What is a colorimetric gas detector tube
It is a closed tube made of glass and containing a chemical substance which reacts (by color change) in presence of the target gas or vapor to monitor. The gratuations, commonly in ppm (parts per million) or in %/vol. (percentage by volume) offer very accurate measures with a relative immunity to interfering substances.
Field of application of the gas detector tubes
Due to the huge number of gases present in the atmosphere or resulting from a chemical reaction, it is not possible to detect them all with a gas detector.
With an amazing range of gases (hundreds), colorimetric gas detector tube can be a particularly appropriate and relevant solution in many situations. As easy to use as a breathanalyzer, they are also cost-effective – a few dozen euros for a pack of 10 tubes.
The different categories of gas detector tubes:
There are maily two categories of gas detector tubes : colorimetric tubes and dosimeter tubes (also known as dosi-tubes). There is also colorimetric plates but they are much less used and more complicated to use.
- The colorimetric tubes :
These units are by far the most known and the most used because of the large number of toxic or asphixiating gases they can monitor. To date, almost 500 references are available for use in various activity fields. Colorimetric gas detector tubes are instant measurement systems and need to be used with a sampling pump. This is a one-shot gas concentration measurement available in only a few seconds.
- The dosimetric tubes :
This is a TWA measuring system (Time Weighted Average) which measures the gas concentration on a fixed period (8 hours for example, which recpresents a working day). No pump is needed for this kind of gas detector tubes, the gas concentration is directly read on the tube after the exposure. This is an ideal and cost-effective solution to measure gas exposure in work environments : exhaust gases, formaldehyde, paint workshops…
Watch the video introducing the colorimetric and dosimeter gas detector tubes :