• Stephen Biss

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

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

When you watch this video, you will see two video segments at 19:34 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.

The problem is 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.

#ambientfail #reliability #tip

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