Plus petite des trois cuves PvTt

The COFRAC audit from end of 2023, regarding the scope nr 2-1294, enabled Aérométrologie to position itself at the level of the best reference laboratories on the air flow meter calibration on the range of 1,94 mg.min-1 < qm  < 38,8 g.min-1

This extension of our accreditation has a dual objective: to improve uncertainties and optimize the master calibration duration.

Concerned devices

Indeed, Aérométrologie extended its accreditation scope nr 2-1294 to the air flowmeters using the PVTt bench.

Are now concerned:

  • Calibrated orifice calibration,
  • Nozzle calibration under a service pressure,
  • Mass flow meter calibration,
  • Molbloc + molbox calibration,
  • Any precision flowmeter calibration,
  • If the flowmeter works by suction or if it includes an inlet / outlet to allow a compressed air alimentation.

We have still the possibility to emit a judgment, to be confirmed in regards of the wished value.

Masters used

The masters used are composed by three tanks, whose volumes are calibrated and connected to national standards in order to ensure that they, despite the volume being fixed, do not drift over time.

These three tanks are equipped with different sensors, in order to monitor the pressure and temperature inside.

Method explanation

The dynamic PVTt method consists in observing and evaluating the evolution of the gas mass in a standard volume by measuring pressures, temperatures, humidity and time.

After 2 years of development and validation, our extension to our current accreditation has been obtained and it now allows us to cover a flow range from 1.5 cm3/min to 35 dm3/min (expressed at 0°C and 101325 Pa) with an uncertainty that can go down to 0,1% of the measured flow.

We thus open our technical capabilities of calibration to standard flowmeters of type Molbloc and to the mastery of a fundamental method based on the law of perfect gases, which for memory is PV=nRT, where

  • P : Pressure (Pa),
  • V : Gaz volume (m3),
  • n : the quantity of material (mol),
  • R : the universal constant of perfect gases,
  • T : The absolute temperature (K).


It is therefore by a primary method that we determine the flow rate and not by a comparison with a reference standard, in the same way that pressure balances also implement a calibration by primary method.

Calibration by the PvTt method allows to reach the following extended uncertainties, appearing on the scope of accreditation nr 2-1294 Rév13 :

  • Enlarged uncertainty between 9,5×10-4 × qm and 1,25 × 10-2 × qm (influenced by the device in calibration)
  • On the following air mass flow range: 1,94 mg.min-1 < qm < 38,8 g.min-1

Aérométrologie is now ready to take in charge of your most accurate flowmeters, in particular to calibrate Molblocs, while allowing a short and controlled calibration duration, as well as an extended uncertainty comparable to the best French laboratories.

Our service by appointment also allows you to optimize the downtime over a week.


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