Noise emitted by machinery

Noise as governed by Directive 2006/42/EC

Noise is an intrinsic feature of the machine that every manufacturer is required to consider during the design phase; poor consideration of this aspect can lead to the creation of a product with high noise risks.

The issue is addressed in Requirement 1.5.8 of Annex I and reads as follows:

“Machinery must be designed and constructed in such a way that the risks arising from the emission of airborne noise are reduced to the minimum level, taking into account technical progress and the possibility of having means to limit noise, in particular at source. The level of noise emission may be assessed by reference to the comparative emission data of similar machinery”.

The Directive requires us to design the machine considering the risks related to noise because prolonged operator exposure to high noise levels is a cause of operator fatigue and stress, permanent damage to the auditory system as well as deafness and secondary hazards caused by communication difficulties and/or difficulties in hearing warning signs.

The directive does not refer to operator exposure to machine noise, but rather to noise emission as an intrinsic characteristic of the same which, if detected under predetermined conditions, can be treated as a technical feature of the product put on the market.

The manufacturer is responsible for the risks related to the noise produced by the machinery

On the other hand, the operator’s exposure is closely linked to the use of the machine and depends on the mode, the installation environment, the characteristics of the workplace, the time of use of the machine during the working day and the noise produced by other sources present in the environment (theme dealt with in Directive 2003/10/EC).

Certain noise emission limits are set for some categories of machinery by Directive 2000/14/EC modified by 2005/88/EC which regulate the noise of the same if intended to operate in an open environment where the noise emission of the machine assumes a fundamental importance for the purposes of environmental noise pollution.

The Machinery Directive does not impose limits on the acoustic emissions produced by machines but requires the utmost attention right from the design to reduce them to a minimum and this leads the manufacturer to have to carry out a careful analysis of the risks related to the issue of noise; on the other hand, a silent machine is a product with superior market value.

How to declare the noise value?

Directive 2006/42/EC also deals with the reporting of machinery noise data from specific tests; this information is provided by requirement which quotes under “u”:

“Each instruction manual must include the following information about airborne noise emissions:

  1. the A-weighted sound pressure level at workplaces if it exceeds 70 dB(A); if it does not exceed 70 dB(A), it shall be indicated,
  2. the maximum value of C-weighted instantaneous sound pressure at workstations if it exceeds 63 Pa (130 dB compared to 2 μPa),
  3. the A-weighted sound power level emitted by the machine, if the sound pressure level of the A-weighted emission at the workstations exceeds 80 dB(A).”

As can be seen, the declaration of the machine noise values is required in. the user manual.

These values must always be tested by a phonometric Test Report which must be attached to the technical file of the machine.

The test report, shall either report all measurements taken than assure the “repeatability” of the results. 

It should therefore include: technical test conditions, environmental conditions and uncertainties related to the reported data.

As you can see, as the emission level of the machine increases, the attention to the theme rise as well and more specific information is required.

In particular, if the machine sound pressure at the operator’s position (or other specific positions) exceeds 80 dB(A), the sound power statement is required, This parameter formally characterizes the machine from the acoustic point of view, not being linked in any way to the distance of the operator.

How to measure noise?

There are two standard reference sets that provide standard procedures for performing sound tests:

  • EN ISO 1120X series with X = [0 – 5] that allow to characterize the machine in terms of sound pressure level at the operator’s position or in other specific positions;
  • EN ISO 374X series with X = [0 – 7] which allow the characterisation of the machine in terms of sound power (to comply with point 3 of Requirement letter u).

In both cases, the standards allow us to conduct tests with different degrees of complexity (Precision method = grade 1, Engineering method = grade 2, Survey method = grade 3).

Higher values are associated with higher complexity of testing.

The rules provide guidelines for the identification of measurement uncertainties. The uncertainty shall be stated in the phonometric report and in the manual according to the provisions of EN ISO 4871:2009 (Declaration and verification of noise emissions from machinery and equipment).

The Acoustics Sector of Advolo consists of 2 Competent Acoustics Technicians (TCA). It is specialized in the acoustic design and implementation of Noise Test Report for different types of industrial machinery according to the requirements of Directive 2006/42/EC.

Please feel free to contact us for any need!

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