Noise has always been present in control valves.It is a natural side effect of the turbulence and
energy absorption inherent in control valves. This chapter will address how noise is created, why it can be a problem, and methods to attenuate noise created in control valves.
The major problem with industrial noise is its affect on humans. Companies usually build town border stations on sites remote from residential developments. Isolation, however, is not always possible, and noise prevention is a must.
The U.S. Occupational Safety and Health Act (OSHA) establishes maximum permissible noise
levels for all industries whose business affects interstate commerce. These standards relate
allowable noise levels to the permissible exposure time. Notice in table 6-1 that the maximum
permissible levels depend upon the duration of exposure. For example, the maximum sound level a person should be exposed to for an eight hour day is 90 dBA. These maximum sound levels have become the accepted noise exposure standard for most regulatory agencies. Thus, they have become the standard by which much noise generating equipment has been specified and measured.