允许振动速度（ISO 10816）

Vibration velocity is the speed at which a vibrating surface moves back and forth, measured in mm/s RMS (root mean square). It is the most widely used parameter for evaluating machine condition because it correlates well with vibration energy and the risk of mechanical damage.

ISO 10816 and ISO 20816 define permissible velocity limits organized by machine class and evaluation zone.

ISO 20816 is the modern replacement for ISO 10816. The zone boundaries and machine classes are essentially the same for housing (non-rotating parts) vibration evaluation.

ISO 20816 adds shaft vibration requirements and updated measurement practices. For broadband velocity RMS evaluation on machine housings — the most common industrial use — the classic ISO 10816 limits still apply.

Vibration velocity is measured with an accelerometer or velocity sensor mounted on the machine bearing housing. The sensor signal is processed by a vibration analyzer to produce a broadband RMS velocity value in mm/s.

Measurements should be taken in three directions: horizontal, vertical, and axial. The highest reading is used for zone evaluation. The standard frequency range is typically 10–1000 Hz.

Zone C: Vibration is tolerable only for limited periods — plan corrective action soon.

Zone D: Vibration is severe enough to cause damage — stop the machine immediately if possible and investigate the root cause.

Common corrective actions include: dynamic re-balancing, shaft alignment correction, bearing replacement, looseness repair, or addressing structural resonance.

For most industrial machines, a piezoelectric accelerometer with integrated electronics (IEPE/ICP type) is the standard choice — the acceleration signal is electronically integrated to velocity.

For low-frequency applications below 10 Hz, electrodynamic velocity sensors may be preferred. Ensure the sensor frequency range covers at least 10–1000 Hz per ISO 10816.