COBRA of Low Cal Check Sequences

Tip 22: Study #duisimulator COBRA for clusters of low climbing cal checks at 3400.

low climbing cal checks
Simulation by S. Biss of Low Climbing Cal Checks in COBRA V

It's a lot of work, but if you obtain complete COBRA in its native raw text fomat or Excel format, you can sometimes find several clusters of cal checks below 90 for the same instrument and detachment. You need to "Unmerge" the data first if it is COBRA V. Next highlight the data (omit the headings) and make sure the data is sorted chronologically. Use the "Find" function in Excel to hunt for instances of the word "Tolerance". Specifically you are looking in COBRA V for "Calibration Check Out of Tolerance" That will enable you to find cal checks that are "out of tolerance" i.e. below 90 or above 110. Look for a series of stand-alone cal check sequences where the first cal check is well below 90 but then over the course of one or two stand-alone cal checks the result climbs above 90. One might infer from such data that the initial cal checks were done by the QT when the simulator had not yet reached operating temperature (Henry's Law at work). Check the time stamps. Consider how much time it takes for the simulator to warm up. Consider the context of solution change dates and times before and after.

Now check the indicated simulator temperatures. Are they all 34.00? Consider the quote in Tip 21.

Perhaps police in that detachment have succumbed to temptation to always enter 34.00 no matter the real temperature of the simulator. Perhaps police are not following their protocols. Perhaps police are running diagnostics and cal. checks while out of the breath room or without paying attention to the instrument displays.

Your expert or the CFS expert may draw the inference that there is a serious problem with QA and QC in the detachment or that the approved instrument or accessory equipment were malfunctioning. CFS may also suggest that ambient conditions were very cold, e.g. in a breath truck during a holiday RIDE programme. In the latter case, be ready to cross-examine on ambient conditions precedent to good evidentiary breath testing and on simulator heater response time.


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