Process and device for measuring a gas medium with a chemical sensor
AssigneeTesto AG
InventorsAxel Broedel, Thomas Springmann, Reinhold Munch, Armin Bader
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Abstract
The invention relates to a process and a device for measuring a gas medium with a chemical sensor that has a nominal measuring range. The chemical sensor is exposed to a gas mixture consisting of sample gas stream and dilution gas stream. In order to ensure that the chemical sensor always works within its nominal measuring range, the dilution ratio is readjusted. According to the invention, the dilution ratio is determined by substance concentration measurement of a defined substance component.
Claims18
A process for sampling and introducing a sample of an unknown gaseous medium to a chemical sensor, the gaseous medium potentially comprising a particular gaseous substance, the chemical sensor responsive to the presence of the particular gaseous substance to provide a first electrical signal indicative of its concentration within the sample and having a nominal measuring range, said process comprising the following steps:
- a) taking a sample of said unknown gaseous medium;
- b) taking and mixing a dilution gas with the sample of the unknown gaseous medium to obtain a mixture thereof in accordance with an adjustable dilution ratio, said dilution gas comprising at least one known substance component of a predetermined concentration of said dilution gas;
- c) measuring the concentration of said one known substance within said mixture to provide a second electrical signal indicative thereof;
- d) introducing said mixture to the chemical sensor and operating said sensor to provide the first electrical signal;
- e) adjusting in accordance with said second electrical signal said dilution ratio;
- f) readjusting in accordance with said first electrical signal said dilution ratio to maintain the operation of the chemical sensor within its nominal measuring range;
- and
- g) evaluating said first and second electrical signals to provide a measure of the concentration of the particular gaseous substance in a manner to compensate for the adjustable dilution ratio.
Apparatus for taking a sample of an unknown gaseous medium potentially with a particular gaseous substance and providing a measure of the concentration of the particular gaseous substance, said apparatus comprising:
- a) a mixing chamber;
- b) means for taking a sample of the unknown gaseous medium into said mixing chamber;
- c) means for introducing a dilution gas along with said sample of the unknown gaseous medium into said mixing chamber to provide a mixture thereof in accordance with an adjustable dilution ratio within said mixing chamber, said dilution gas having at least one known substance component of a predetermined concentration of said dilution gas;
- d) a chemical sensor coupled with said mixing chamber to receive therefrom said mixture and to provide a first electrical signal indicative of the concentration within said mixture of the particular gaseous substance, said chemical sensor having a nominal measuring range;
- e) at least one further sensor to provide a second electrical signal indicative of the concentration of the one known substance component;
- and
- f) control means responsive to said first and second electrical signals for operating said introducing means whereby said dilution ratio is adjusted in such a manner that said chemical sensor operates within said nominal measuring range.
Dependencies are inferred from the claim text.