Noise first action level

The first action level is a daily personal noise exposure of 85 dB, expressed as 85dB(A). 

At the first action level an employee must be provided with ear protection (ear muffs or ear plugs) on request. At the second action level the employer must reduce, so far as is reasonably practicable, other than by providing ear protection, the exposure to noise of that employee. 

New regulations introduced in 2006 reduce the first action level to 80dB(A) and the second level to 85dB(A) with a peak action level of 98dB(A) or 140 Pa of pressure. Every employer must make a noise assessment and provide workers with information about the risks to hearing if the noise level approaches the first action level. They must do all that is reasonably practicable to control the noise exposure of their employees and clearly mark ear protection zones. Employees must wear personal ear protection while in such a zone. 

The exposure criterion used in these Regulations is the equivalent noise level over the working day or shift (Lep ci). Three actions levels are identified, the first action level is an lEP,d of 85 dB(A) when an employee has to be provided with hearing protection on request (Reg. 8(1)), the second action level is an exposure of 90dB(A) or more when hearing protection must be provided and worn (Reg. 8(2)) and the third level is the peak action level when a peak sound pressure level of 200 pascals occurs when hearing protection must, again, be provided and worn. 

Regulation 12 modifies section 6 of HSW to impose a duty on manufacturers and suppliers to inform customers when the noise level emitted by their product exceeds the first action level, i.e. 85dB(A) Lep. ... 

Regulation 4 requires that every employer shall, when any of his employees is likely to be exposed to the first action level or above, or to the peak action level or above, ensure that a competent person makes a noise assessment which is adequate for the purposes ... 

First action level - daily personal noise exposure (LEP,d) of 85dB(A)... 

Where the daily noise exposure exceeds the first action level, employers must ... 

A baseline audiogram shall be established on employees exposed at or above the action level within 6 months of the first exposure. Employees shall be notified of the requirement that testing shall be preceded by at least 14 hours without exposure to workplace noise. Hearing protectors may be worn as a substitute to this requirement. 

A liquid level control loop, shown in Figure 7.5, is essentially a single dominant capacitance without dead time. Typical hold-up times are from 5 to 15 min. Typically, processes that are dominated by a single, large capacitance are the easiest to control. However, liquid level processes are not necessarily as simple as they first appear to be. In many liquid level control situations, considerable noise in the measurement is present as a result of surface turbulence, stirring, boiling liquids, etc. The fact that this noise exists often precludes the use of derivative action in the controller. Still, some applications use unique methods of level measurement to minimize the noise in the measurement in order to apply derivative action in the controller. 

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