Breath Alcohol Instrument Calibration

The proper breath alcohol instrument calibration is important in order to maintain confidence in the test results.  When performing testing under Dept. of Transportation regulations, DOT mandates that a calibration adjustment be conducted following a failed accuracy check.  That is also best practice for non-regulated alcohol testing as well – a calibration adjustment should be performed when an instrument fails an accuracy check.  When calibration adjustments and accuracy checks are not properly conducted and documented, it may be difficult to enforce subsequent consequences.   Therefore, proper calibration plays a crucial role in the alcohol testing process.  Knowing how to successfully troubleshoot calibration conundrums is vital.

AlcoPro’s technical support department receives countless phone calls on a daily basis from customers in need of calibration assistance for various Alco-Sensor models.  Typically, we find that the two most common reasons for an incorrect calibration are: the instrument is out of temperature range; and the operator is not following the calibration procedure correctly.

Most Alco-Sensor instruments require that the instrument be within a narrow temperature range before the calibration procedure can be performed.  For example, the Alco-Sensor IV instrument temperature for calibration must be between 23°C and 27°C.   (See the owner’s manual for the specific temperature requirements for your Alco-Sensor  model). If the instrument’s temperature is displaying below the temperature threshold, we recommend holding it in your hands for a short period of time, placing it in direct sunlight to warm, or placing it in a shirt pocket.  However, we do not recommend introducing an artificial heat source such as ovens or blow-dryers.  If the instrument reading is above the temperature range we recommend allowing it to cool in an air conditioned room for short period of time.  Refrain from the use of refrigeration or cooling systems to cool the instrument.

The calibration procedure is specific to each Alco-Sensor instrument.  Most Alco-Sensor models require that the instrument be put into “calibration mode” before proceeding with the calibration.  The procedure for placing the instrument in calibration mode varies with each instrument, and is intentionally non-intuitive to prevent unintentional and/or tampering with the calibration.

Here are some common, instrument specific calibration procedure mishaps:

Alco-Sensor III – people sometimes confuse the different model types.  The newer Alco-Sensor III (with the red eject slide mechanism) requires the user to manipulate the READ and SET buttons to put it into “calibration mode” before actually turning the calibration screw, while the previous version does not require this step.

Alco-Sensor FST –the operator introduces the calibration gas standard into the FST during the “auto-blank” process of the calibration, instead of waiting for “cal” to appear on the display (that is, the operator introduces the gas too early and as a result the calibration fails).

Be sure to familiarize yourself with the calibration procedure described in the owner’s manual, or you may visit our calibration web page.

Please call our repair department to speak with a technician if you are having difficulty with the calibration of your Alco-Sensor; we may be able to help you fix the problem over the phone.  You may also send your instrument in for a free service evaluation.  Simply fill out our Repair Form and include with your instrument.