How does the intoximeter work?

Intoximeter EC/IR

The police in England and Wales currently use a machine called the EC/IR Intoximeter.  You may hear other names such as intoxilyzer or alcohometer banded about, these are all names of different machines that can be used to test the alcohol content of somebodies breath.  They are model names used by different manufactures.

The intoximeter is the one most commonly used at the time of writing across England and Wales.  It is a very sophisticated machine that works by looking at the alcohol content in the air expelled from the lungs.  As you breath out, the alcohol content will gradually rise until you reach the air from the deepest part of the lungs.  At that point, the level of alcohol will plateau.  Once the intoximeter detects this happening it will divert a tiny amount of breath into a fuel chamber where it will conduct the final alcohol determination, which is the reading the machine produces at the end.

As well as this, the intoximeter constantly monitors the flow of air being passed into it.  This is done to prevent any attempt to cheat the test.  This means that if you stop or reduce the force of your blow into the intoximeter the machine will detect the change and end the attempt resulting in a "fail".

Because the intoximeter can detect deep lung air, the machine can easily be used by anybody regardless of their lung capacity.  Because breath alcohol can form a mini-plateau at the start of a blow, the machine will not take a reading in the first 3 seconds of a blow, although it can do so at any time thereafter when it detects the main plateau of alcohol in your breath.  Thus somebody with a small lung capacity is likely to be expected to blow for a much shorter time than somebody with a large lung capacity.

These safeguards are not present in the roadside breath test machines used by the police prior to arrest and can often explain why somebody was able to provide at the roadside but not at the police station.

The safeguards can also make it difficult for some people to successfully provide a specimen at the police station, especially when officers instruct you to blow like you did at the roadside!

If you have been accused of drink driving or failing to provide a specimen of breath for analysis and would like expert legal advice from a solicitor who understands how the law and breath test procedures work in detail then contact us now on 020 8242 4440 and ask to speak with Nick Diable.