Sätt att kalibrera och kontrollera en apparat för bestämning av koncentrationen av ett specifikt ämne i en persons utandningsluft

摘要

A method in calibrating or checking an apparatus for determining in a person's exhalation air the concentration of a specific substance is disclosed. The apparatus comprises means for passing exhalation air along a free measuring length, and means for supplying air of a predetermined composition to the measuring length to produce an air flow along the length. A mixture of the substance and water in a specified concentration thereof inder instantaneous evaporation is injected into the air when supplied to the measuring length. The concentration of the substance and the concentration of water vapor in the air flow along the measuring length is determined. The substance gas flow and the water vapor flow are calculated, and the ratio thereof is compared with the specified concentration of the mixture.