I hope u r asking about the enthanol in alcohol.. . There are two means of electronically measuring the breath alcohol concentration. Onemethod is by using an infrared and the other method is a fuel cell. Infrared Cell Alcohol strongly absorbs infrared energy at mainly two wavelengths namely 3,4 microns and 9,5 microns. 9,5 microns is referred to as the primary wavelength in the measurementof ethyl alcohol, or ethanol, the alcohol that is present in alcoholic beverages. Other substances absorb infrared energy at 3,4 microns therefore absorption at 9,5 microns, the primary wavelength, is used to determine alcohol concentration. In the infrared cell used to measure the alcohol concentration an infrared beam is passed through thebreath/alcohol mixture and detected by an infrared detector.The greater the concentration of alcohol in the breath sample the greater the amount of infrared light thatis absorbed (Lambert-Beer) The process of analysis of a breath sample for alcohol by infrared cell as follows: 1. The breath sample is captured in the infra-red cell 2. Infrared energy from the source passes through the breath sample. The alcohol in the breath sample absorbs some of the infrared energy. 3. The energy absorbed is related to the amount of alcohol present. 4. The reduction of infrared energy is detected and measured by the infrared detectorthe amount of reduction being proportional to the concentration of alcohol in the breathsample. Fuel Cell In the fuel cell an electro-chemical reaction between alcohol and oxygen produces an electric current proportional to the concentration of alcohol in air. The process of analysis of a breath sample for alcohol by the fuel cell is as follows 1. The breath sample is introduced to the fuel cell 2. The alcohol in the sample is chemically oxidized at the anode3. At the same time, oxygen (from the atmosphere) is chemically reduced at the cathode. 4. A current flow, proportional to the concentration of alcohol, is produced between the two electrodes. DRAGER ALCOTEST 7110 The Drager Alcotest 7110 uses two means of measuring the breath alcohol concentration. One measurement is performed in an infrared cell and the other ina fuel cell. Other substances will also produce a voltage at the terminals of the fuelcell and therefore the purpose of the fuel cell is to detect the presence of anysubstance other than alcohol. Should there be another substance present then thereading between the fuel cell and the infrared cell will differ. If the differenceexceeds 5% then the measurement process is stopped and no reading is displayed or printed. An indication of the presence of an interferent is indicated. . --------------------------------------------------------------------------------. Page 2 . Measurement Process After the instrument self tests and zero tests, the breath sample is introduced into the instrument via a delivery tube. From the delivery tube the sample enters theinfrared cell and is analysed. A small portion of the breath sample in the infraredcell is taken into the fuel cell. That portion of the breath sample is analysed by the fuel cell. The instrument does two whole processes automatically. The two results are compared and then a second self-test and zero tests take place, and then theresult is displayed and printed out. The instrument self-checking process takes place continually while the instrument is in use. If any of the self-checkingprocesses detect a fault, or one result is not confirmed by the other, the instrumentwill indicate that a fault has been detected and will automatically abort the analysis.The instrument also aborts the analysis if a self or zero test fails. Operating the equipment After being switched on, the instrument takes approximately 15 minutes to warm up duringwhich period the testing is inhibited. After warm up the testing is started and details entered via the keyboard. After the operator information has been entered the instrument automatically pumpsambient air