KAN position paper on EN ISO 8041 causes a buzz

EN ISO 8041 sets out requirements for vibration measuring instruments and describes their testing and calibration. The standard is required in the field, but cannot be applied in its current form at justifiable cost. For this reason, KAN has drawn up a position paper containing concrete proposals for improvements to be made during the revision of the standard..

EN ISO 8041 “Human response to vibration – Measuring instrumentation” specifies performance characteristics and tolerance limits for measuring instruments for determining the impact of vibration upon human beings. The standard also contains provisions for a hierarchical system of traceable calibrations and for tests ranging from pattern evaluation and periodic verification testing to in-situ checks.

EN ISO 8041 has an important function in the measurement of workplace vibration exposure. The EN ISO 5349-2 and ISO 2631-1 measurement standards specified in EU Vibration Directive 2002/44/EC, for example, specify/recommend the use of a measurement instrument to EN ISO 8041. In addition, numerous test standards for the measurement of vibration emissions make reference to this standard.

The current version of EN ISO 8041 is however in need of improvement in some points, and in the opinion of users cannot be used in practice without reservations. For this reason, Germany had already called in the past for this standard to be revised. CEN/TC 231 “Mechanical vibration and shock” shares the concerns presented by Germany and has also called upon ISO to revise the standard with consideration for its use in the field.

Results of the KAN discussion with experts

Expert representatives from all stakeholders in Germany met under the overall lead of the Commission for OSH and Standardization (KAN) in order to discuss the problems associated with the application of EN ISO 8041. The discussion showed clearly once again that the standard is needed for uniform testing and calibration of vibration measuring instruments. In the opinion of users, however, some of its requirements are not beneficial in practice, or can be implemented only at considerable cost. A need for improvement particularly exists with regard to the following points:

• The calibration devices for low-frequency whole-body vibration specified for in-situ testing are not currently available on the market. Although such devices could in principle be manufactured, this would be very expensive owing to the low production runs.
• The standard specifies periodic verification testing in order to ensure that the instrument continues to comply with the required specifications. This verification testing is extensive (the more so for multichannel devices), very time-consuming, and therefore very expensive for the operators of the instruments.
• In-situ testing by operators (1-point calibration and function testing) is not practicable for whole-body vibration, since a simple calibrator for 16 Hz does not exist, particularly for the mounting disc.
• The current version of the standard does not contain provisions governing dosimeters. Since a number of dosimeters are now available on the market, particularly for wholebody vibration, users require information for the selection of a suitable product; otherwise, a risk exists of the vibration exposure being underestimated.

KAN position paper as a basis for further action

As a result of the discussion with the experts, a position paper (pdf) was produced listing the problems with the standard and presenting concrete proposals for improvements. By means of this document, the points of criticism are to be brought to bear in the desired revision. In order to provide users with a transitional solution for uniform and appropriate application of EN ISO 8041 until the new version of the standard is available, the position paper also includes an abridged, practicable procedure for the verification testing of vibration measuring instruments.

The KAN position paper is also intended to provide motivation and to serve as a point of reference for more far-reaching practical guides for the users of the standard. DIN calls upon ISO to consider the details of the proposed improvements during revision of the standard.

Bettina Palka