A Primer For Assessing, Interpreting And Controlling Occupational Vibration Exposure

Transcription

1 A Primer For Assessing, Interpreting And Controlling Occupational Vibration Exposure 10th Applied Ergonomics Conference March 13, 2007 Tom Albin, PE, CPE Auburn Engineers, Inc ENGINEERS

2 Objectives Why vibration exposure is of concern Introduce basic terminology Introduce standards and guidelines US and International Hand/Arm and Whole Body Introduce analysis techniques Direct assessment of vibration exposure Indirect assessment of vibration exposure ENGINEERS

3 Why is Vibration Exposure of Concern? Performance effects, e.g. difficulty in reading displays, eye-hand coordination, motion sickness, etc. Health effects, e.g. Hand/Arm Vibration Syndrome, Carpal Tunnel, etc ENGINEERS

4 Vibration Terminology ENGINEERS

5 Vibration Terminology - Vibration Direction (Orthogonal Axes) ENGINEERS

6 Vibration Terminology - Amplitude A description of the maximum excursion of the vibration from the neutral point Amplitude Typically given in meters/second 2, or In g (gravity, or 9.81 m/second 2) ENGINEERS

7 Vibration Terminology - Frequency The number of oscillations per Time Period T (seconds) T ENGINEERS

8 Vibration Standards and Guidelines ENGINEERS

9 Vibration Performance Standards/Guidelines Not covered in this presentation Refer to publications such as Mil Std ENGINEERS

10 Vibration Standards Health and Safety Effects Hand Arm ISO 5349 EU Vibration Directive ACGIH Whole Body ISO 2631 EU Vibration Directive ACGIH ENGINEERS

11 Direct Vibration Measurement Measure Amplitude at various frequencies Some frequencies given more weight according to specification in ISO 5349 or 2631 Weighted values used to make risk assessment Most current equipment will do this automatically ENGINEERS

12 Direct Measurement of Vibration Requires measurement equipment ENGINEERS

13 Hand Arm Vibration ACGIH Exp. Time (hrs) <m/s 2 4 < < < 2 8 < 1 12 EU Action Limit ( Shouldn t Exceed) 2.5 m/s2 Exposure Limit (Can t Exceed) A(8) 5 m/s2 A(8) ENGINEERS

14 Whole Body ACGIH Requires direct measurement and weighting EU Action Limit ( Shouldn t Exceed) 0.5 m/s2 A(8) Exposure Limit C (Can t Exceed) 1.15 m/s2 A(8) ENGINEERS

15 Indirect Vibration Measurement What to do if you don t have ready access to vibration measurement equipment Two sources of indirect vibration signature data Manufacturer Check that it s weighted in accordance with ISO 5349 or 2361 National Institute for Working Life (NIWL) database Already weighted in accordance with ISO 5349 or ENGINEERS

16 NIWL Vibration Database ENGINEERS

17 NIWL Database Can be used to estimate the vibration signature for the situation of interest (or similar) Also provides calculators to assess risk Example 1. Hand Arm Example 2. Whole Body ENGINEERS

18 Assessing Vibration Exposure ENGINEERS

19 ACGIH Hand An angle grinder is used each day for 2 hrs. The manufacturer states that it has a vibration signature of 5 m/s 2. This is acceptable as the amplitude is less than the limit for the exposure time ACGIH Exp. Time (hrs) < m/s 2 4 < < < 2 8 < ENGINEERS

20 NIWL Hand An employee uses an angle grinder for 2 hours per day; according to the database, it has a vibration signature of 5 m/s ENGINEERS

21 NIWL Calculator EU assessment indicates can be used up to 2 hrs/day without exceeding the AL or up to 8 hrs without exceeding the EL ENGINEERS

22 NIWL Hand An employee(s) uses two tools each day An angle grinder, 5 m/s 2 for 2 hrs, and A chipping hammer, 2.5 m/s 2 for 1 hr ENGINEERS

23 NIWL Calculator EU assessment indicates Caution as the exposure exceeds the AL Can be used up to 8 hrs without exceeding the EL ENGINEERS

24 NIWL Calculator Playing What if? with the calculator What is the maximum vibration signature allowable for the angle grinder if both tools are to be used? Alternatively, for how long of a time could it be used? ENGINEERS

25 NIWL Calculator ENGINEERS