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| Module 1: Occupational Hygiene - Section 5: Instrumentation |
| OH5.2: Instrumentation - Detector Tubes |
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| Module 1: Occupational Hygiene - Section 5: Instrumentation |
| OH5.2: Instrumentation - Detector Tubes |
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One of the simplest methods available for monitoring gases and vapours is use of detector tubes. A detector tube is a glass tube that contains solid chemical reagents and which is sealed on both ends. The ends of the tube are broken to expose the reagent to the contaminant of interest. A colour change indicates presence of the chemical contaminant. The degree of colour change or the length of stain gives a measurement of the concentration of the particular contaminant in the air.
Detector tube sampling can involve either short- or long-term periods. Short-term samples are taken over seconds or minutes, usually using a hand-operated pump to move air through the tube. Long-term samples are taken over periods of hours using battery or electrically operated pumps with an attached flow meter. For an improved level of accuracy air moving devices should be checked for leaks and calibrated frequently.
Indicator tubes are relatively inexpensive, easy to use and can measure a variety of airborne contaminants. Although detector tubes can provide valuable information in workplace assessment, there are limitations associated with their use. These include:
