The 23M (FMTB 650) and 88M (FMTB-2500) are compact Transfer Provers using air under atmospheric conditions starting at 9cfh (1.0m3/h) up to 88,000cfh (2,500m3/h) for the FMTB-2500. The 350M FMTB 10000 also uses atmospheric air and up to 6 Master Meters achieving flowrates as low as 18cfh (0.5m3/h) to as high as 353,00cfh (10,000m3/h). The transfer provers are designed to calibrate to a high level of accuracy in the shortest possible test time. All FMTBs are equipped with high quality sensors and instruments whose measurement results are traceable to international standards like VSL (formerly NMi).
The FMTB works in a unique way. Using digital signal processing with a sample rate of 250 KHz it permits a start/stop time measurement on any pulse transition for both the Meter Under Test and the reference meters. In this way a stream of test data is collected and analyzed in a short time producing reliable values.
The FMTB series is suitable for testing several meter types in a large flow range. This makes the FMTB series attractive for manufacturers of gas meters and test laboratories, and also for companies with many field installed gas meters that have to be checked periodically.
The uncertainty of the test bench is calculated according to ILAC-P14:01/2013. Taking into account all the uncertainty sources, the test facility can be delivered with a maximum total uncertainty of 0.25% for flow rates over 35cfh (1m3/h) and 0.35% below 35cfh (1m3/h) which is well inside the limits of 1/3 of the Maximum Permissible Error (MPE) according MID or OIML.