Rotary gas meters are characterized by compact dimensions and extended measuring range. They ensure high accuracy, even under low or irregular gas flow conditions. The rotary gas meters utilize the rotary type positive displacement principle of operation which makes volumetric measurements by displacing finite volumes of gas.

The positive displacement occurs within a cavity formed between the meter’s internal housing and its rotating impellers. The counter-rotating impellers turn as a result of pressure drop across the meter’s inlet and outlet created as downstream gas is consumed. The rotating impellers separate the flowing gas into small, finite, volumes and are counted using a mechanical index.​