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  • Stephen Biss

Ambient Conditions Change Baseline 0 on an IR Breath instrument


This video displays the function of the air blank and ambient fail systems on an IR evidentiary breath instrument such as the Intoxilyzer® 5000C (or 5000 as in this video) and the Intoxilyzer® 8000C (or 8000). In this experiment the room's ambient conditions have been artificially elevated to 50 mg / 100 mls by attaching a second simulator (at 50 mg/ 100 mls and 34C) to the breath tube inlet. Although the 5000 instrument is programmed to flag "Ambient Fail" at 20 mg/100 mls no such error message is produced. This is because the instrument can only compare an unacceptable ambient situation ( 50 mg/100 mls) against the baseline established when the instrument was first powered on (50 mg / 100 mls.) The instrument erroneously considers the 50 mg /100 mls as 00 mg /100 mls. The real danger of this phenomenon is that calibration checks become not reliable - and in this example the 100 mg /100 mls alcohol standard produces a calibration check of 51 mg / 100 mls. COBRA data from the weeks before and after a particular subject test may be very useful in flagging unusually low cal checks that possibly are being caused by ethanol or another chemical interferent in the room air (e.g. hand cleaners, paint, cleaning fluids). Unreliable cal checks do not cause erroneous subject test results but they do compromise the scientific reliability of the subject tests.

#ambientfail #truezero

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