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Metrology: gas flow rate measurement
Air humidity measurement • Temperature measurement • Liquid flow rate measurement
Gas flows rate measurement • Pressure measurement • Air velocity measurement
CALIBRATION
ACCREDITATION
N°2.1124
GAS FLOW RATE MEASUREMENT

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Calibration methods

Three methods are used depending on the ranges of flow rate:
 1 
Flow rates between 10 and
5000 cm3/h:
volumetric method which consists in determining the time necessary to transfer the air going through the device to be calibrated into a reference volume. The flow rate is calculated from the reference volume and the filling time.

 2 

Flow rates between 3 and 300 dm3/h:
Method which consists in putting in series the device to be calibrated with a laminar flow meter of Molbloc type.

 3 

Flow rates between 0.13 and 2030 m3/h:
Method which consists in putting in series the device to be calibrated with one or several Venturi nozzles functioning at sonic velocity and used as references. The flow rate is calculated from the characteristics of the reference nozzles.

The sonic nozzles are put in parallel in order to adjust
the flow rate to the wanted value.


Calibration conditions

The minimum calibration programme includes for the volumetric gas flow meters 6 flow rate values repeated once (i.e. 12 measuring points) and for every other types 5 flow rate values repeated once (i.e. 10 measuring points).

For devices functioning at a steady flow rate point, the latter will be repeated twice (i.e. 3 measuring points).

The calibration is performed at ambient temperature.


Fields and best calibration uncertainties

Flow meter

FIELD UNCERTAINTY
Pressure Gas Flow rate
100 kPa
to
600 kPa		 dry air *,
humid air **,
nitrogen		 10 cm3xh-1
to 5 000 cm3xh-1		 ±8x10-3qvr
3 dm3xh-1
to 300 m3xh-1		 ±3.1x10-3qvr
dry air*,
ambient air,
humid air;**		 0.13 m3xh-1
to 2030 **m3xh-1		 ±5.1x10-3qvr
* limited to 600 Nm3xh-1
** on demand for soap bubble flow meters and water guard meters
*** for an upstream pressure of the device to be calibrated around 100 kPa
qvr : reference volume flow rate


Price list

You can download a document including this description: calibration in gas flow rate measurement..

 
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