San Antonio Injury Attorney Blog
In our last blog entry, we began our discussion of the scientific formulas behind a DWI breath test on the Intoxilyzer 5000 . The machine’s objective is to measure the amount of alcohol in the driver’s breath. It is critical for a New Braunfels criminal defense attorney to highlight the weaknesses.
The underlying weakness of the machine is that it supposed to calculate whether there are 0.080 grams of higher of alcohol per 210 liters of breath. Yet the machine does not examine or even hold 210 liters of air. An oil drum containing over 50 gallons holds 210 liters of air. A person’s lung holds about 6 liters of air. In reality the Intoxylizer 5000 only holds eighty (80) or so MILLILITERS of air, the equivalent of a soda can.
A gram of alcohol is comparable to an Equal packet. In reality, the Intoxilyzer is attempting to measure eight (8) one-thousandth of that size. If the formula is 0.080g/210L and the Intoxilyzer can only hold eighty (80) milliliters, then that is the equivalent of .00003 grams of alcohol to be proportionate to 210 liters.
What does this mean ultimately ? It means the Intoxilyzer has to detect an incredibly minute amount of alcohol in a breath sample reliably.
To work properly, the driver must exhale 81 milliliter of air into the machine. An infrared light analyzes the molecules in the breath in conjunction with photoelectric cells and a light filter. The photoelectric cell examines the alcohol molecules and measures the amount of alcohol as if the full 210 liters of air were in the chamber. The machine spews out a Test Record.
The printout Test record lists the alcohol concentration with an empty air chamber which should be 0.000 under the heading of Alcohol Concentration. The driver then gives the first of two samples of air by blowing into the Intoxilyzer chamber. After testing the sample, the chamber is flushed with air from the room – there is no filter on the chamber when the air is flushed in. Before the 2nd sample is measured, a test sample is pushed through the chamber for measurement. The test sample is supposed to have 0.080 grams of alcohol in the water. The technical supervisor formulates the test sample. Another sample of air from the room is pushed through the chamber.
The 2nd sample is taken and the chamber is flushed out with room air again. With 2 samples, the jury is instructed to only account for the lower sample. In our next blog entry, we will discuss how a San Marcos DWI attorney can exploit accuracy issues with the Intoxylizer 5000.