What Is a Vibration Meter? Types and Selection Criteria
A vibration meter is a portable instrument that measures the vibration of rotating machines such as motors, pumps and fans as velocity, acceleration or displacement.
A vibration meter is a portable instrument that measures vibration on the housing of rotating machines such as motors, pumps, fans, compressors and gearboxes. The probe is touched to the machine or held by a magnetic base, and the instrument shows vibration as velocity, acceleration or displacement. In periodic maintenance, comparing readings helps catch imbalance, looseness, misalignment and bearing wear early.
Measured quantities
| Quantity | UNI-T | Used for |
|---|---|---|
| Velocity (RMS) | mm/s or cm/s | General machine condition; imbalance and misalignment |
| Acceleration | m/s² | High-frequency vibration; early sign of bearing and gear damage |
| Displacement | µm or mm | Low-speed machines, large oscillations |
Selection criteria
- Measured quantity: For general maintenance, an instrument that measures velocity (RMS) is enough. If bearings are to be tracked, choose a model that measures acceleration; check in the datasheet which quantities it measures.
- Range and frequency response: The product data gives the UT315A a velocity range of 0–19.99 cm/s, a frequency response of 10 Hz–1 kHz and an accuracy of ±(5 % + 0.02 cm/s). Compare the values of the other models on the product pages.
- Probe and attachment: Models with a magnetic base or external probe make it easier to repeat a reading at the same point; to compare values, always measure at the same point and direction.
- Assessment: Acceptable vibration levels by machine class are given in the ISO 20816 series (formerly ISO 10816). The best comparison is with the same machine's own past readings.
- Power and use: The UT311A and UT312A product data lists 5 V DC charging, backlight, data hold and auto power-off after 5 minutes.
Common mistakes
- Measuring at a different point each time: The value changes with point and direction, so the trend cannot be followed.
- Touching loosely on painted or rusty surfaces: Without proper contact the reading is low and unstable.
- Deciding from a single reading: Note the value with the machine's load and speed and compare over time.
Vibration meters at Welibaba
The Vibration Meters category has 4 active products from Unit, all listed with prices: UT311A, UT312, UT312A and UT315A. For sound, light and air measuring instruments, see the environmental measuring instruments guide.
Frequently asked questions
What does a vibration meter measure?
The vibration of the machine housing; depending on the model as velocity, acceleration or displacement. The value most used in maintenance is the RMS vibration velocity.
Does a vibration meter show bearing failure?
Rising vibration can point to a bearing problem; the early trace of bearing damage usually shows in high-frequency acceleration. For a firm diagnosis, compare readings over time or have a vibration analysis done.
Where is the measurement taken?
At a solid, unpainted point close to the bearing housings, separately in the horizontal, vertical and axial directions. Use the same points at every inspection.