How Do Breath Alcohol Testing Devices Work?

How Do Breath Alcohol Testing Devices Work?

Breath alcohol testing devices – often referred to by one brand name, “Breathalyzer” ­– are used by policing agencies as well as companies that have drug and alcohol policies in place. Their use is almost always done in accordance with an established alcohol and drug-free workplace policy and implemented by a drug and alcohol testing service.

These “breathalyzers” operate according to the biological response to alcohol consumption: When a person consumes alcohol, it is absorbed by the body and enters the bloodstream. As the blood passes through the lungs, trace amounts of alcohol are left behind and mix with the air in the lungs.

The testing devices have a disposable mouthpiece that the test subject blows into, filling a chamber with a sample of their breath. The breath sample is then analyzed for any detectable alcohol content. This level is represented numerically, such as .080 BAC (which is the point at which a motorist can be considered under the influence and in violation of the law). BAC is an acronym that means Blood Alcohol Content or Blood Alcohol Concentration.

The breath alcohol test is usually performed twice. The lower of the two readings is then considered the accurate reading when test results are documented for possible evidence in litigation or court proceedings (as in the case of law enforcement testing drivers under the influence).

There are three main types of devices that are used: The Breathalyzer, the Intoxilyzer, and the Alco-Sensor. Each device uses a different technology to detect the evidence of recent alcohol consumption and possible intoxication.

The Breathalyzer unit has two vials in it that each contains a mixture of water, sulfuric acid, silver nitrate and potassium dichromate. When the test subject’s breath sample is mixed with the chemicals in one of the vials, it reacts to the alcohol in the breath sample and changes color. The color change in the reacted vial is then compared to the color of the unreacted vial by a photocell system within the device. The difference in the color change that is detected by the photocell system creates an electrical current that causes the needle of the device’s meter to move. There is a knob on the device that the operator then turns to move the needle backs to its starting point. The more alcohol content in the breath alcohol test sample, the more the knob must be turned to return the needle to the starting point. The level of alcohol is then read from the knob.

The Intoxilyzer uses infrared light; the ethanol alcohol molecule absorbs a specific wavelength of infrared light. This light is passed through the test sample inside the device. The light then hits a filter wheel that is specific for these wavelengths. The light passing through the filter is then detected by a photocell and converted into an electrical pulse. A microprocessor then interprets the pulses and determines the amount of light that was absorbed. This information is then calculated to determine the BAC level of the test subject.

The Alco-Sensor uses fuel-cell technology. The fuel cell inside the device has two platinum electrodes with an acid-electrolyte material between them. The alcohol in the test sample is oxidized by the first platinum electrode and creates an electrical current that passes through a wire to the second electrode. The more alcohol in the test sample, the greater the electrical current produced. An electrical-current meter measures the level of the current, and this information is then calculated by a microprocessor to determine the BAC level of the test subject.

The use of alcohol testing devices can save employers money in lost productivity, injuries, damage to property, and other effects of poor judgment made under the influence of alcohol. They can also act as a deterrent and a means to identify employees who are in need of addiction treatment.

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