Industrial Fans, Blowers & Air Movement Equipment worked example

Vibration Margin with allowable fan vibration velocity of 0.45 in/s: a worked example

What does the result look like when allowable fan vibration velocity reaches 0.45 in/s? The full calculation is worked below with real intermediate numbers. Use it when deciding whether a fan or blower passes vibration test, needs balancing, or requires mechanical review.

The inputs for this scenario

  • Allowable fan vibration velocity: 0.45 in/s (raised for this scenario; the documented default is 0.18)
  • Measured fan vibration velocity: 0.11 in/s (unchanged)
  • Reference vibration limit: 0.18 in/s (unchanged)

Working through the calculation

  • Applying the documented formula (Vibration margin = allowable vibration level - measured vibration level) to the inputs above produces each figure below.
  • At this operating point the engine returns 189 % for vibration margin percent, the number this scenario is built around.
  • At this operating point the engine returns 0.34 in/s for vibration margin.
  • At this operating point the engine returns 0.45 value for allowable vibration level.
  • At this operating point the engine returns 0.11 value for measured vibration level.

How this compares with the baseline

  • Against the tool's baseline example, where allowable fan vibration velocity sits at 0.18 in/s and the headline result is 38.89 %, this scenario comes in 386% above the baseline at 189 %.
  • A figure at this level is achievable when allowable fan vibration velocity is genuinely sustained, not just peaked for a shift. A single overall velocity number hides the diagnosis — two fans can share the same margin while one has imbalance and the other a failing bearing, so confirm with spectral analysis.

Results at a glance

  • Vibration margin percent: 189 % (headline result)
  • Vibration margin: 0.34 in/s
  • Allowable vibration level: 0.45 value
  • Measured vibration level: 0.11 value

Run it with your numbers

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

Last reviewed 2026-05-12.