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    Measuring Instruments directive


    The new Measuring Instruments Directive (2014/32/EU) has been published. This will come fully into force on 20 April 2016.



    The Directive applies to the devices and systems with a measuring function defined in the following instrument-specific annexes MI-001 to MI-010 (i.e. not all measuring instruments are within the scope of the Directive);

    MI-001 - Water meters

    MI-002 - Gas meters and volume conversion devices

    MI-003 - Active electrical energy meters

    MI-004 - Heat meters

    MI-005 - Measuring systems for continuous and dynamic measurement of quantities of liquids other than water

    MI-006 - Automatic weighing instruments

    MI-007 - Taximeters

    MI-008 - Material measures

    MI-009 - Dimensional measuring instruments

    MI-010 - Exhaust gas analysers



    A measuring instrument must meet the essential requirements laid down in Annex I, applicable to all instrument types, and in the relevant instrument-specific Annex of the Directive. The general requirements cover the following aspects;

    Allowable errors (including specifications of the intended climatic, mechanical and electromagnetic environment the instrument has been designed for)



    Discrimination and Sensitivity




    Protection against corruption

    Information to be borne by and accompany the instrument

    Indication of result

    Further processing of data to conclude the trading transaction

    Conformity evaluation

    The directive contains several requirements concerning software. Namely, software that is critical for the metrological characteristics shall be identifiable, shall be secured, shall not be inadmissibly influenced by other software and shall be adequately protected against accidental or intentional corruption. It is the manufacturersí decision how the software might meet the MID requirements, but a guide has been published by WELMEC to assist manufacturers, examiners and inspectors. 

    A technical file shall be produced that renders the design, manufacture and operation of the measuring instrument intelligible and shall permit an assessment of its conformity with the appropriate requirements of the Directive. Depending on the assessment method chosen to demonstrate compliance with the Directive, the technical file may require more or less information ñ for example; details of manufacturing procedures to ensure consistent production, descriptions of electronic devices with drawings, diagrams, flow diagrams of the logic and general software information, design calculations, EC-type examination certificates.

    With respect to the electromagnetic compatibility of the instrument, the immunity requirements are specified in the relevant instrument-specific annex of the MID. The emissions requirements, however, are as specified in the EMC directive 2004/108/EC.