Breath Test Devices – How They Work

August 08, 2014

breathanalyzerAny time a police officer suspects a motorist of DUI, that is ‘Driving Under the Influence’ of Alcohol or Drugs, he or she will stop the driver and ask them to take the breath test. A breath test device or breathalyzer will be used by the officer to ascertain the Blood Alcohol Concentration (BAC) of the motorist.

Needless to say if your BAC level goes beyond 0.08, you will be charged with DUI which results in a number of negative consequences such as the suspension of your license, possible jail time and you will also have got a criminal record for the rest of your life.

Breathalyzers are mainly used in roadside testing on suspicion of DUI because while you are out on the roads it is pretty much impossible for the police to conduct a blood test. This is why the alcohol breath test is usually referred to as the Preliminary Alcohol Screening (PAS) test. Albeit you may at first be required to take a few field sobriety tests like walking in a straight line or standing on one foot while counting, patrol officers today carry along a breath test device whose results will be the final determinant on whether or not you will be arrested for DUI and required to take further tests at the station.

Bearing in mind that the results of your breath test are crucial when facing DUI charges, it is essential that you know how breath test devices work and discover ways of turning them to your advantage whenever necessary.

How They Work

How a breath testing device works will often depend on the technology that was used to create the machine. Several technologies are used today and each results in a breathalyzer working in its own unique way. There are three main types of breath testing machines.

  • Color Changing Breathalyzers

This type of breathalyzer is made with two glass vials each of which holds a mixture containing specific chemicals. The chemicals in each of the vials usually include Silver Nitrate, Potassium Dichromate, Water and Sulfuric Acid. When a suspected motorist breathes into the device, a sample of their breath will bubble through one of the glass vials.

If the person had been drinking, introduction of the alcohol content in the vial from their exhaled breath will lead to the following chemical reactions:

  • Sulfuric acid quickly starts removing any alcohol content from the blown air or breath; into the liquid solution.
  • Alcohol chemically reacts with potassium dichromate to give out potassium sulfate, chromium sulfate, acetic acid and water.
  • Silver Nitrate will naturally catalyze the reaction so that results can be reached at fast enough.

When this reaction is over, contents in the vial where the reactions were taking place will change color from reddish-orange to green because the dichromate ion (which is reddish-orange in color) will be converted to chromium ion (which is green in color). Remember this will only happen in the presence of alcohol.

The mixture is then compared to the unchanged mixture of the second dial as a way of determining the Blood Alcohol Concentration level of the motorist.

  • Fuel Cell Devices

Fuel Cell breath test devices make use of a similar technology to the fuel-cell technology that today is used to act as a vehicle power source. Typically the device will have two platinum electrodes inside separated by a porous acid layer. As soon as the breath containing alcohol content is passed through the cell, an oxidation reaction will occur whereby the platinum electrodes will oxidize the alcohol producing a certain acid. Protons and electrons will also be produced in the process resulting in the production of electric current. The greater the alcohol content the greater the electric current produced symbolizing a higher blood alcohol concentration.

Breathalyzers that are legally relied upon in ruling court cases are always Fuel-Cell Breathalyzers. Modern ignition interlock devices have also started making use of the Fuel Cell technology.

  • Intoxilyzer Devices

Intoxilyzer devices generally rely on infrared technology to detect the level of intoxication. The technology bases on the fact that different types of molecules have different vibration speeds hence tend to absorb infrared differently. There is an internal lamp positioned inside the intoxilyzer that emits an infrared broadband beam. The beam will pass via the chamber where the breath from the motorist has been stored and thereafter pass through a filter wheel. The filter has been designed in a way that it can detect some particular wavelengths which are mainly absorbed by ethanol in the breath of a suspected driver. Blood alcohol content levels are determined by how great the light absorption is.


Tips to Alter Accuracy of Breath Test Devices

Let’s first be clear on one thing. It is not only lawfully wrong to be driving while drunk or under the influence of drugs but it is also completely unsafe for you and any other person on the roads. Some accidents that are a result of drunk driving end up being fatal and it is simply not right to risk the life of any human through drunk driving.

Nonetheless, there may be times when you are caught driving and perhaps you had drunk a few bottles. In such instances, it pays to avoid getting very high readings through the breathalyzer test because that could easily land you in huge legal trouble with many other grave consequences on your personal life.

There are two main ways you can alter the accuracy of breath test devices so that there is either an error in getting results or the device generates significantly lower BAC readings.

  • Take a Shallow Breath

The average ratio of the alcohol content on one’s breath to that of their blood is often approximately 2100:1. In simpler terms this means that one milliliter of blood will contain the same amount of alcohol to 2100 milliliters of the breath you exhale. Therefore, you really have to make a deep breath for any breathalyzer to accurately determine the alcohol content in your blood at the time of arrest.

What you’ll want to do when you are pulled over is just the opposite. Take a shallow breath or try not to breathe directly into the device. This way there will either be an error in your readings or the reading will be inaccurate and lower than it should be for that matter. In some scenarios, if you had passed the field sobriety test, the officers may even let you go.

  • 20 Minutes ‘Time Out’

Most breathalyzers will record an inaccurately high reading if you had taken alcohol within 20 minutes of taking the test. This inaccuracy is caused by the fact that there will likely be some alcohol still in your mouth at the time of taking the test. Since the alcohol in your mouth is definitely stronger than that found in the exhaled breath, the readings tend to be high and inaccurately so.

For this reason, it is recommended that you wait 20 minutes after your last alcohol drink before taking a breathalyzer test. Assuming that you want to drive and haven’t drunk much, wait for 20 minutes after your last drink to do so. By doing this, even if for some reason you are stopped by the police, you can be sure that the breathalyzer will produce accurate readings that may prove your BAC level is below the required threshold.


Buying Your Own Breathalyzer

Particularly if you often like to enjoy your drink, purchasing your own breathalyzer is something you want to consider. Having a personal breath test device will help you drink responsibly and know when you are not fit for driving, as you can always check your BAC level before going out to drive.

While you are at it, avoid buying secondhand devices which may be damaged thus could provide you with inaccurate readings. The best breathalyzers are often quite pricey because of the advanced technology used to make them but they are certainly worth the money; since they will provide you with accurate and reliable readings.

Be sure to keep in mind that breathalyzers ought to be re-calibrated after carrying out about 200-300 tests in order to cinch continuous accuracy of results.