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Product category: Engineering Education, Resources and Standards
News Release from: AV Technology
Edited by the Engineeringtalk Editorial Team on 10 April 2001

Did you know about the European Noise
Directive?

The new European Noise Directive for equipment used outdoors becomes effective from July 3rd of this year and has caught many manufacturers 'on the hop'.

The new European Noise Directive for equipment used outdoors becomes effective from July 3rd of this year and has caught many manufacturers 'on the hop' The shattering of the peace on a Sunday morning by high pitched hover mowers and strimmers is an all-to familiar scenario, as are the teeth chattering reverberations from pneumatic drills as we walk down the High Street

There is no doubt that noise in the environment is becoming a major issue and this new Directive is part of an overall programme to control noise emissions which can have long term affects on health and general well being, both for operators of equipment and bystanders.

Directive 2000/14/EEC came into effect in July 2000 and must be implemented in the UK by July 3rd 2001, becoming mandatory by January 2002.

It replaces legislation from nine separate Directives and covers 57 categories of equipment from lawn mowers to construction machinery, from concrete breakers to wheelie bins and from lift trucks to mobile platforms.

Although it specifically excludes equipment for transporting goods or people by road,rail or air as well as military and emergency vehicles, it does cover equipment such as refuse collection vehicles, vehicle refrigeration equipment, excavators, dump trucks and bull-dozers.

The main requirements for this new directive are for a 'responsible person' to measure the noise levels of their equipment and to affix labels showing the 'guaranteed' noise levels of each machine.

A ' responsible person' is defined as either the manufacturer or the manufacturers' authorised representative.

Where neither of these is based in the European Community, the onus falls on the person placing the equipment on the market or putting it into service to ensure its compliance.

Of the 57 listed categories, 22 are currently subject to specified maximum noise limits while the remainder are only required to have noise levels labels affixed.

This segregation has evolved historically from available data and appears to have little logic behind it.

For instance, lawn mowers are subject to noise limits whereas leaf collectors and hedge trimmers are not.

As more data is collected and assessed, then more equipment will become subject to noise limits.

Of the 22 categories, 11 are already covered by existing Directives and these will be repealed and superseded by the new Directive.

There is currently a twin track approach for ensuring compliance with the Directive, dependent on the equipment classification.

In both cases the manufacturer prepares the relevant technical documentation, including details of construction, and carries out noise tests as defined in Annex III of the Directive in order to arrive at a guaranteed noise level.

This must take into account the uncertainties due to production variation and other relevant factors.

The manufacturer then issues a declaration of conformity and all machines must be labelled accordingly.

For the 22 types of equipment subject to noise limits, Notified Bodies (approved by UKAS-UK Accreditation Service) must be involved in the verification procedures.

Their role is to audit the technical documentation and testing procedures, ensuring compliance with the Directive, and issue a report accordingly.

In addition they have an ongoing involvement with the manufacturer to monitor the production process.

The technical documentation must consider all the factors which influence the noise produced by the machine and it must be a 'live' document, whereby the notified body is informed of all 'on-going' changes in design and production.

The Notified Body must be satisfied that the test facilities, instrumentation and test staff meet the requirements of the Directive.

The test site must meet the requirements laid down in the Annex III according to ISO 3744.

All instrumentation must also meet these and be calibrated regularly by a UKAS accredited laboratory For the remaining 35 types the manufacturer takes full responsibility for the testing and uncertainty calculations.

Although the fundamental requirements of the Directive appear relatively straightforward, actually unravelling all the relevant information is causing a certain amount of confusion and bewilderment -especially when it comes to understanding the calculations of the uncertainties involved.

Stockport based AV Technology are currently one of only five UK companies who have Approved Laboratory status for testing under the old style directives and are in the process of applying for Notified Body status for the new Directive.

The company, which offers broad base consultancy and testing services in areas of noise, vibration, stress analysis and thermal imaging, has been instrumental in taking the lead in developing the procedures necessary to demonstrate compliance, working closely with the DTI in the process.

As well as having broad experience in conducting testing in these areas, they also have extensive expertise in the statistical evaluation of the results.

As Mike Hewett of AVT points out: "We have found that many companies are struggling with the new Directive.

They are unclear on which construction factors influence noise levels and are perplexed by the uncertainty calculations.

By offering a practical approach based on our hard won experience in noise assessment we can save companies considerable time and effort by helping them produce the relevant technical files, set up the testing procedures and interpret the results.

If required we can also carry out noise testing on their behalf." Each category of equipment is tested in working or 'simulated working' conditions.

Most of the criteria for these have been drawn up by Manufacturers Associations in consultation with regulatory bodies, operating on a European or even Worldwide basis - believe it or not there is Wheelie Bin Manufacturers Association! For companies manufacturing outside Europe, the requirements of the Directive relating to the assessment of production processes must still be met and AVT are currently working with several major manufacturers in the US and Asia.

This involves visiting the plants, and assessing the testing procedures and production processes.

A key role for AVT is interpreting the results from the noise tests and applying suitable statistical models to provide acceptable guaranteed noise levels that are representative of the equipment.

The Directive requires that machines are labelled with a 'guaranteed' sound power level which must take into account the factors affecting uncertainty in the measurements.

(Uncertainty of measurement is fundamentally different to measurement error.

There is always a margin of 'doubt' in any measurement.

Answers to both 'How big is the doubt ?' and 'How bad is the doubt?' need to be addressed to quantify the uncertainty).

There are two main sources of uncertainty - that of the measurement process itself arising from variations of measurement values taken from one machine, and that of the variations of results from different production machines.

The guidelines for the Directive stipulate that a minimum of five machines should be tested to give a representative cross section.

The assessment process does not end with the initial testing of machines.

The Directive is clear that the measurement procedure should be an on-going process in order to ensure changes do not occur in the life time of any manufacturing process.

The manufacturer must therefore involve the Notified Body in the production process to assess an on-going conformance in a manner agreed between the manufacturer and the Notified Body.

The manufacturer is obligated to assess the uncertainty in any measurements and although the Directive does not stipulate how this is achieved, there are guidelines which give examples on how this can be calculated.

The final specified noise level must take into account both measurement and production uncertainties.

In order to arrive at a guaranteed noise level which has the minimum required 95% confidence level, a correction factor K is applied to the average sound power determination.

As Mike Hewett concludes: "It is clear that this new Directive places strict controls on manufacturers of equipment for outdoor use.

Exactly how effective this will be remains to be seen and final arrangements for enforcement have yet to be agreed. Request free introductory details about products from AV Technology ...

It would appear that the legislation has crept up on manufacturers and, given the short time before this becomes mandatory, we are working round the clock to help our clients meet the deadlines.".

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