Colorimetric tubes are used to analyze a wide range of gases. This isn't new technology. Draeger made their first tubes in 1937. And while there certainly have been improvements and the range of testable gases has greatly expanded, the fundamental manner of determining chemical concentrations in the air has stayed basically the same.
Draeger tubes contain a chemical color reagent that transforms colorless chemical compounds into colored, and produce consistent results of absorption depending upon the concentration of the compounds they are subjected to. Those results can be viewed and measured by looking at the clearly delineated gradation marks on the outside of the tubes.
In fact, using Draeger tubes is often easier than describing how they work. Of course the same could be said for a whole bunch of technology - iPhones, industrial lasers, toaster ovens. Colorimetric tubes are used in a wide range of industries but they are not necessarily used by highly technical people. For the most part they are used by the people working in the field; not scientists, but site maintenance professionals and contractors. That is one of the reasons Draeger tubes have continued to be so popular. Taking periodic samples of the atmosphere in potentially dangerous areas is mandatory, but not every plant or work site wants or needs the more complicated wireless, electronic gas detection technology.
The pump used to draw air through the tubes also couldn't be simpler. The Accuro Detector Tube Pump is a manually operated bellows-style pump. Each set of Draeger tubes for gas detection comes with instructions that tells how many pumps a correct reading will take. A counter on the side of the unit makes sure you know how many times you have completed.