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Breathalyzer Selection Guide- How To Select a Breathalyzer
Thursday 07 November, 2013.
The purpose of this guide is to provide you with an overview of breathalyzers for sale in just a few minutes so that you can make an informed decision about which alcohol breathalyzer is right for your particular application. We try to summarizes how alcohol testers work and the most important factors to consider when selecting one. We also provides an overview of the four types of alcohol testers available today.
How Does An Alcohol Tester Work?
Alcohol affects us when we absorb it into our blood stream. As a result, it is possible to determine our degree of intoxication by ascertaining the alcohol percentage in the our blood -- known as "blood alcohol concentration" ("BAC"). An individual's BAC can be measured in two ways: (1) invasively (drawing a blood sample), and (2) non-invasively (breath, saliva, or urine samples). Invasive testing is generally performed at health care facilities by specialists equipped to perform the procedure, while non-invasive testing is used primarily by law enforcement officials because it is more feasible to conduct a test in the field. Of the different types of non-invasive testings, breath testing is the most common procedure because it is quick and inexpensive.
Many people wonder how breath alcohol content (“BrAC”) is converted into BAC. To understand this process requires a quick review of how our respiratory system works. Basically, as air moves in and out through the same set of tubes, continuous mixing of inhaled and exhaled air occurs. Air moves from the nose/mouth to the trachea to two tubes (one for each lung), known as the bronchi. The bronchi separate into several subdivisions, which end in a large number of tubules. At the end of the tubules are the alveoli, and a person's lung contains million of alveoli. Surrounding the alveoli is a fine network of capillary blood vessels. It is at this level where the blood exchanges chemicals with the air in the lungs. Studies show that the alcohol concentration in the lower portion of the lungs is proportionate to the concentration of alcohol in the blood at a ratio of 2100:1.
Correlation Between Blood and Breath Alcohol
To obtain an accurate correlation between blood and breath alcohol levels (typically 2100:1), the breathalyzer test must be able to capture an air sample from the lower portion of the lungs. A person's vital capacity (volume of air that can be expelled without collapsing the lung) can range from 1 liter to 7 liters, depending on factors such as age, gender, physical condition, and disease status. If a breath alcohol analyzer requires too long of a breath sample before testing the person's breath alcohol content, then the risk is that the person will not be able to provide a sufficient breath sample. On the other hand, if the alcohol tester captures a person's breath alcohol content only after the person exhales a minimum amount of air, then the correlation between breath alcohol content and BAC will be poor. Typically, alcohol tester protocols will require the test subject to exhale air for 4 - 8 seconds to obtain a high correlation between breath alcohol content and BAC.
Some the newer and more advanced alcohol testers will track the force of the exhale over time to ensure an adequate lung volume is achieved. Most professional-grade alcohol testers measure the force of the breath sample to prevent “fake blowing” through the device and inaccurate results.
What factors are relevant when selecting an accurate alcohol tester?
Many factors should be considered when selecting a breathalyzer machine. First and foremost, accuracy should be an important factor unless you are merely looking to purchase a novelty item at a low cost. If you care about accuracy, then it is important to compare the accuracy levels listed in the specifications for each unit. However, keep in mind that the accuracy reported in the specifications is often mistakenly viewed as the true accuracy of the unit when testing a human subject. The accuracies listed in the product specifications for each unit are usually based on a controlled testing environment using an alcohol simulator device. This does not account for the ability of the alcohol tester to capture an accurate breath sample. As a result, you should consider the following factors to determine the "true accuracy" of an alcohol tester:
Overview of Types of Alcohol Tester Technologies
There are essentially four types of technologies used in alcohol testers to measure the air in lungs to determine an individual's estimated BAC:
Semiconductor Sensor Models
The presence of semiconductor units has increased rapidly over the past few years. The main advantage with these types of units is that they are relatively inexpensive. Since many semiconductor models are available, it is important to look at several relevant factors when selecting which unit is right for you. The Relevant Factors to Consider When Selecting an Alcohol Tester are discussed above.
Based on the various factors to consider when selecting an alcohol tester, we break down semiconductor models into three levels: Level I - Novelty Grade; Level II - Intermediate Grade and Level III - Professional Grade
Level I: Novelty Grade
Many alcohol testers in the market are designed to test passive samples of breath, which means a breath sample is taken without the use of a mouthpiece. It is common to use passive testing because it is easy to simply test for the presence of alcohol on the breath. However, passive testing is typically less accurate and can often lead to unreliable results. The results of passive testing units are greatly altered by the surrounding environment as their sensor is highly exposed to any pollutants in the air. It is can also be difficult for the user to judge the correct distance to the space where to exhale into the unit.
Level II: Intermediate Grade
Testing of Minors
Currently, a few semiconductor sensor alcohol tester models are capable of re-calibration and are designed to use a mouthpiece to improve the capture of a breath sample. However, these units are not programmed to test a deep lung air sample that represents the lung air that is proportionate with blood alcohol. We rate these units as intermediate grade units because they are more accurate than passive testing models but they do not meet DOT / NHSTA accuracy standards necessary to be professional-grade screening devices.
Level III: Professional Grade
We rate units as professional grade when they meet the strict requirements for approval by the Department of Transportation (DOT), National Highway Traffic Safety Administration (NHTSA). These units have a well designed breath capturing mechanism to sample the deep lungs breath. It is our opinion these are the best handhold alcohol screeners on the market.
The fuel cell breathalyzer is the gold standard in terms of handhold alcohol testers available today. The fuel cell units are used by police officers, employers, substance abuse counselors and the like. For the most part, the fuel cell unit is about as accurate as a professional semiconductor unit (such as the Alcohawk TM), but the fuel cell units are designed to be more specific towards alcohol detection. As a result, there is a smaller chance that the unit will provide false readings from non-alcohol substances. Some of these units are designed as evidential testers, which mean the results can potentially be used as evidence in a court of law. The only major draw back with fuel cell units is the cost, as they retail from $400 - $700 per unit. Several high quality fuel cell units are produced in America, and the units we highly recommend are the FC Series units manufactured by Life loc Technologies, Inc.
Infrared (IR) Spectroscopy and Gas Chromatography Models
These units are often found at the police station and are used mainly as evidential testers because they are extremely accurate and specific. To our knowledge, these units are not manufactured to be handhold / portable units. These units are also very expensive, usually over $1000.