The new hydrodynamic test field at PTB is operational. The currently achievable measurement uncertainties for flow and quantity measurements of flowing liquids are lower than half of their previous values. Therewith the facility is a world-wide inimitable primary standard for liquid measurements.
Concerning the measurement of flow rate and totalized mass or volume of flowing liquids, industry and research as well as medicine, environment and consumer protection call for specificities which to be guaranteed demand PTB, in turn, to represent the appropriate units with expanded measurement uncertainties below 0,02 %. Internationally, the best current values lie between 0,04 % and 0,05 %.
The new hydrodynamic test field utilizes water as a test fluid. It will achieve the required uncertainty of 0,02 % in liquid flow in the flow range from 0,3 m3/h to 2100 m3/h. This follows from the projected results of the measurement uncertainty budget as well as from the acceptance tests of the major components and parts. The crucial preconditions were already created with the measurement-technical concept of the facility. The facility combines two different-type reference systems based upon totally different measurement principles: a gravimetric reference comprising three weighing systems (for 30 t, 3 t and 300 kg, respectively, maximum load) and a geometrically verified volumetric reference (a 250-liter compact pipe prover), which are functionally interconnected via the water flow section. Through appropriate comparative measurements with both systems it is possible to recognize and evaluate the effects of hitherto hardly realistically assessable parameters on the measurement uncertainties. In this field such a concept has been realized for the first time. Furthermore various other innovative partial solutions have been implemented to achieve the aspired measurement parameters. Novel measurement-technical and design concepts were developed, e.g., for the weighing system, the flow diverters and the calibration procedure for the pipe prover.
Exact verification of the measurement uncertainties is currently one of the key activities of the scientific and experimental assignments at the hydrodynamic test field. Substantial research activities will also deal with integrating optical methods to measure velocities in the liquid measurements. Beyond that intensive investigations will concentrate on developing transfer methods and standards that are independent of the medium being measured.
[Translate to English:] Rainer Engel,
Fax: (05 31) 592-61 32