Technical assistance for users of measuring instruments

In some countries organizations have established themselves to provide users of measuring instruments with technical assistance. Two examples of such organizations are given below.

1.4.7.1. The EXERA (France)

This chapter, which deals with the analysis of metrological requirements, would be left unfinished if no mention was made of the EXERA, one of the few associations which work to support industrial metrology.

The EXERA is a non-profit-making association, an amalgamation of companies and organizations that are major users of instruments and systems of measurement, regulation and automation. Since its foundation, in 1970, its purpose has been to produce and circulate original information and to provide its members with assistance when they need to express their requirements, to choose, to install and to operate materials and systems.

The EXERA is first and foremost a club; it is a privileged meeting place for users, where specialists (over 500) can freely exchange what information about what experience has taught them, as well as information about instruments and systems.

This club acts, in essence, through its members by organizing the technical evaluation of materials. It also initiates the writing of guides about the choice of material in the different technical areas and, at the same time, does its best to develop a constructive dialogue with manufacturers.

In a spirit of partnership, groups of users are constituted so that they can take responsibility for their needs and they can better express and defend them in front of manufacturers. This enables the users and the manufacturers to obtain more elements of explanation on investments and technological trends. There are technical commissions about automation, instruments, analyzers, measurements and systems for the tests, etc.

In 1982, the EXERA signed an agreement of international cooperation with two other organizations of users:

– the SIREP (Britain); and – the WIB (the Netherlands).

These two other associations have members in other industrialized countries, for example, the USA, Canada, Japan, Finland, Sweden, Belgium, Switzerland, etc.

The main features of the agreement, which ultimately concerns more than 100 large companies, are:

– the full-scale and well-balanced exchange of assessments of instruments and surveys, which are all written in English;

– the acceptance of common principles regulating the procedures of evaluation and the presentation of the documents;

– the harmonization of the work programs;

– the gradual adjustment of the formalities regulating the testing of materials.

Altogether, there are about 90 members in the three associations; 40 of the members belong to the EXERA, among them are: CEA, CGE, EDF, GIAT, IFP, L'OREAL, PECHINEY, RENAULT, TOTAL, etc. At present, approximately 80 reports are distributed annually by the three associations. In December 1991, the SIREP, the WIB and the EXERA were officially recognized by the European Organisation for Conformity Assessment (EOTC) as “Agreement group”. For more information, see www.eotc.bc or www.exera.com.

1.4.7.2. VDI/VDE-GMA (Germany)

In Germany an organization similar to EXERA is the Society for Measurement and Automatic Control GMA (Gesellschaft Mess- und Automatisierungstechnik).

This organization is a joint organization of the Association of German Engineers VDI (Verein Deutscher Ingenieure) and the Association for Electrical, Electronic and Information Technologies VDE (Verband der Elektrotechnik, Elektronik und Informationstechnik).

The GMA is a network of technical competence in metrology and other fields of activity. It combines expertise of institutions such as the German National Metrology Institute (PTB), the German Calibration Service (DKD), the German Institute for Standardisation (DIN), the International Organization for Standardization (ISO) and several industry associations and societies.

GMA activities include:

– the promotion of the exchange of information between industry, public authorities and scientific institutions;

– the organization of congresses, conferences, symposiums, etc. to promote the flow of information concerning new processes and developments;

– the preparation of publications, recommendations, guidelines, etc. to improve understanding;

– the scientific preparation for standardization;

– the national and international representation in the field of measurement and automation controls;

– the publication and promotion of technical and scientific literature;

– the support of education and post-graduate training.

In common technical committees, honorary experts of industry, research and science cooperate in different fields of metrology. Each committee is focused on specific branches of metrology. These committees produce newly-developed or up-dated technical documents. These documents are first presented as drafts. Views and comments of potential users are evaluated and the documents are modified before they are definitively published.

The guidelines published by VDI/VDE-GMA describe standards, e.g. in metrology. These metrology documents define procedures for users of measurement instruments (see the following table).

Metrological level Guidelines, documents and standards National Metrology Institute

(PTB) DKD accredited calibration laboratory

National DIN standards or DKD guidelines International EN or ISO standards

EA documents Optional:

In-house calibration laboratory Measurement and testing

equipment Product

VDI/VDE guidelines DKD guidelines

EA documents

Table 1.3. Metrology literature used in Germany

In the VDI/VDE guidelines there are three series dealing with the treatment of measuring equipment:

The series VDI/VDE/DGQ 2618, “Inspection of measuring and test equipment – instructions to inspect measuring and test equipment for geometrical quantities”, contains general considerations and determinations, as well as information on the expression of uncertainty in measurement. In separate documents there are procedures for calibration and surveillance of specific-measurement instruments. An example of such papers is the paper about the procedures for “Callipers for external, internal and depth dimensions”.

Another series, the VDI/VDE/DGQ/DKD 2622 guidelines, deals with

“Calibration of measuring equipment for electrical quantities”. Again, along with a general introduction including information on the measurement uncertainty, there are separate documents defining the calibration of specific, electrical measurement instruments. An example is the calibration procedure for electrical oscilloscopes.

The third series, VDI/VDE 2617, is entitled “Accuracy of coordinate measuring machines – parameters and their reverification”. The calibration, the acceptance and the surveillance of coordinate measuring equipment is defined in separate documents. This series is used as a base for the development of a new ISO standard on coordinate measuring machines.

More detailed information is available at the GMA secretariat in Düsseldorf, Germany (e-mail: [email protected]).