To operate the Intoxilyzer 500, turn it on and use the small button to see the available operation modes. Press the large button to select the desired mode. Have the subject breathe into the long end of the mouthpiece to get a blood alcohol content reading.
Make sure that the Intoxilyzer 500 is on by pressing the power button. The unit is designed to make BrAC mode, or breath alcohol concentration, the user's first option, since this is the most common mode used for field sobriety tests conducted by law enforcement officers. Fit a new disposable mouthpiece to the top of the unit before having the subject breathe into it. Once enough breath has been captured, the screen reads "Wait. Analyzing..." Shortly after that, the subject's three-digit blood alcohol content reading should appear.
After use, remove and discard the mouthpiece. The screen should read "Ready" at this point. If the screen shows an error message such as "suck back detected" or "insufficient sample," repeat the procedure. This time, press the large button on the front of the unit while the subject is breathing into the mouthpiece to capture the breath manually. The Intoxilyzer can also be used in zero tolerance mode, which delivers either a positive or negative result instead of a numerical value.