Archive for May 6th, 2005

How Breathalyzers Work (and Why They Don’t)

Friday, May 6th, 2005

Did you ever wonder how breathalyzers work? There is a website which will give you a pretty fair idea. But first, let’s clear up some confusion….

There are many different kinds of “breathalyzers” — or, more accurately, there are many kinds of breath testing devices. The first of the modern breath testers, manufactured by Smith and Wesson many years ago (yes, that Smith and Wesson), was called the Breathalyzer. Since then, various manufacturers have recognized the growing market and come out with their own models, bearing such names as Intoxilyzer, Intoximeter, DataMaster, AlcoSensor, Alcotest and so on; most of these products have been produced in different model versions, such as the Intoxilyer 4011, 5000 and 8000.

To deal with the confusion, the term “breathalyzer” came to be used as a generic term for any breath testing instrument. (To confuse things further, a German company — Draeger — bought the rights to the Breathalyzer brand and have sometimes used that name in some of their models.)

Most of these are evidentiary machines — that is, larger machines generally kept at the police station whose test results are used in evidence. Others are smaller, handheld units carried by officers in the field; generally called PBTs (preliminary breath tests) or PAS (preliminary alcohol screedning), these are less accurate and are usually used as a field sobriety test to help determine whether to arrest a suspect.

The original Breathalyzer operated using a wet chemical method of analysis, employing a disposable glass ampoule of chemicals. Although still occasionally found in law enforcement, this relatively primitive technology was replaced in later machines by infrared spectroscopy, gas chromatography or, mainly in handheld units, fuel cell analysis; a couple of the more recent machines use a combination of infrared and fuel cell.

Now that this has been cleared up, you might want to visit the following sites to understand the actual workings of these gizmos:

Chemical (the Breathalyzer)
Infrared spectroscopy (the Intoxilyzer)
Fuel cell (the Alcosensor)

Note: Gas chromatography is rarely encountered anymore, as it was primarily used in the discontinued Intoximeter 3000.

Note #2: To further understand why these machines aren’t nearly as accurate as law enforcement would have you believe, visit a few of my previous posts:

Breathalyzers — and Why They Don’t Work
Breathalyzer Inaccuracy: Testing During the Absorptive Stage
Breathalyzer Inaccuracy: Post-Absorptive
Breathalyzer Inaccuracy….It Gets Worse
“Close Enough for Government Work”
Why Breathalyzers Don’t Measure Alcohol
How to Fool the Breathalyzer
Breathalyzers and Radio Frequency Interference
Breathalyzers: Why Aren’t They Warranted to Measure Alcohol?

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