Which detection tool provides pass/fail indications but is not continuous?

Which detection tool provides pass/fail indications but is not continuous?

• A. PIDs detect volatile organic compounds but may miss inorganic gases and require calibration
• B. Infrared detectors identify certain chemical signatures but limited by line-of-sight and interference
• C. Colorimetric tubes provide pass/fail indications but are not continuous
• D. Multi-gas meters measure several gases at once but may not identify unknowns

Answer: (C)

Colorimetric tubes give a simple pass/fail result for a specific contaminant at a defined concentration. You pull a known volume of air through the tube, and if the gas is present above the tube’s calibrated threshold, the reagent changes color along the tube. You then compare that color change to a scale to decide pass or fail. This is not continuous monitoring because it provides a single, discrete result for one gas at one threshold, not ongoing, real-time readings. To test again or for another gas, you need a new tube and a new sample, so there’s no continuous data stream. This makes them ideal for quick screening to see if a concentration exceeds a limit, rather than providing a continuous measurement or identifying unknowns.

Colorimetric tubes give a simple pass/fail result for a specific contaminant at a defined concentration. You pull a known volume of air through the tube, and if the gas is present above the tube’s calibrated threshold, the reagent changes color along the tube. You then compare that color change to a scale to decide pass or fail. This is not continuous monitoring because it provides a single, discrete result for one gas at one threshold, not ongoing, real-time readings. To test again or for another gas, you need a new tube and a new sample, so there’s no continuous data stream. This makes them ideal for quick screening to see if a concentration exceeds a limit, rather than providing a continuous measurement or identifying unknowns.