Which unit is commonly used to express vibration velocity in maintenance diagnostics?

• A. mm/s
• B. m/s
• C. g
• D. Hz

Answer: (A)

In vibration diagnostics, quantities are categorized as velocity, acceleration, or displacement. Vibration velocity is typically reported in millimeters per second (mm/s). This unit provides a practical, intuitive scale for the small-to-moderate vibration levels common in machinery and aligns with industry standards and measurement tools used in condition monitoring. Using meters per second would be less convenient for typical vibration magnitudes; g measures acceleration (not velocity); Hz measures how often the vibration repeats (frequency), not the speed of the vibration. So mm/s is the standard way to express vibration velocity.