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Rhode Island DUI Lawyer

What is the breathalyzer machine and how does it work?


The breathalyzer machine used in Rhode Island is the Intoxilyzer Model 5000. I have trained extensively on the Intoxilyzer 5000 and I am currently a U.S. DOT certified breath alcohol testing technician. Alcohol that is consumed shows up in the breath because it gets absorbed from the mouth, throat, stomach and intestines into the bloodstream. As the blood passes through the lungs, some alcohol moves across the alveoli (membranes of the lung’s air sacs) into the air. Thus, the concentration of the alcohol in the alveolar air is directly related to the concentration of the alcohol in an individual’s blood. The Intoxilyzer 5000 works on the theory of infrared absorption. The machine has a light source (light bulb) positioned at one end of the sample chamber. There are filter wheels at the end of the cylinder and on the other side of these filter wheels is a light receiver. The Intoxilyzer uses an infrared sensor to detect a specific wavelength of EM (Electromagnetic) energy absorbed by the alcohol molecule. A person will blow into a tube which leads to a breath sample chamber. The machine shines a light source (light bulb) through this sample chamber. The filter wheel spins at the other end of the breath tube chamber. The infrared light causes the alcohol molecules to “absorb” light at a particular frequency. Because the alcohol concentration in the breath is related to that in the blood, a calculation of the alcohol in a person’s breath is thought to be the equivalent of a calculation of the alcohol in a person’s blood. The ratio of breath alcohol to blood alcohol is 2100:1. This assumes that 2100 parts of alveolar air will contain the same quantity of alcohol as 1 part of blood. As the alcohol in the lung air is exhaled into the breathing tube, the machine captures a sample of the breath, measures the breath alcohol content and then uses the 2100:1 formula to convert it to the blood alcohol content.

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