Noise at the workplace

What is to be considered regarding noise in workplaces?

Every employer has to keep his employees from potential harm which they are opposed to during their work. One of these aspects to protect them is to keep the work environment as quiet as possible. The noise emissions have to be reduced to a minimum. Especially in the industry sector, workers are often exposed to many machines which are combined even louder than a single one. There are certain guidelines, that every employer has to observe. On this page, we give you an overview on the most important facts. 

Legal basics:

Owners / employers are obliged to protect their employees against all hazardous dangers, which their daily work accompanies, and to commit to a healthy work environment.

Concerning noise protection, the workplace limit values must be observed according to DIN EN ISO 11690 part 1. As a general rule:

  1. Industrial workplaces: <80dB(A)
    •  85dB(A) must by no means exeeded, above that level employees have to wear ear protection!
  2. Office work: <55db(A)
  3. Work which takes a lot of focus: <45dB(A)

Indicators to danger evalutaion and measurement are in the „guideline for protecting employees against dangers caused by noise and vibration“ (LärmVibrationsArbSchV, www.dguv.de) and the „Guideline for occupational health prevention“ (ArbMedVV, www.bmas.de), each in the currently valid edition.

The noise exposure has to be measured always close to the worker’s ears (e.g. with a noise dosimeter).

Machine manufacturers must measure the sound pressure level of their systems in a measurement process (e.g. EN ISO 3746) according to the machine guideline (MRL) and indicate in their documents.

Only if the measured value is >85dB(A), the manufacturer has to indicate the sound pressure level (Lpa) and the sound power level (Lwa).

The sound pressure level is measured normally at 1m to the system from each side and the average calculated based on that.

2006/42/EG from June 9, 2006, no. 1.7.4.2.u, valid from Januar 1st, 2010:

Workplace-related emissions level Spl

Required data

98/37/EG from June  22, 1998

2006/42/EG from June 9, 2006 (valid from 1.1.2010)

< 70 dB(A)

< 70 dB(A)

Lpa < 70 dB(A)

or

Lpa = … dB(A)

71 – 85 dB(A)

71 – 80 dB(A)

Lpa = … dB(A)

> 85 dB(A)

> 80 dB(A)

Lpa = … dB(A)

and

Lwa = … dB(A) 1)

Table 1: Sound emission values according to EG machine guideline. Extraneous noises and the room itself (reflexing parts) are not calculated in the workplace-related emission level SPL. However, it contains susceptible supplements for measuring accuracy.

1) Lwa: Sound power level

 

If a machine is not part of exactly one workplace (e.g. a filter and extraction system), the measuring of noise emissions will be those of the system itself. The data does not evaluate the noise emissions within the room.

Noise basics:

Sound power level

„The sound power level Lw indicates in a logarithmic measure the whole sound power W of an emitted sound source.

Lw=10logW/W0  [dB]  

W0 is defined by 10-12 W (or 1 pW, reference sound power). In case the whole sound power in spread on a surface of 1m2 (e.g. hemisphere with radius r = 0,4 m), sound power level and sound pressure level are in this distance numerously equally big. Is the sound power level indicated in dB(A), are both of the following spellings acceptable: Lwa in dB or Lw in dB(A)“

Sound emission measuring on machines, Suvapro,Luzern

The practice – two worlds:

While the system’s operator who is in charge of occupational health protection has to know all details necessary on site, in order to protect each individual employee at his special workplace, the machine manufacturer can only test his own machine.

It is not possible for the machine manufacturers, and that is why they do not have to consider all ambience conditions in their sound limit measurement.

Machine manufacturer: sound emission of a single system

Operator: noise immission on employees

Conclusion

The sound pressure limit indicated by the machine manufacturer, referring to a single system, can be practically up to 10 – 15 dB(A) higher than the one measured by the operator at the workplace.

The sound pressure limit relevant to the operator will deduce always from the regulation of occupational health protection. These provide measuring the exposure at the workplace close to the worker’s ear (e.g. dosimeter).

The sound pressure limit indication by the machine manufacturer cannot be used one to one for evaluating for the ability of a system for the workplace. Further sound sources within the room are to identify and the entity is to consider. Sound measuring in existing workplaces can only give conclusions to the situation on site (various sound sources, room influence) and never to single machines.

A measurement of a system’s sound emissions at one workplace is technically not possible with average measuring instruments, because influential factors of the ambience cannot be excluded from the measurement. These measuring do usually never conform to the indications by the machine manufacturer.

Important: (The sound power level in a room becomes higher the more systems are operating at once.) In a room in which several systems are running, the sound power level will increase the higher the addition of all sound power levels in a room is. Sound limits cannot be used to calculate with them like with numbers, because there exists a logarithmic context.

Example: Machine 1: 80 dB(A) + Machine 2: 80 dB(A) = 83 dB(A)

Hint: Many people perceive the increase of sound level by 10dB(A) as doubling of noise. People notice lower frequencies as less penetrating than high ones.

Machines should be placed in a way the noise emissions are not turned towards the worker. Sound protection walls and special sound protection covers repress additionally.

Sources: BGHM – DGUV Information 209-023, Machine guideline 2016/42/EG

Seven aspects for noise optimization of your extraction system at the workplace

  • Choose the setup location of the filter and extraction system with a minimum distance of 2m from the operator.
  • If possible, place the filter and extraction system right behind other systems, machines or walls.
  • Adjust the suction power to your actual requirement! Often a reduction of the suction power by 10 % have a positive effect on the noise level und saves lots of additional energy.
  • Choose your capturing element optimally – sharp edges, high flow rates and turbulences cause unpleasant noise development and worsen the extraction result enormously.
  • Lead exhaust air in tubes, hoses or silencer away from your workplace. This reduces the noise level enormously and additionally the stress level of your coworkers due to whirled up dust on floor and walls.
  • Turn your filter and extraction system during breaks off or reduce the suction power – via foot remote, remote control, system programming, etc. (During breaks < 5min we suggest to reduce the suction power to a minimum instead of turning the blower off. This spares the blower’s engines).
  • Get advice from the TBH team.