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Reliability: Cal Checks in the Context of Earlier & Later Ambient Fails

Updated: Sep 13, 2022

Tip 47: A calibration check using a wet-bath simulator containing alcohol standard is not reliable if information is missing about air blanks associated with the cal checks.


  1. Intoxilyzer 8000

  2. Dry Gas Alcohol Standard 45 mg/100mls

  3. Vodka


  1. To study air blanks (blank tests) and control tests in the context of an elevated zero on an IR approved instrument.

  2. Is the ambient fail system compromised? (appears as 000 even though adverse ambient conditions)

  3. Is the control test system compromised? (appears as 000 even though 45 mg/100mls alcohol standard)

  4. To study the phenomenon illustrated in "Ambient Conditions Change Baseline 0 on an IR Breath instrument - Disappearing Alcohol" respecting an Intoxilyzer 5000, and now apply the phenomenon to an Intoxilyzer 8000.

When you watch this video, you will see two video segments at 19:34 (Intoxilyzer screen time) (06:00 on video) and 19:37 with stand-alone cal checks that do not produce ambient fail or purge fail exception messages, yet the calibration checks are strange. In both cases 045 alcohol standard produces a 000 result. Are these cal checks reliable? It would appear that zero has been set by the IR instrument above 45 mg/100mls and so the cal check results are each 000. This isn't supposed to happen if the IR instrument has a properly functioning ambient fail system.

We can infer that zero must have been compromised in an earlier sequence. Video segnents at 19:35 and 19:38 shed light on what happened, as would video segments before 19:34.

Disclosure of printouts from a single stand-alone cal check and the cal checks associated with a pair of subject tests, doesn't tell the whole story of whether or not the cal checks are reliable and whether or not ambient alcohol was absent from the room.


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