The European measuring instruments directive (MID)

PCN Europe talked to Günter Ruhl, industry specialist for water and waste water at KROHNE Messtechnik, one of the market leaders in industrial process measuring technology, about the implications of the European measuring instruments directive.
What is the measuring instruments directive? The Measuring Instruments Directive (MID) 2004/22/EC is a European Directive that covers a number of different measuring instruments for custody transfer measurement. The aim of the MID is to create a single market in measuring instruments for the benefit of manufacturers and consumers across Europe. Especially when money is changing hands, accurate measurement is required so that the parties involved in the transaction are treated fairly. Same applies to measurements that are executed to protect public health (e.g. exhaust meters). There can be a 10 year transitional period after the MID became effective on the 30th of October 2006. This means that measuring instruments can be put in use by existing EEC and national type approval certificates. Annexes define how the instruments can be declared as compliant to MID. Notified bodies are authorised to carry out testing, and the certification issued by one of them shall be accepted within the whole of the EU.
To which instruments does the directive apply? The Directive applies to the devices and systems with a measuring function defined in the following instrument-specific annexes MI-001 to MI-010.
• 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 In the case of KROHNE as manufacturer of flow measuring instruments, the following annexes apply: MI-001, MI-002, MI-004 and MI-005. These cover the measurement of gases and liquids other than water as well as the measurement of heat and potable water.
How can compliance with MID be achieved? For instruments affected by the MID and brought to market after 30.10.2006, manufacturers e.g. first need to turn to one of the notified bodies in the EU. They will examine the design and declare that it meets the requirements of the directive. The notified body will then issue the appropriate EC type examination certificate. In a second step KROHNE has chosen to obtain a quality assurance of their production, in which a certified body inspects the production process and equipment of the manufacturer for the instrument concerned. The products can then leave the factory with a declaration of conformity with the relevant appendix of the MID. KROHNE has achieved conformity in this way for water meters (MI-001), for gas meters (MI-002) and heat meters (MI-004) and owns EC type examination certificates. For these instruments, only the device itself needs to be compliant not its installation.
What about MI-005: “Measuring systems for liquids other than water”? All designs of measuring systems for liquids other than water, which are to be used for legal purposes, require certification under the MID. The range of systems can include: measuring systems on pipelines, road tankers, for (un)loading of ships, road and rail tankers, fuel dispensers but also liquified gases or foodstuff like milk etc. This part of the MID concerns a system, all instruments applied need to provide their individual MI 005 test certificate, but compliancy needs to be achieved for the system as a whole, and an EC examination certificate needs to be obtained for each system. The responsibility for the measuring system as a whole resides with the party that takes charge of the complete project not with the individual instrument manufacturer. Krohne decided to offer complete MI 005 measuring systems with specific flow meters from their portfolio, in well defined combinations with selected instruments relevant for these measuring systems. This allows the customer to create their own suitable modular installation. For the combinations proposed, examination certificates have already been achieved, so the party responsible for the complete system can avoid administrative struggles. After final acceptance and the official calibration, installations like these are ready for operation.