Project DUNAMET no. D36. Tomáš Valenta Czech Metrology Institute. Project DUNAMET no. D36. the inter-comparison among Czech Republic ( CMI ) Austria ( BEV ) Hungary ( OMH ) and Slovak Republic ( SMU ) took place from May 2004 to August 2004
Czech Metrology Institute
Czech Republic (CMI)
and Slovak Republic (SMU)
The axial turbine gas meter G650 was used for the comparison.
(ELSTER –AMCO Group)
The turbine gas meter G650 was tested in each laboratory by air in horizontal position.
It was necessary to use the upstream straightening pipe that was long at least 5x DN and the downstream straightening pipe that was long at least 3x DN.
The reference pressure from the turbine gas meter was measured from the output “pr”.
The reference temperature from the turbine gas meter was measured in the distance (23)x DN downstream of the turbine gas meter.
The HF pulse emitter A1S(the pulse number 4579,88 pulses/m3) was used for the tests.
The calibration had to be performed in the laboratory where the temperature was from 19,5°C to 23,5°C. No oil lubrication was used.
The turbine gas meter was tested in 8 flow rates:
1000 m3/h, 800 m3/h, 650 m3/h, 500 m3/h, 400m3/h, 300m3/h, 200 m3/h, 100 m3/h.
Error of the meterwas determined. The Erroris value which shows the relationship in percentage terms of the difference between the volume indicated by the meter and the volume which has actually flowed through the meter, to the later value.
where E is the error of the meter
Vi is the indicated volume by the meter (m3)
Vc is the real volume which has actually flowed through the meter (m3)
Determination of the reference value
To determine the reference value tree different approacheswere used.
Mean:Mean is the arithmetic average of a set of numerical data.
Median:Median is the middle value of an ordered set of numerical data.
Weighted mean error (WME):
If in a series of observations a statistical weight (1/u2) is assigned to each value, a weighted mean y can be calculated by the formula:
xi are values of errors of meter in different laboratories in one flow rate
u (xi) are uncertainties U(k=2) of errors of meter in different laboratories in one flow rate
Flow ratein the meter
Weighted mean error (WME)
0,93Project DUNAMET no. D36
Slovak Republic (SMU)
Czech Republic (CMI)
All participants were successful. All determined errors of meter with their uncertainties U(k=2) in every flow rate cover the reference values Mean, Median and Weighted Mean Error.
THIS PROJECT CAN BE REPEATED AMONG EUROMET COUNTRIES IN 2006.
Note: I would like to coordinate quick and simple inter-comparison. That is why the supposed time to make calibration and to deliver the meter to next laboratory will be only 1 week.
The form „PROPOSEDEUROMET PROJECT“
will be sent to everybody by e-mail.