Behind the Wheel - August 10, 2005

[skidmark]

ASD vs Datamaster

The police in British Columbia use two tools to detect and charge impaired drivers. One is an Approved Screening Device (ASD) used at the roadside, and the other is the BAC Datamaster C which is used after the subject registers a fail with the ASD. Datamaster testing is conducted in the detachment rather than at the roadside.

The most commonly used ASD is the AlcoSensor IV DWF. It is based on a fuel cell that creates electricity from the alcohol on the test subject's breath. The more alcohol that is present, the stronger the current that is produced. The device then equates the current strength with the alcohol concentration and displays a result. From 0 to 49 mg% it shows digits, from 50 to 99 mg% it shows the word WARN and 100 mg% and above it shows FAIL.

If the word FAIL appears, the officer now has reasonable and probable grounds to believe the driver's ability to drive is impaired by alcohol and may make the breath demand to test the driver further. If the demand is made, the driver is compelled to accompany the officer for testing using the Datamaster.

The Datamaster is an infrared spectrometer. A controlled sample of breath is introduced into a test chamber and infrared light is passed through it. The light is absorbed in proportion to the amount of alcohol in the test subject's breath. By measuring the amount of absorption, the sample is positively identified as ethyl alcohol and then the amount present is determined.

A minimum of two separate samples of breath are necessary for a proper analysis using the Datamaster. If both samples are 100 mg% or more, the driver will be charged under section 253(b) of the Criminal Code for driving with a blood alcohol content over 80 mg%.

Both instruments are equally precise, with an error of +/- 10 mg% and are checked for accuracy every 2 weeks.

[GoreD]

Interesting info, cna't say i have ever even seen either of these, i just don't usually dink and drive. I guess you cn't give us any tips on how to cheat the machines eh. Oh well just don't do it is the best route i guess. It's a good thinkg nobody get's mad for drinking anfd computing :) :beer

[skidmark]

If the officer using them is following guidelines, there really is no way to cheat the instruments. In fact, messing around trying to do so is likely to result in a charge for failing to provide a breath sample, which carries the same penalty as impaired driving.

[rattle]

I still can't understand why if there can be a readout of the BAC from 0 to 49 mg there is only a warn from 50 to 99.

Does a warn almost always result in a 24 hour? Even say if for example you BAC was only 51 mg% which would be below the legal 80 mg%?

[skidmark]

A driving prohibition in BC under section 215 MVA generally gets issued for BAC's in the warn and fail ranges. If you can show you are under 50, the prohibition is terminated.

The instrument is programmed to give numbers from 0 to 49, the word warn for 50 to 99 and the word fail from 100 and up.

If it put it in calibration mode and use it, I will get numbers regardless.

[rattle]

Every ‘expert’ that I have heard from all seem to agree that a normal drivers ability to operate a motor vehicle will have a BAC of over 100 mg%. The legal 253 CC limit is 80 mg%. But 215 prohibitions are handed out at any readings over 50 mg%? Section 215(2) is worded that a peace officer may serve a notice of prohibition if they have grounds to believe that a driver’s ability to drive a MV is affected by alcohol. There is no definition of what affected is. Subsection (6) does state that if the BAC is less than 50 mg% the prohibition is to be terminated.

Doesn’t make sense to me.

Guess I will just have to stick to cabs when going out for a couple of drinks, eh?

[kmay]

As far as ways to cheat the machines; a Discovery channel show Mythbusters (my favourite these days) tried every trick that had ever been suggested and none even had the slightest effect, so don't even bother :beer

[muddhunter]

I used to have a breathalyzer machine, the way to get the highest reading was to gargle a shot of 151 then blow. I held the record at .691 bac. You will get the lowest reading by gargling water before blowing, but if you haven't had a sip of booze in the last 5 minutes, the water won't help you any.

[rattle]

Originally posted by kmay
As far as ways to cheat the machines; a Discovery channel show Mythbusters (my favourite these days) tried every trick that had ever been suggested and none even had the slightest effect, so don't even bother :beer

Machines are only as good as the operator though.

[kmay]

Well, I'm sure Skid can comment directly, but my understanding is that is why these machines are used as the final say; they are not as open to operator interpretation - blow the correct volume of air, get a reading of BAC; end of story, go to jail:eek:

[rattle]

Originally posted by kmay
get a reading of BAC; end of story, go to jail:eek:

Last time I check there had to be charges laid before someone goes to jail. Well maybe until they sober up they could be held in jail.

When there are charges laid there is a lot more than the officer showing up to court and handing over the BAC ticket.

One example is there has to be RPG for a demand. It always amazed me how many times that hurdle was not even passed.