Dräger diffusion tubes - Time weighted average exposure TWA measurement
Dräger diffusion tubes are a simple and economical solution for determining the time weighted average concentration of toxic gases and vapors in ambient air. They incorporate the time weighted average gas concentration during the entire sampling period, which can vary from 1 to 8 hours.
These discreet and light dosimeter reagent tubes (also called dosi-tubes or badges) are attached to clothing (shirt collar, pocket, work clothes, etc.) by a plastic clip during the entire sampling period. Detailed description
Dräger diffusion tubes, dosimeter tubes
Passive reagent tubes - also called dosimeter tubes - are intended for controlling and monitoring the total daily concentrations of gas present in the air. Dräger passive tubes measure the total amount of gas breathed in during the working day (usually 8 hours). It is a simple and economical way to control the TWA (time weighted average value).
This measurement system is said to be “passive” and is based on the diffusion of contaminant molecules in the air, it does not require a pump unlike conventional colorimetric reagent tubes.
Dräger diffusion tubes measuring principle
According to Fick's first law, the contaminant molecules move by themselves inside the tube or the badge. The driving force behind this molecular flux is the difference in concentration between ambient air loaded with harmful substances and the inside of the tube. As Dräger diffusion tubes do not require a pump, they are particularly suitable for individual monitoring measurements.
The graduated scale printed on the tube represents the product of the concentration and the exposure time (for example ppm x h). To establish the average contaminant concentration, divide the scale reading by the exposure time (or sampling time).
It is a simple and economical method of measuring the time weighted average exposure value (TWAEV), requiring no special technical skill, no analysis costs in a specialized laboratory, nor waiting time.
- Dräger reagent tubes for spot gas measurementsStarting at $89.95
- Dräger simultaneous test kits - Semi-quantitative gas measurementStarting at $100.04
- Accuro manual pump for Dräger reagent tubesStarting at $690.70
- X-act 5000 automatic pump for Dräger reagent tubesStarting at $1,382.34