Micro preparation of reference gas mixtures without compromising uncertainty

Gergely Vargha, EffecTech (GB)

EffecTech is an ISO 17025 accredited supplier of gravimetrically prepared Primary Reference Gas Mixtures (PRGM).  As a commercial supplier of the highest quality reference gas mixtures EffecTech is keen to continue to develop innovative technologies to improve preparation efficiency whilst maintaining the very low calibration and measurement capability (CMC) for which it has already been recognised through accreditation.
During the preparation of primary gas standards, efficiency can be increased by adding very small amounts of permanent gases, liquefied gases or gasified liquids using low volume technologies that guarantee no losses during this addition.  This also requires the use of low capacity micro-balances that are capable of measuring mass additions in the milligrams (mg) range with high precision.
During the planning stage of this research project key objectives were identified that needed to be fulfilled:

Despite these strict requirements a micro-injector system has been successfully developed. The system is completely leak free and at every step of the process the leak-tightness is under control. Liquids and gases can be added to the injector to within 1 or 2 mg of the mass required by the recipe. This is made possible by the use of a fine in-built needle valve to control the release of any excess amount of gas/liquefied gas.
With this newly developed device direct preparation of low µmol/mol or in special cases nmol/mol amount fraction mixtures can be accomplished without the need for pre-mixtures. Additions of 10 mg of a gas/liquid/liquefied gas can be made with an uncertainty less than 0.1% relative
This presentation shall demonstrate how such micro-injectors can be used to prepare reference gases of the highest metrological quality with remarkably efficiency.


Pen Profile

I have been working on the preparation of Primary Reference Gas Mixtures (PRGM) since 1978. For 23 years I was working in the Hungarian  National Metrological Institute (OMH), since 2002 I have been working in the UK. After spending 10 years at National Physical Laboratory I started to work at Effectech Ltd. in 2012 as a Principal Research Consultant.
The main focus of my work is to develop new methods and tools to improve the precision and efficiency both of the measurements and the preparation of the PRGMs.
I have developed plenty of mechanical tools special preparation, measurement and calculation methods and recently I have also developed a completely new, very promising cylinder passivation method called Performax® treatment that will be the topic of another presentation.


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