For test installations FMG developed a special positive displacement meter for small flows. This unique meter has special shaped impellers which makes the meter pulsation free.

The meter has 2 independent measuring chambers in one housing (both comparable). The minimum capacity per chamber is 0,15 m3/h and the maximum capacity per chamber is 10 m3/h. Operated in parallel the maximum capacity is 20 m3/h.

As the volume per rotation is small, the rotational speed at low flows is still relatively high and as such enough pulses for a highly repeatable measurement are produced.

For master meters used in test facilities, not the accuracy of the meter, but the uncertainty is the most important value. Build in the test facility the deviation of the meter (accuracy) is corrected to zero by the software. Uncertainty is the only important value for the quality of master meters  used in a test facility.

To proof the uncertainty of the FMR-M20 master meter, it was calibrated against the primary standard of the  Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig Germany.