Volumetric Measurement of Gas Volume & Calibration of Gas Volume
Opposite to measurement of temperature or pressure, the accurate measurement of gas volume (and gas flow rate) requires a comprehensive knowledge of the physical behaviour of gas. For example, mass flow meters don’t measure gas volume but the gas flow rate by the change of resistance of two heated wires. However, this change of resistance is dependent on the gas composition (gas mixtures), temperature, humidity etc..
RITTER manufactures drum-type gas meters which volumetrically measure gas volume. With this measurement principle, the gas volume is measured directly thus eliminating the mentioned factors falsifying the measurement results. The measurement accuracy of all RITTER drum-type meters is ±0.5% of reading across the full measurement range. Furthermore, the RITTER gas meters are made from superior thermoplastics for measurement of even highly aggressive gases.
Obviously, the calibration of such highly accurate gas meters is of utmost importance. RITTER developed and manufactures a calibration system for gas flow rate and gas volume based on the technology of Sonic Nozzles. This measurement principle allows calibration uncertainties of down to 0.3%. Because there are no expendable or moving parts, the calibration results are long-term stable (nozzles > 2 m³/h 10 years, < 2 m³/h 5 years). Furthermore, the system is maintenance-free.
 Dr.-Ing. Ritter Apparatebau GmbH, Germany