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More Problems with the Draeger Alcotest 9510 Breath Machine

Posted Wednesday, June 20, 2018 by Andrew Charles Huff

Washington state’s new breath test machine the Draeger Alcotest 9510 uses two sensors to measure alcohol content in a breath sample: An infrared beam that measures how much light goes through the breath, and a fuel cell that measures the electrical current of the sample. The results should be about the same and within a small margin of error – usually within a thousandth of a decimal point. If the results are too far apart, the test will be rejected.

However, reports have found that under some conditions the breath machine can return an inflated reading – a result that could also push a person over the legal limit. One reason is the apparent lack of adjustment made by the machine of a person’s breath temperature. Breath temperature can fluctuate throughout the day, but can also wildly change the results of an alcohol breath test. Without correction, a single digit over a normal breath temperature of 34 degrees centigrade can inflate the results by six percent – enough to push a person over the limit.

The Washington State Patrol still claims the machine should correct the breath temperature to prevent false results. According to the WSP, the quadratic formula corrects warmer breath downward. But the code doesn’t explain how the corrections are made and the corrections may be insufficient if the formula is faulty.

Issues with the code notwithstanding, Washington chose not to install a component to measure breath temperature, according to testimony in a 2015 hearing, and later confirmed by Draeger. The Washington State Patrol said they “tested and approved the instrument that best fit our business needs,” and believes the device can produce accurate results without the breath temperature sensor.

The code is also meant to check to ensure the device is operating within a certain temperature range set by Draeger, because the device can produce incorrect results if it’s too hot or too cold. But the report said a check meant to measure the ambient temperature was disabled in the state configuration.

When asked, a Washington State Patrol spokesperson would not say if the breathalyzer was configured to allow breath tests outside its operational temperature range, saying only that the device “has been tested and validated in various ambient temperatures.”

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