Met-AAM: Metrologisches Atemalkoholmessgerät

• Forschungsstelle: METAS
• Projektnummer: F-5232.30059

Schlüsselwörter (Englisch)

Breath alcohol analyser, MIR laser spectroscopy, OIML R126, General inspections, Demonstration

Kurzbeschreibung (Englisch)

The project “SI-Atemalkoholgenerator“ (F-5232.30018) revealed that the current available determination methods for ethanol in wet air are insufficient to test the wet generation meth-od according to OIML R126 with the necessary accuracy. Therefore, a suitable breath alcohol analyser is developed and validated in collaboration with EMPA. For testing the wet generation method according to OIML R126 the ethanol in wet air has to be determined with a precision of less than 0.1 % relative. A feasibility study in 2013 has shown that this precision is achievable with direct MIR absorption laser spectroscopy. The technology is now mature enough to realise such a precise breath alcohol analyzer.
The built-up metrological breath alcohol analyzer will allow METAS to test on the one hand the wet generation method according to OIML R126 in comparison with a SI-traceable gen-eration and on the other hand the capabilities of national metrology institutes. Futhermore, it will allow the test of evidential breath analyzer in the field during general inspection. For a statistical meaningful statement on the effect of the metrological regulation of breath alcohol measuring devices a precise instrument is of need. It will strengthen the confidence in the “Via Sicura” measure evidential breath alcohol test. Additionally the potential for compact breath alcohol analyzer will be demonstrated and the development of new instruments will be stimulated.

Projektziele (Englisch)

The objective of the project is the built-up and the validation of a metrological breath alcohol analyser with a precision in the determination of ethanol in wet air below 0.1 % relative.

Abstract (Englisch)

A metrological breath alcohol measuring instrument based on QC-Laser absorption spectroscopy at reduced pressure conditions has been built up. It fulfils the targeted metrological characteristics necessary for the comparison of different reference systems for the adjustment and calibration of breath alcohol instruments - wet references based on Dubowski versus dry gravimetrically prepared gas mixtures. All validated characteristics such as resolution, linearity, selectivity and insensibility to the main interferents water and carbon dioxide exceed the expectations. The goals concerning the extent of the validation as well as the automation of the measurement procedures have also been achieved within budget and schedule.

Umsetzung und Anwendungen (Englisch)

With the realisation of a comparative instrument with an unparalleled and unique resolution, linearity and insensibility to the main interferents water and carbon dioxide, it will be possible to compare divergent reference systems with sufficient accuracy. This will allow to investigate the cause for the bias and to render traceable the well-established wet generation method of representative reference gas mixtures to the SI.