This European Standard specifies the requirements and tests for the construction, performance, safety and conformity of conversion devices used to determine the energy of fuel gases described in the Table 1, including those of the 1st and 2nd families according to EN 437. The energy conversion device (ECD) considered in this standard consists of an energy calculator (EC) and is associated with the following devices and/or functions: - a volume conversion device (VCD) or a flow computer used as gas meter conversion, either conforming to EN 12405-1, or to prEN 12405-3, for high accuracy measurements; - a calorific value determination device (CVDD). Requirements for type approval tests of the devices, not included in the above-mentioned standards are described in appropriate annexes specified in Table 6. For the purpose of this European Standard, the term "volume conversion devices" (VCDs) includes flow computers (FCs). A single calculator may undertake the volume conversion functions for different metering lines.