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New experimentation and water meter test rig put into operation


In May 2004, the new experimentation and water meter test rig (EWZP) of PTB's department "Liquid flow" could be put into operation. It extends the measuring range of the Hydrodynamic test field towards small flows and is especially designed for the control and metrological testing of domestic water meters.

The most important metrological characteristics of the test rig are:

  • Volumetric flow: 0.01 … 40 m³/h
  • Reference method: gravimetric with 150 kg balance and flow diverter
  • Working pressure: 5.3 bar for direct pump operation
    3.2 bar for operation with constant head-tank
  • Temperature stability: ± 0.05°C during an individual measurement
    ± 0.1°C during a measurement series
  • Expanded measurement uncertainty: 0.05 %

The test rig was put into operation within the scope of a key comparison with five test rigs from verification authorities of Baden-Wuerttemberg, Brandenburg, North Rhine-Westphalia, Saxony and Thuringia. The comparison group was composed of two multiple-jet meters and one oscillating piston meter in a flow range between 0.025 … 5 m³/h. These first results obtained on the new PTB test rig were extremely satisfying. The measurement deviations determined by means of the comparison meters were in very good agreement with those of the other test rigs. It is important to point out the excellent reproducibility of the measured values, which can be seen from the standard deviations having been reached for the performed measurement series. These were clearly smaller for the PTB measurements and generally amounted to only half to a fifth of the values reported by the other test participants. This proved the good measuring stability of the test rig ab initio.

View of the new PTB experimentation and water meter test rig

Figure 1. View of the new PTB experimentation and water meter test rig

The test rig will be used primarily for the following tasks:

  • Testing of domestic water meters within the scope of approval procedures
  • Elaboration of new, efficient and internationally recognised test procedures in order to replace the water meter approval tests which are required in the provisions presently valid (MID, OIML, CEN) and are very time-consuming.
  • Development of transfer standards, especially for the in-situ testing of domestic water meters. A research project on this subject is currently in progress between the PTB department "Liquid flow" and the verification authorities.

With the described experimentation and water meter test rig, PTB has for the first time an efficient and multi-purpose measuring facility for the field of domestic water meters available. Under the aspect that, within the scope of the implementation of the European Measuring Instrument Directive (MID), the requirements on measuring depth and accuracy have increased, especially for water meters, these new measurement possibilities are essential preconditions to remain a privileged partner in the field of legal metrology and to be able to play an active role in the future shaping of the national and international legal framework.

Contact person:

Gudrun Wendt, FB 1.5, E-Mail: gudrun.wendt@ptb.de