Faults and Limitations of Blood-Alcohol Level Machines

The "BAC DataMaster", like several other breath-testing machines, operates using infrared analysis. Unfortunately, infrared analysis is subject to many flaws so breathalyzer tests don’t always yield accurate results.

The main flaw that infrared "breathalyzers" are subject to is specificity. The designers of the DataMaster understood this and hoped to minimize this problem by using two wavelengths. The microcomputer was integrated to control sequencing, calibration and self-checking, enabling ease of use and mitigating user error. The software also had the option to be calibrated to meet the requirements of various jurisdictions or agencies.

1. An "external alcohol simulator standard pump outlet" to test the accuracy of the machine.
2. A sample preservation system — allows the officer to insert a vial to capture and preserve a second breath sample either for double-checking or for defense testing.

Verax Systems is the designer of the BAC Verifier DataMaster which was made due to request from Washington State. They first designed the BAC Verifier for a bid, but to comply with the requirements they had to scrap that model and come out with the later design. The original is only slightly different, for instance having a plastic case impregnated with metal while the later model is made with metal. The main changes were in the design of the machine due to its shortcomings. They made a different printer to be included with the model that could print multiple copies of the evidence ticket; a different layout to make the machine easier to repair; a new central processing unit (CPU) to reduce the electrical interference noticed in the circuitry; different data collection and storage--changes in the algorithm to calculate the presence of acetone in a breath sample and in the previously defective "erasable programmable read only memory" (EPROM) used to calculate BAC; and changed breath-tube mounting.

It is interesting to note that Washington’s specifications included major deficiencies with the first Verifier. Yet the old Verifier is still used in other parts of the country.
Besides the problems with its predecessor, the Verifier, the DataMaster has had its own quandaries in meeting specifications. The first eight machines that were used failed to meet Washington State’s specifications and had to be returned. Twenty-five more machines had to be repaired because of critical failures that resulted in bogus readings. Some had meter valve instability, while others were thrown off by their own infrared lamp.

Not only have they encountered these numerous errors over the years there are also very temperature sensitive parts in both the Verifier and DataMaster. In the field, officers are supposed to follow guidelines that direct the operator on how to avoid mistakes due to temperature.

1. For any given breath machine, the simulator solution has to be kept at 34 degrees centigrade, plus or minus .02 otherwise it will give inaccurate results. For example a decrease of one degree will cause a 6.8 percent decrease in the amount of alcohol, yielding a falsely higher BAC reading for tested breath samples. The human factor further renders the results unreliable since an operator is supposed to check the thermometer attached to the simulator.
2. The sample chamber has to be heated to exactly 50 degrees; this is supposedly monitored by the machine's computer.
3. The detector has to be cooled to near freezing; this is also theoretically monitored by the computer.
4. If the breath tube is not properly heated to 50 degrees, condensation can form in the tube, capturing alcohol during a test. So it’s possible that alcohol residue will show up in later breath samples from a previous suspect’s test. Even though the breath tube must be at a 50 degree temperature in order to give accurate readings, the Operator's Manual tells the operator only to "check that the mouth piece is warm to the touch."
   

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