📳 Mechanical Vibration Measurement
Measurement and assessment of mechanical vibrations affecting humans — whole-body vibrations and hand-arm vibrations at workplaces according to ISO 2631 and ISO 5349.
Overview
Measurement of mechanical vibrations at workplaces is a mandatory work environment testing required by the Labor Code and the Regulation of the Minister of Labor of June 12, 2018. Mechanical vibrations are divided into whole-body vibrations (affecting the entire body through feet, buttocks or back) and local vibrations (transmitted through the upper limbs — hand-arm system).
Standard PN-EN ISO 8041 specifies requirements for measuring instruments (vibrometers) used to measure vibrations affecting humans, while exposure assessment is conducted according to PN-EN ISO 2631-1 (whole-body vibrations) and PN-EN ISO 5349-1 (local vibrations). The assessment parameter is the weighted vibration acceleration aw in m/s² expressed as root mean square (RMS) or vibration dose VDV.
Exceeding the NDN (maximum permissible intensity) values of vibrations in the work environment — 0.8 m/s² for whole-body vibrations and 2.8 m/s² for local vibrations (8-hour exposure value) — requires preventive measures. Measurements are performed by accredited OSH laboratories, and results are documented in the vibration exposure assessment card.
Method principle
Measurement consists of recording vibration acceleration using piezoelectric transducers (accelerometers) placed at the point of body contact with the vibrating surface. The signal from the accelerometer is processed by correction filters (frequency weighting Wk, Wd, Wh according to ISO 8041), which reflect human sensitivity to vibrations as a function of frequency. The result — weighted vibration acceleration aw — is expressed in m/s² RMS or as vibration dose VDV in m/s^1.75.
Applications
- Exposure assessment for vehicle and construction machine operators (whole-body vibrations)
- Local vibration measurements when operating hand tools (drills, grinders, saws)
- Workplace studies for occupational risk assessment purposes
- Vibration monitoring in construction (impact on buildings and residents)
- Diagnostic tests for vibration syndrome (hand-arm vibration syndrome — HAVS)
- Control of vibration platforms in physiotherapy
Key parameters
| Parameter | Value |
|---|---|
| NDN whole-body vibrations (8h) | 0.8 m/s² (action, A(8)) / 1.15 m/s² (NDN) |
| NDN local vibrations (8h) | 2.8 m/s² (action) / 5.0 m/s² (NDN) |
| Frequency range | 1–80 Hz (whole-body), 8–1000 Hz (local) |
| Weighting filters | Wk, Wd (whole-body — ISO 2631), Wh (local — ISO 5349) |
| Measurement time | Min. 3 measurements of ≥ 1 min each (repetitive activities) |
| Measurement uncertainty | Typically 10–15% (k = 2) |
Standard
- Standard number
- PN-EN ISO 8041-1:2017-07
- Title (PL)
- Odpowiedź człowieka na drgania — Przyrządy pomiarowe — Część 1: Przyrządy do pomiaru drgań ogólnych
- Title (EN)
- Human response to vibration — Measuring instrumentation — Part 1: General purpose vibration meters
Step-by-step procedure
1. Workplace identification
Describe workplace, vibration source, worker exposure time. Select vibration type (whole-body/local).
2. Meter calibration
Connect vibration calibrator to accelerometer. Check reading 10 m/s² at 159.2 Hz. Deviation max ±3%.
3. Sensor mounting
Whole-body: place seat pad under operator's buttocks. Local: attach accelerometer to tool handle (mechanical adapter).
4. Measurement parameter setting
Select weighting filter (Wk/Wd for whole-body, Wh for local). Set averaging time and measurement range.
5. Measurement
Record vibrations during typical operator work. Perform min. 3 measurements of ≥ 1 min each. Record daily exposure time duration.
6. Calibration verification
After measurements, check meter calibration again with calibrator. Deviation > 3% disqualifies measurement.
7. Daily exposure calculation
Calculate A(8) — daily exposure normalized to 8 h: A(8) = aw × √(T/T0), where T — exposure time, T0 = 8h.
8. Comparison with NDN
Compare A(8) with threshold values and NDN according to Ministry Regulation. Assess occupational risk.
9. Report
Prepare measurement report containing results, conditions, workplace identification and preventive recommendations.
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Vibration meter (vibrometer) | SVANTEK SV 106A (6-channel), Brüel & Kjær 4447, Larson Davis HVM200 | 25 000–80 000 PLN |
| 3-axis seat accelerometer | SVANTEK SV 38V, Brüel & Kjær 4515-B-002 (seat pad) | 3 000–8 000 PLN |
| Hand-arm accelerometer | SVANTEK SV 105A, Brüel & Kjær 4524-B-002 (handle adapter) | 2 000–6 000 PLN |
| Vibration calibrator | Brüel & Kjær 4294, SVANTEK SV 110 | 5 000–15 000 PLN |
| Analysis software | SVANTEK Supervisor, Brüel & Kjær BZ-5503 | 3 000–10 000 PLN |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Reference calibrator | — | Vibration standard 10 m/s² at 159.2 Hz, with current calibration certificate |
| Seat pad | — | Foam disc with pockets for 3-axis accelerometer, standardized according to ISO 10326-1 |
| Mounting adapters | — | Straps, adhesives, magnetic holders for mounting accelerometers on tools and machines |
Health and safety (OHS)
- Perform measurements under normal operating conditions — do not modify work process
- Use hearing protection when simultaneous noise > 85 dB(A)
- Meter operator should not interfere with the work of the tested worker
- Avoid measurements at extreme temperatures (effect on piezoelectric accelerometers)