Directive 2004/22/EC of the European Parliament and of the Council of March 31, 2004 on measuring instruments is also referred to as MID.
This Directive applies to devices and systems with a measuring function, such as water meters, gas meters, heat meters, measuring systems for measurement of quantities of liquids other then water, automatic weighing instruments, etc. This Directive is a specific Directive in respect of requirements for electromagnetic immunity in the meaning of Article 2(2) of Directive 89/336/EEC that continues to apply with regard to emission requirements.
MID applies to devices and systems with measuring functions. It establishes the requirements that all devices and systems have to satisfy if they are to be placed on the market and/or put into use. The measuring instrument certificate attests not only the conformity to requirements but also the compliance with Directive 89/336/EEC.
To achieve the objectives of the Directive, we need to understand the terms used therein::
Measuring instruments must be certified in stringent compliance with all Annexes to the Directive. Besides the general requirements, requirements specific to the country where the measuring instruments are going to be sold and put into use are developed.
Each product item should also be stamped with a special marking that includes the CE marking and the supplementary metrology marking. The marking affixed by the manufacturer (that is solely responsible for that marking) contains such information as technical specifications, product group, intended use, etc.
Every certification of measuring instruments involves maintaining relevant technical documentation that renders the design, production and operation of the measuring instrument. This information enables assessment of the conformity of the instrument with relevant requirements of this Directive.
The technical documentation should be sufficiently detailed to ensure:
Furthermore, the technical documentation should include a general description of the instrument, its conceptual design and manufacturing drawings and plans of components, sub-assemblies, circuits, manufacturing procedures, technical diagrams, etc. It also contains results of design calculations, examinations, a list of the standards and/or normative documents.