1 / 53

Noise and Vibration

Noise and Vibration. Chapter 21. Noise - History. 100 Years – Noise Exposure results in permanent hearing Loss! 1918 – Vibration causes permanent damage to hands and fingers. Sound Wave. Physics of Sound. C = Speed of propagation λ = c/f C = speed f = frequency λ = wavelength.

stanleyw
Download Presentation

Noise and Vibration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Noise and Vibration Chapter 21 Industrial Hygiene

  2. Noise - History • 100 Years – Noise Exposure results in permanent hearing Loss! • 1918 – Vibration causes permanent damage to hands and fingers. Industrial Hygiene

  3. Sound Wave Industrial Hygiene

  4. Physics of Sound • C = Speed of propagation • λ = c/f • C = speed • f = frequency • λ = wavelength Industrial Hygiene

  5. Physics • Frequency = 1000 cycles per second • C = 1128.6 feet/sec (344 meters/sec) • Λ = 1128.6/125 hz • =9.02 feet Industrial Hygiene

  6. Physics • Sound is pressure • 1 P = 1 Newton/m2 • P = Pascal • L = 10Log(P/Pref)2 • Pref = 20 µPa Industrial Hygiene

  7. Physics • Sound Pressure = 0.2 Pascals What is • Sound level? • L = 10Log(0.2/20 µPa)2 • L = 80 dB • dB = decibels (deci = 1/10) Industrial Hygiene

  8. Directional Industrial Hygiene

  9. Sound • dBA vrs dBC weighting • A = close to human hearing • C = Flat Industrial Hygiene

  10. Industrial Hygiene

  11. Noise Control • Barriers • Distance • Isolation Industrial Hygiene

  12. Limits • 84 dBA 8 hours AF/DOD (4 dB) • 90 dBA 8 hours OSHA (5dB) • 85 dBA 8 hours TLV (3dB exhange) See Chapter 21, page 445 See TLV booklet page 117. Industrial Hygiene

  13. Limits 5 dBA exchange Rate • 90 dBA for 8 hours • 95 dBA for 4 hours • 100 dBA for 2 hours What is the limit for 30 minutes? Industrial Hygiene

  14. Distance • If a noise source is 96 dBA at 10 feet • What is the intensity at 20 feet? Industrial Hygiene

  15. Distance • Answer: 90 dBA • Calc: L =L- 20 Log(D2/D1) L = L -20 Log (20/10) L = L- 20 Log (2) L = L-20 (0.301) L = 96dbA - 6.01 dB = 90dBA Rule of Thumb: Double distance, drop 6 dB Industrial Hygiene

  16. Noise Calc - Activity • A noise source is 102 dBA (Measured) at • 25 feet. What will the noise level be at 60 feet? Industrial Hygiene

  17. Activity • L = 20 Log(D2/D1) • L = 20 Log (60/25) • L =20 Log(2.4) • L = 20 (0.38) • 7.6 dB • 102 dBA – 7.6 dBA = 94.4 dBA Industrial Hygiene

  18. Controls • Turn the Noise Source • Place Barriers (Frequency dependant) • Isolation/Absorption materials Industrial Hygiene

  19. Industrial Hygiene

  20. Industrial Hygiene

  21. Industrial Hygiene

  22. Industrial Hygiene

  23. General Notes • Lower Frequencies more difficult • Specialized materials Industrial Hygiene

  24. Hearing Exposure Effects: • Tinnitus – Ringing, buzzing, whistle • Indicator of damaging noise exposure • Acoustic Trauma – loss due to a sudden intense noise (Explosion) • Threshold Shift – change in the response of hearing in certain frequencies Industrial Hygiene

  25. Noise Induced Hearing Loss Industrial Hygiene

  26. Hearing Loss, Sources Industrial Hygiene

  27. Hearing Loss – Noise Induced Hearing Loss (NIHL Industrial Hygiene

  28. Rules of Thumb • Shout at 3 Feet • Loud Voice at 1 foot • It’s Hazardous Noise! Industrial Hygiene

  29. Speech Interference Level • SpIL = Limit to 55 dBA background • Difficulty using phones, communicating Industrial Hygiene

  30. Noise Measurement • Hand-held • Octave Band Analysis • Graphic Level Instruments Industrial Hygiene

  31. Moving the Source • rotation Industrial Hygiene

  32. Medical Examinations • Baseline • Periodic • Annual • 48 hours noise free • Threshold shifts Industrial Hygiene

  33. Medical Examinations • Threshold shift determination is • Frequency Dependant • Age factors • smoking Industrial Hygiene

  34. Noise Control • Hearing Protection 27 dBA 19-23 dbA 18-23 dBA Industrial Hygiene

  35. Noise Control 27 –33 dBA reduction Industrial Hygiene

  36. Noise Control Industrial Hygiene

  37. Noise Control • Noise Source: 117 dBA, 2 hours • V51Rs • Noise Exposure:? Industrial Hygiene

  38. Noise Exposure • 117-27 dbA = 90 dBA • Adequate? • In some cases, have to use plugs and muffs! Industrial Hygiene

  39. Vibration • Human exposure divided into: • Whole Body • Hand-arm vibration Industrial Hygiene

  40. Vibration • Causes: • Vibration induced White Finger (VWF) or • Raynauld’s syndrone Industrial Hygiene

  41. Vibration • Exposure: (Book) • 8 Million workers Industrial Hygiene

  42. Vibration - Charts Industrial Hygiene

  43. Vibration Duration m/s2 gDelta 4 Hrs < 8 hrs 4 0.40 g 2 hrs < 4 hrs 6 0.61 1 hr < 2 hrs 8 0.81 < 1 hr 12 1.22 G = 9.81 m/sec > 16 hz may need special consideration! Industrial Hygiene

  44. Variations: • UK 2.8 m/sec 8 hours • Canada Same. Industrial Hygiene

  45. Average Vibration • Average Vibration: 9.0 m/sec2 -Jackhammer (Time Limit?) Industrial Hygiene

  46. Average Vibration • After Training/Techniques: • 5.5 m/sec2 Industrial Hygiene

  47. ELV = Exposure Limit Value EAV = Exposure Action Value Industrial Hygiene

  48. Hand Direction Industrial Hygiene

  49. Stage Assessment Table Industrial Hygiene

  50. Industrial Hygiene

More Related