Measurement principles for gas quantity and quality
Article 7
1. In respect of the measurement principles for volume, energy and gas quality, the adjacent transmission system operators shall ensure that: (a) the details of the measurement standards applicable at the interconnection point are established; (b) the transmission system operator responsible for the installation, operation and maintenance of the measurement equipment is identified. This operator shall have the obligation to make all information and data in respect of the measurement of gas flows at the interconnection point available to the other adjacent transmission system operator(s) in a timely manner and at a frequency specified. 2. The installation, operation and maintenance of measurement equipment at an interconnection point shall take into account the technical requirements imposed by national regulations on the adjacent transmission system operators. 3. The adjacent transmission system operators shall agree on measurement principles which shall at least include: (a) a description of the metering station including measurement and analysis equipment to be used and details of any secondary equipment that may be used in case of failure; (b) the gas quality parameters and volume and energy that shall be measured, as well as the range and the maximum permissible error or uncertainty margin within which the measurement equipment shall operate, the frequency of measurements, in what units and according to what standards the measurement shall be made as well as any conversion factors used; (c) the procedures and methods that shall be used to calculate those parameters which are not directly measured; (d) a description of the method of calculation in respect of the maximum permissible error or uncertainty in the determination of energy transported; (e) a description of the data validation process in use for the measured parameters; (f) the measurement validation and quality assurance arrangements, including verification and adjustment procedures to be agreed between the adjacent transmission system operators; (g) the way data, including frequency and content, is provided among the adjacent transmission system operators in respect of the measured parameters; (h) the specific list of signals and alarms to be provided by the adjacent transmission system operator(s) who operate(s) the measurement equipment to the other adjacent transmission system operator(s); (i) the method of determining a correction to a measurement and any subsequent procedures that may be necessary in a temporary situation where the measurement equipment is found to be or have been in error (either under-reading or over-reading outside of its defined uncertainty range).This transmission system operator shall take appropriate action to end this situation. (j) rules that shall apply between adjacent transmission system operators in the event of failure of the measurement equipment; (k) rules that shall apply between the adjacent transmission system operators for: (i) access to the measurement facility; (ii) additional verifications of measurement facility; (iii) modification of the measurement facility; (iv) attendance during calibration and maintenance work at the measurement facility. 4. If the adjacent transmission system operators fail to comply with their obligations provided for in paragraphs 1 and 3: (a) the transmission system operator in control of the measurement equipment shall be responsible for the installation, operation and maintenance of such equipment and for providing the other transmission system operator with the data regarding the measurement of gas flows at the interconnection point in a timely manner; (b) the European standard EN1776 ‘Gas Supply Natural Gas Measuring Stations Functional Requirements’ in the version applicable at the time shall apply.