: a worked example

Push effective open-area factor up to 99% and the picture changes. This example computes every intermediate figure at that operating point. Use it when checking inlet velocity, outlet velocity, duct connection sizing, discharge speed, or dust collection transport assumptions.

The inputs for this scenario

  • Airflow through the opening: 12,000 CFM (unchanged)
  • Inlet or outlet free open area: 8 sq ft (unchanged)
  • Effective open-area factor: 99 % (raised for this scenario; the documented default is 92)

Working through the calculation

  • Applying the documented formula (Raw inlet or outlet velocity = airflow through opening รท inlet or outlet open area) to the inputs above produces each figure below.
  • At this operating point the engine returns 1,485 ft/min for effective inlet or outlet velocity, the number this scenario is built around.
  • At this operating point the engine returns 1,500 ft/min for raw inlet or outlet velocity.
  • At this operating point the engine returns 99 % for open-area efficiency allowance.
  • At this operating point the engine returns 8 hr for runtime.

How this compares with the baseline

  • Against the tool's baseline example, where effective open-area factor sits at 92% and the headline result is 1,380 ft/min, this scenario comes in 7.61% above the baseline at 1,485 ft/min.
  • It divides airflow by opening area for a raw face velocity, then multiplies by an effective open-area factor to account for screens, guards, and frame blockage. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Effective inlet or outlet velocity: 1,485 ft/min (headline result)
  • Raw inlet or outlet velocity: 1,500 ft/min
  • Open-area efficiency allowance: 99 %
  • Runtime: 8 hr

Run it with your numbers

  • Every input above is editable in the live Inlet/Outlet Velocity calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.