Why does a laser optical calibration of large flow meters make sense?

Hot tapping. Source: Vattenfall

The process of demounting measurement instruments implies an interruption on the supply and high costs. Therefore, after an initial manufacturer's calibration, large heat and water flow meters are used during decades without any interruption. Additional measuring errors are generated while demounting and during posterior calibration of the measurement instruments on a test facility. These errors are generated due to the difference between operational and calibration conditions on the test facility, for instance temperature, inflow and flow rate. The measurement errors can produce significant economic consequences (incorrect billing) leading to a deterioration of customer relations.

In-situ calibration without supply interruption

Laser optic flow measurement in situ

ILA GmbH in collaboration with OPTOLUTION and the German National Metrology Institute (PTB-Berlin) has developed a new and inovative laser optical measuring technique. This technique permits on-site calibration of flow meters without having to interrupt operations or demounting the measurement instrument. For this purpose, the velocity profile in the pipe is acquired with the help of a LDV system, then the corresponding volume flow rate is calculated. The calibration of the installed flow meter is performed by comparison with the laser optical transfer standard. For this method, the German National Metrology Institute (PTB) has certified a measurement error of +/-0,6% (under reference conditions).

Our laser optical technique has been tested by the German National Metrology Institute (PTB) and it is certified by TÜV Rheinland.


  • Acquisition of the real measurement errors of all flow meter's components on site.
  • No interruption on the supply during installation and measurement TÜV Rheinland certified service (also safety approval).
  • Potential of use in legal metrology.
  • Significant potential for saving, through customer friendly accounting and accurate cost transparency, reduction in balance sheet discrepancies.
  • The key-hole socket can be used for periodic measurements and other types of inspections.

Applications and limitations

  • Rotationally symmetric flow conditions (otherwise, multiple path measurements) DN 150 to ca. DN2000, PN25 (40), T.max 130 °C, Steel pipes
  • Transparent fluids (Drinking water, pre-purified effluents, district heating/cooling, light gasoline, steam, gases)


  • VATTENFALL Europe Wärme AG (DN 150, 200, 250, 400, 500)
  • EnBW Stuttgart (DN 800)
  • Fernwärme Wien GmbH (DN 400)
  • Energie Wasser Bern (DN 150, 250, 300) 

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52428 Jülich | NRW

E-Mail: rd@ila.de
Telefon: +49 2461 690430



ILA_5150 GmbH

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52066 Aachen | NRW

E-Mail: info@ila5150.de
Telefon: +49 2419 5789814