3.1.2 (c) 2. Specification of gas quality parameters (GCV, Wobbe-index) and costs of conversion for network users in case gas is outside these specifications

Quality control

The Transmission licensee measures the parameters of natural gas quality on the Hungarian transmission system and can provide the information for system users with specific contracts in case the demands exceed the basic service.

Specifications of the natural gas quality

The parameters must comply with the requirements of the GET VHR annex 11 (standard MSZ 1648:2000). The following chart contains the requirements:

Sign of the gas group



Standards of the inspection methods



Wobbe-index MJ/m3

45,66 – 54,76

36,29 – 41,58

MSZ ISO 6976


31,00 – 45,28


27,94 – 40,81


The System User is responsible for the injection of natural gas of sufficient quality. In case of injecting natural gas of insufficient quality, point of the Network Code shall apply.


Quality Accounting Rules (QAR)

The transmission licensee publishes the averages of the NCV values weighted by quantities according to the system exit and entry points. That gas quality (NCV) value is a suggestion for shippers and users for using those values in their contracts, and for any energy content conversions on a specific exit or entry point.

The QAR regulates the assignment of chromatograph sample flows to network points and the gas flow dependent replacement order of chromatograph sample flows.

The QAR includes the following:

  • The chromatograph locations, gas flow directions, and sample flow codes;
  • Assignment of chromatograph sample flow codes for delivery points and gasflow dependent substitutions, NNO, gas group;
  • Classification of the gas flow dependent replacement order, network neighboring operator and natural gas type according to each network point
  • Yearly weighted average calorific value (NCV), which is the weighted average of the daily average NCVs and it is calculated by each network point. The yearly weighted average calorific value is calculated by the transmission licensee for the period between 1st of January and 31st of December.

Determination of the quality by the network points:

  • The gas quality parameters are measured by the chromatographs installed on the gas transmission network.
  • The daily gas quality is the 24-hour average value of the gas quality parameters measured by the chromatographs
  • After every gasday the transmission licensee assigns to the entry and exit points the code of the chromatograph corresponding to the gas flow of the previous day. In case the measured chromatograph data are not available, a replacement chromatograph determined by QAR must be assigned to the affected entry or exit point. In case any replacement chromatographs are not available the data measured by a laboratory must be used.
  • Gas quality of network points created from the combination of elementary points is calculated by the average (weighted by quantity) of the affected elementary points.​​