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Noise Control Practices in the Workplace

Noise Control Practices in the Workplace . STEP Network Meeting August 17, 2005. Noise. Before We Discuss Noise Control Let’s Review Some Noise Concepts. Noise Measurements. Noise Levels are Expressed as Decibels (dB). 1+1+1 Does Not Equal to 3.

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Noise Control Practices in the Workplace

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  1. Noise Control Practices in the Workplace STEP Network Meeting August 17, 2005

  2. Noise Before We Discuss Noise Control Let’s Review Some Noise Concepts

  3. Noise Measurements Noise Levels are Expressed as Decibels (dB)

  4. 1+1+1 Does Not Equal to 3 The Decibel is a Logarithmic Unit of Measure So We Can’t Simply Add Numbers

  5. Keep the Calculator in the Desk We Can Use a Few Rules of Thumb

  6. “Shake, Rattle, and Roll” How We Perceive Noise

  7. High Frequency Noise • Power Tools, Saws, Grinders • Other High RPM Equipment • Sudden Release of Pressure

  8. High Frequency Noise High Frequency Noises Deflect Easier, Are Easier to Shield, Are Easier to Insulate

  9. Low Frequency Noise • Power Presses • Pumps, Compressors • Other Low RPM Equipment

  10. Low Frequency Noise Low frequency Noises Can Travel Around and Through Objects and Are Harder to Shield and Absorb

  11. Harmful Effects Harmful Effects of Noise Are Related to the Noise Dose

  12. Is the Noise Harmful? Ask Yourself: How Loud, How Long, How Many Times?

  13. Noise Dose is a Combination • Intensity of Noise (how loud) • Duration of Noise Exposure (how long) • Frequency (how many times during the day are they exposed to such a noise)

  14. Noise • Regulated as an 8 hour Time Weighted Average (TWA) • An 8 hr TWA of 90 dBA is designated as a Noise Dose of 100%

  15. First Rule of Thumb 5 dB Halving Rule

  16. 5 Decibel Halving Rule For Each 5 dB Increase in Noise, In order to be Equivalent to the Previous Dose You Must Half the Allowable Exposure Time

  17. Equivalent Dose of 90 dBA Over an 8 Hour TWA Period • 95 dBA over 4 Hour TWA Period • 100 dBA over 2 Hour TWA Period • 105 dBA over 1 Hour TWA Period • 110 dBA over ½ Hour TWA Period

  18. Duration (How Long) The 5 dB Rule Can Be Useful in Estimating Whether a Noise or an Activity Would Result in Employees Being Exposed to Noise In Excess of the PEL

  19. Example • An Employee Must Enter a Pump Room and Conduct Preventative Maintenance • The Small Portable Sound Level Meter Reads 105 dBA Inside the Pump Room • How Long Could the Employee Stay in the Pump Room Without Exceeding the Dose Equivalent Noise Exposure of 90 dBA over an 8 hour TWA?

  20. Answer Employee Noise Exposure for 1 Hour at 105 dBA Would Be the Dose Equivalent Exposure of 90 dBA for an 8 Hr TWA .

  21. Administrative Controls Likewise, Limiting Employee Exposure Time to Noise Can Help Reduce the Possibility of Hearing Loss

  22. Watch Where You’re Standing Employee Noise Exposures Often Depend on How Close They Are to the Noise Source

  23. Distance Noise Quickly Decreases as You Move Away from the Noise Source

  24. 6 dB Double Distance Rule Noise Will Decrease 6 dB Each Time You Double the Distance (free field, point source only)

  25. 6 dB Rule Would Not Apply

  26. 6 dB Rule Would Not Apply

  27. Distance From the Noise Source Is It Possible to Move the Employee Workstation or the Noise Source?

  28. If a Tree Falls in the Woods… Moving the Employee or the Noise Source Doesn’t Eliminate the Loud Noise, it Just Reduces the Employee Exposure to it!

  29. Think Out Loud In Moving the Source, Have You Created a Problem for Someone Else?

  30. Isolation Methods Can You Isolate the Noise Source or The Employee From the Noise Source?

  31. Enclosing the Employee The Cab of Heavy Earth Moving Equipment is a Good Example. They are Insulated (and Air Conditioned).

  32. Isolation Methods • Install Barriers Between the Employee and Noise Source • Enclose the Noise Source • Enclose the Employee

  33. Think Out Loud Be Careful When Constructing Barriers or Enclosures. Noise May be Deflected Backwards Off the Barriers or the Walls of the Enclosure Which Can Increase the Noise Intensity on the Noise Source Side. Employees who Must Service Equipment or Conduct Work in Those Areas May Now be Exposed to Greater Noise than Before

  34. Deflection of Sound Waves in Enclosure Creates Louder Noise

  35. Noise Absorbing Material The Good, The Bad, and The Ugly

  36. The Good • Noise is Absorbed, It’s Gone, It Wouldn’t Bother Anyone Anymore • High Frequency Noises are Easier to Absorb

  37. The Bad • Some Types Can be Fragile • Some Types Can be Hard to Clean • Some Can Be Expensive

  38. The Ugly • Some Types Can Be Very Expensive • Some Types Won’t Hold Up to Chemicals or Moisture • Some Types Can be Combustible

  39. Transmitting Vibration Noise and Vibration Can Be Transmitted to Other Surfaces Which Then also Transmits Noise

  40. Controlling Noise Generated by Vibration Sources • Dampners, Springs, or Isolation Material under Motors and Large Equipment • Ensure Plates, Covers, Doors, and Access Panels are Securely Attached • Bent or Warped Shafts on Motors and Fans Can Create Vibration • Bad Bearings, Flywheels, Pulleys, Fan Blades, and Belts

  41. By the Way Poor Maintenance Can Be a Major Source of Noise Exposure and One Which is Often Consider Economically Feasible.

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