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Verification of Digital Thermometer

Updated: Nov 8, 2022

Although not stated in the 8000C Training Aid, CFS scientists seem to be in agreement, that it is recommended that a NIST mercury thermometer be used, when using a digital simulator to confirm the display temperature. Please see the e-mail from Inger Bugyra below. Digital simulators include the Guth 2100, which police services generally use with Intoxilyzer 8000Cs.

[Please note that strictly speaking, using proper VIML terminology, this is not a "verification" that results in a "verification certificate". Rather it is an "inspection". I should not hav used the word "verification" in the title.]

The OPP historically has done a good job of regularly (every 6 months) checking digital simulator temperature displays, but other police services have not been as careful.

Digital temperature displays on simulators can lose their calibration over time. Please see the videos at my Youtube channel.

The slide referred to below was included in the Qualified Technician 8000C course re verifying digital simulators with a mercury thermometer. The topic is not referred to in the CFS 8000C Training Aid. Below please see an e-mail document (obtained by a Freedom of Information application) from Inger Bugyra. The e-mail is directed to CFS scientists and is dated May 26, 2010, respecting the scientist/8000C meeting of May 21, 2010.

E-mail to CFS scientists re use of NIST mercury thermometer
Document obtained pursuant to a Freedom of Information application

Under Bill C-46, section 320.31(1)(a), the Crown only benefits from "conclusive proof" if the following condition precedent is proven beyond a reasonable doubt. This condition precedent may be proven prima facie by a Certificate of a Qualified Technician and perhaps by QT evidence or hearsay, however, that prima facie proof is rebuttable with Interpretation Act "evidence to the contrary".

(a) before each sample was taken, the qualified technician conducted a system blank test the result of which is not more than 10 mg of alcohol in 100 mL of blood and a system calibration check the result of which is within 10% of the target value of an alcohol standard that is certified by an analyst;

It may be worthwhile to cross-examine the QT on whether or not the "system calibration check" was scientifically "reliable". If the digital temperature display indicating 34.0 +/- .05 degrees C. was not reliable, then the system calibration check was not reliable. Parliament has not chosen to enact a provision in 320.31 deeming the display on the simulator as "conclusive proof".

Please remember that the whole point in Parliament requiring a "system calibration check", is to compare the calibration of the Intoxilyzer, at time of use, against a "known" concentration, the alcohol standard in the simulator, maintained at a "known" temperature of 34.0 +/- .05 degrees C.

There is plenty of room in Section 320.31(1) litigation for such an argument, if the defence calls expert evidence from a metrologist.


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