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BACtrack S50 Operating Instructions

Below are basic operation guidelines for the BACtrack S50 breathalyzer. For more detailed instructions and explanations, please read the BACtrack S50 Breathalyzer Owner’s Manual.


IMPORTANT: Users must wait 20 minutes after eating, drinking, or smoking before blowing into the S50 breathalyzer. Failure to wait 20 minutes can provide inaccurate test results and possibly damage the sensor.

    • Before Starting 

      Insert a mouthpiece into the slot. The side with the wider diameter goes into the slot, and your mouth goes on the side with the smaller diameter. It is recommended to insert a fresh mouthpiece before each test.

    • Step 1

      Press the Power button. The total number of tests performed since the last service is briefly displayed and then a countdown sequence begins.

    • Step 2

      When the countdown approaches 10, begin to inhale a deep breath. 

    • Step 3

      When the countdown reaches zero, the READY light will flash and two beeps will sound. Blow firmly and continuously for five full seconds. While a user is blowing, the S50 will sound a continuous tone. Keep blowing until two beeps are heard.

    • Step 4

      When finished taking a breath sample, the S50 will circle the outer LCD fields while analyzing it.

    • Step 5

      Once the sensor has analyzed the breath sample, the estimated BAC value is displayed.

The displayed result is an estimate of the test subject’s BAC.

The test result will be displayed for 10 seconds. Then the S50 will beep five times before powering off. If the BAC reading is over 0.05%, the red WARN lamp will illuminate and a rapid beep alarm will sound.
A breath alcohol tester cannot determine the exact BAC in the blood of the test subject. Correlation between Breath Alcohol Content and Blood Alcohol Content depends on many factors, such as temperature and health conditions. Therefore, only use this device as a tool to screen for the presence of alcohol.
Many people consider a 0.02% or greater a positive test for alcohol in “zero tolerance” screening. Most states have 0.08% as the legal BAC limit for tasks such as operating a motor vehicle. Some states prohibit driving commercial vehicles or any vessel with a 0.04% BAC or higher. Many states and countries prosecute individuals for driving under the influence at any level.

Powering Off

To turn the power off at any time, leave the unit alone. Not touching the power button for 30 seconds will trigger it to automatically shut itself off with minimal effect on the life of the battery.


    • This indicates that the battery power is low and that the batteries should be replaced. 

    • If a user does not blow a sufficient breath sample, the LCD will display “FLO." Press the Power button to restart the countdown cycle and retest. Be sure to blow firmly and continuously for five full seconds while testing. 

    • If there is no breath sample blown within 10 seconds, the LCD will display “Out.” Press Power to restart the countdown cycle and retest.

    • The "CAL" display indicates that the unit requires recalibration or maintenance. Please refer to Calibration section of our Support Center to find out how to get your unit calibrated.