Calculation and compensation units

Flowmeters provide measurement results according to process pressure and temperature values. It is often required that the measurement reflect the normal state. The task of compensation units is to make the necessary corrections. Especially in the case of invoicing use, it is important to know the flow rate precisely.

The flow rate of liquid fuels can be converted into mass flow rate by considering the temperature and calculating the density at the measured temperature.

Natural gas volume measurement is based on volumetric flow measurement. Due to compressibility, in addition to the volumetric flow rate measured, the pressure and temperature conditions at the time of measurement must be considered. The measured volumetric flow rate of natural gas is converted to the normal state (0ºC and 1.01325 bar). In accurate measurements, the compressibility factor is considered as well, since natural gas differs slightly from ideal gas by behaviour, especially at higher pressures.

Calculation methods used in the case of gaseous media:

  • ideal gas law
  • Redlich-Kwong
  • GERG 88
  • flow correction considering temperature, pressure and compressibility

Assemblies ready for installation are available

METRA ERW 700 determines the values for volumetric and mass flow rate, as well as for energy. To achieve high accuracy, the variables depending on the pressure and temperature are being constantly corrected.

The meters are delivered panel-mounted or as wall mounting enclosures ready for installation.