On 23-24 January 2007, EPA held an informal two day meeting in Washington to discuss revisions to the current hearing protector labeling regulation (40 CFR Part 211, Subpart B). As you may know hearing protectors are rated with a NRR number which is often in the range of 20-30, giving many the impression that the hearing protector is providing 20-30 dB of noise reduction. Long term usage of hearing protection is probably only good for 10-12 dB of noise reduction.

Observers expect EPA to issue a new rule before the end of the calendar year.

The National Academy of Engineering’s Magazine “Bridge” has published an article on “Engineering Controls” by Bob Bruce. You can see it at [nae.edu].

Noise can be the result of structure-borne vibrations from sources some distance from the receiver. CSTI Acoustics models the structure-borne noise using a statistical energy analysis technique.

Low-frequency vibration can interfere with workers’ ability to perform tasks. CSTI models the vibration from machinery and calculates the expected vibration on decks and bulkheads due to the vibration. The vibration is predicted in terms of the acceleration in m/s². These values can be compared with vibration criteria such as the NORSOK vibration standards. If the acceleration is in excess of the allowable levels, then treatments are developed to solve the problem.

CSTI Acoustics offers analysis of Acoustic Induced Vibration (AIV) for flare systems. AIV can occur downstream of pressure relief valves under certain pressure and flow conditions. The generated sound power is so intense that the piping can vibrate in a circumferential mode. Small connections subjected to the intense sound and vibration can fail. CSTI analyzes the situations and develops solutions to the problem.

On 23 January 2007, EPA will start an informal two day meeting in Washington to discuss revisions to the current hearing protector labeling regulation (40 CFR Part 211, Subpart B). As you may know hearing protectors are rated with a NRR number which is often in the range of 20-30, giving many the impression that the hearing protector is providing 20-30 dB of noise reduction. Long term usage of hearing protection is probably only good for 10-12 dB of noise reduction.