Alcohol Detector

Have you ever gone out with friends and had a few drinks, then wondered if you were over the limit? This is when an alcohol detector could come in handy.

There are a number of alcohol detectors on the market. The name “Breathalyzer” has become synonymous with alcohol testing, but this is not the only brand. An internet search for “alcohol detectors” will turn up a number of brands. Police use them to estimate blood alcohol concentration (BAC), although this is more accurately determined through a blood test.

This article highlights three popular types: the Breathalyzer, the Intoxilyzer and the Alcosensor III or IV. Each type of detector has a mouthpiece for the user to blow into, and the chamber to hold the breath. Other parts of the device may vary.

The Breathalyzer

The first and probably best-known is the Breathalyzer. The three parts are the mouthpiece, two glass vials for the chemical reaction mixtures and photocells which measure the color change associated with the reaction of the dichromate and alcohol.

In this machine, a suspect’s breath is bubbled through one chamber of sulfuric acid, potassium dichromate, silver nitrate and water. The reacted mixture is compared to the unreacted mixture, causing a needle in the meter to move, which the operator must return to its resting place by a knob on the machine. The level of alcohol is determined by how much the operator must move the knob to return the needle to rest.

The Intoxilyzer

The Intoxilyzer is a device that uses infrared (IR) spectroscopy, which identifies particles by their absorption of infrared light. The bending and change of wavelengths and infrared absorption in ethanol are measured to determine the amount of alcohol in a person’s system.

The Alcosensor

The Alcosensor III or IV uses a fuel cell with two platinum electrodes with an acid-electrolyte material between the electrodes. From the first electrode, electrons in the alcohol molecules flow through a wire to a meter which measures the electrical current and to the other platinum electrode. After protons are oxidized, a microprocessor measures the electrical current to calculate BAC.

It is against the law to drive while intoxicated, in all 50 states and the District of Columbia, the legal BAC limit is .08 percent. These detectors are helpful tools for screening.