Which of the following is the chamber path length for the Intox EC/IR II?

Which of the following is the chamber path length for the Intox EC/IR II?

• A. 3 inches
• B. 5 inches
• C. 4 inches
• D. 6 inches

Answer: (B)

The main idea is that the chamber path length is a fixed dimension the device uses to relate infrared absorption to alcohol concentration. For the Intox EC/IR II, the distance the IR beam travels through the breath sample in the analysis chamber is five inches. This fixed path length is built into the instrument’s design and calibration, so the absorbance readings map consistently to blood alcohol concentration using that exact length. If the path were different, the amount of light absorbed at the same concentration would change, requiring a different calibration and producing inconsistent results. Therefore five inches is the correct chamber path length.

The main idea is that the chamber path length is a fixed dimension the device uses to relate infrared absorption to alcohol concentration. For the Intox EC/IR II, the distance the IR beam travels through the breath sample in the analysis chamber is five inches. This fixed path length is built into the instrument’s design and calibration, so the absorbance readings map consistently to blood alcohol concentration using that exact length. If the path were different, the amount of light absorbed at the same concentration would change, requiring a different calibration and producing inconsistent results. Therefore five inches is the correct chamber path length.