Breathalyzer Draeger 9250

The Draeger 9250 is the current breathalyzer test used in Connecticut. On this page, you can learn more about what the breathalyzer test is, how the Draeger 9250 works, the science behind breath testing, and how to defend yourself against breath test results. For further help with a DUI defense, contact us.


The Draeger 9250 is the breath testing machine used by law enforcement in Connecticut. It tests for the presence of alcohol when they have arrested a person for DUI. Connecticut started using this test a few years ago. It is similar to the previous breath testing machine used in Connecticut, the Intoxilyzer 5000. But, the Breathalyzer Draeger 9250 differs from the Intoxilyzer 5000 in substantial and noteworthy ways.

Breathalyzer Tests

All molecules are constantly vibrating. These vibrations change when the molecules absorb infrared light. The changes in vibration include the bending and stretching of various bonds. Each type of bond within a molecule absorbs infrared light at different wavelengths.

So, in order to identify ethanol in a sample, one must look at the wavelengths of the bonds in ethanol. They have to then measure the absorption of infrared light. The absorption wavelengths help to identify the substance as ethanol. The amount of infrared absorption tells you how much ethanol is present.

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The Draeger 9250

Much like the Intoxilyzer, the Breathalyzer Draeger has a mouthpiece with a spit trap. The mouthpiece attaches to a breath tube kept coiled around a heating unit. Also, a breath temperature thermometer connects to the breath tube. This increases the accuracy of the test.

There are two tubes – one inner tube and one outer one. The inner tube is kink proof. When you breathe into the breath tube, differential pressure sensors will measure the flow of air into the breath machine. These sensors will determine if the sample of breath given is enough to generate valid results. This ensures accuracy when the test gets preformed.

In addition, the pressure sensors save information about the air exhaled into the machine. This is so that the results can be printed and viewed at any time. The infrared source for this device is also theoretically more advanced than that of the Intoxilyzer 5000. The filament used in the Intoxilyzer degrades over time. The one in the Draeger can stand up to time better.

But, eventually it will still degrade. Infrared bounces through a sample chamber coated in polished platinum. It bounces through the chamber seven times to give an accurate reading. But, the chamber and the mirrors within the chamber are removable. This means that minor changes can happen to the path of the light beam. This can impact the results, so it is crucial to the accuracy of the test that the machine is calibrated before the test is preformed.


Unlike the Intoxilyzer, the Draeger only uses one filter. The Breathalyzer Draeger uses a single 9.5 micro filter. This single filter is supposedly more specifically geared for ethanol as opposed to the filters used for methanol and isoproprynol in the Intoxilyzer. But, other alcohols will absorb the 9.5 light and there are no filters to subtract non-ethanol substances. This is one problem with the Breathalyzer Draeger 9250. No baseline for ethanol can be established with one 9.5 micro filter.

Infrared Testing

In order to convert the infrared sample to the BAC level, the device uses an amplifier with a computer chip. Some types of Draeger models use a second system of analysis. This ensures that the results remain accurate. Once the infrared testing finishes, 1cc of the air in the chamber goes to an EC chamber for analysis.

However, the Draeger cannot verify the taking of exactly 1cc. This is a problem because exactly 1cc is needed for an accurate reading. So, the results of the test can be misleading or inaccurate. The Connecticut machine could read the amount in the EC sample. Instead, the result merely says “pass.”

The breathalyzer does not use a RFI detector because the machine should be fully shielded. This is due to the fact that it is low electric and has no moving parts. Because the device has low heat, it can be fully enclosed with no fear of it melting down.

The device is also tamper proof. This is because there is a color-coded key. Technicians have a color-coded key and password. High-level technicians will have access to all or most of the internal workings of the device and its software. Lower level employees will have limited access.

Boyle’s Law is no longer applicable for dry bath calibrations. This is because barometric compensation is built in. However, Henry’s Law still has use for wet bath simulators.

Henry’s Law

The breathalyzer has basis on the principle known as Henry’s Law. This relates to blood in a closed containerthat contains alcohol. The alcohol will evaporate until the concentration in the air above the liquid is equal to that in the liquid, also known as a fixed constant or Henry’s Constant. The ratio given to that of the blood in the human body to be used in accordance with Henry’s Law is 2100:1.

One can explain this as, “the concentration of alcohol in a normal person’s blood is said to be approximately 2100 times as great as the concentration in the air in equilibrium with it. This means that if the alcohol concentration found in blood that is in equilibrium with the alcohol in air, the alcohol concentration in the blood should be close to 2100 times greater.”

Another problem exists by this normal ratio because not every person has the same body weight, frame, and physical makeup, therefore there cannot be a norm for their blood/air equilibrium. The ratio would be much wider depending on the person being tested because the human body is not an ideal subject for a sealed container. Because of this problem with the normal ratio determined by forensic scientists, there can be up to a 0.03% error or more with a breath machine due to the normal ratio being used as a constant with the breath machine.


In addition to the issues of the ratio of the breath machine, the temperature of the individual supplying the sample can impact the reported results. Rarely does the defendant’s temperature get taken at the time the sample happens, but it could severely alter the results of the test! A temperature increase of only 2°F will cause approximately a 10% increase in BAC due to the volatility of alcohol. A drop in temperature can cause similar results. A heavy dose of aspirin can cause body temperature to reduce and thus potentially alter results. A breath machine that corrects a test result based on temperature exists, however Connecticut doesn’t use that machine.


These two issues of breath exist as a viable defense when charged with a DUI. If you took any medication or experienced an illness, you should tell the officer when they question you, or to tell your attorney afterwards. Also, if you have any medical conditions that could affect your normal blood ratio, you should let your attorney know so that they may obtain the correct medical documentation to support your claims. If you are a diabetic, the officer and your attorney should know because a diabetic can naturally produce ketones, which can skew the results of the breath test. A dedicated DUI attorney can review your medical history and investigate any possible medical defenses to the charges brought against you.

The breathalyzer isn’t used anymore. The hand held breath testing machines aren’t valid. Recently, Connecticut has passed laws to put breath machines in a system within a person’s vehicle, known as the ignition interlock program, part of Public Act 03-265.

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