When to Calibrate a Breath Alcohol Instrument.
Frequently our repair technicians receive calls asking the circumstances around when to calibrate a breath alcohol instrument. We recently received a question about performing a calibration adjustment on an Alco-Sensor instrument: “Do we need to re-calibrate the Alco-Sensor when replacing the batteries?”
An interesting question, we thought. The answer is “no”. Changing the battery in your breath alcohol instrument in no way alters the software or hardware configurations that control the calibration of the instrument.
It is important to remember that Intoximeters requires a calibration adjustment only if an accuracy check on the instrument has failed; that is to say, only as needed. A set schedule for a calibration adjustment is not required by the Intoximeters Quality Assurance Plan.
So what is an “accuracy check” and how does that differ from a “calibration adjustment”? An accuracy check is a procedure to test the instrument to determine if it is reading a known sample of dry gas–known as a standard– correctly. This is similar to placing a known weight onto a bathroom scale to see if it measures the correct weight (e.g., 10 lbs). If the instrument fails the accuracy check then a calibration adjustment needs to be completed.
Continuing with our bathroom scale example, if the scale did not correctly measure the weight (10 lbs.) then one would turn the calibration screw on the scale until the scale indicated the correct weight. A calibration adjustment, then, is a procedure to “turn the screw” on the Alco-Sensor device until the correct reading is observed. Of course, the actual calibration adjustment procedure will vary depending on the specific model of Alco-Sensor in question.
A common misconception is the notion that a calibration adjustment needs to be completed on a set schedule—every day or week or month. Although other manufacturers may require periodic calibration adjustments, Intoximeters does not. Remember, a calibration is required only if an accuracy check is not successful. This means that it could be months or even a year before an instrument needs to be calibrated.
However, according to Intoximeter’s Quality Assurance Plan (QAP), an accuracy check must be performed at least every 30 days and after a positive breath alcohol confirmation test. Depending on the volume of testing in your program you may also perform accuracy checks more frequently, such as every week. A good practice is to perform an accuracy check before performing the first test of the day; this will provide further confidence in your test results should a positive test on a subject ever be legally challenged.
The important thing is to have in place a protocol for accuracy checks—including proper documentation in the form of an accuracy check/calibration logbook.
Please call us or use our Instant Chat feature on our website if you need to talk with one of our service technicians about accuracy checks or calibrations.