Draeger Tubes used in todays workplace provide quantitative results with a high degree of accuracy, repeatability and selectivity. The printed scale allows technicians to easily view the direct reading of the concentration. Calibration by the user is not necessary. The length-of-stain discoloration does not correspond to the concentration as a direct measure but is a measure of the mass reaction of the air contaminant.
Draeger Tube use is made according to the different areas of application testing:
- Air investigation in the workplace
- Measurements in the range of the occupational exposure limits
- Technical gas analysis
- Emission concentrations
- Compressed air for breathing apparatus and compressed gases
Draeger tubes are designed for on-the-spot measurements at a particular location over a relatively short time period. Draeger Tube measurements may last from 10 seconds to 15 minutes or so depending on the particular Draeger Tube and Draeger Tube sampling pump. Some applications for short-term tubes are the evaluation of concentration fluctuations in the workplace, the measurement of contaminants in the workers’ breathing zone, the investigation of confined spaces (e. g. grain silos, chemical tanks, sewers) prior to entry and to check for gas leaks in process pipelines.
The Draeger Tube measurement system consists of a Drager-Tube and a Drager gas detector tube pump. Each Draeger-Tube contains a very sensitive reagent system that produces accurate readings when the technical characteristic of the gas detector pump precisely match the reaction of the reagent system in the tube. The Draeger Tube Pump delivers the correct volume and must also pull the sample through the Draeger Tube at the proper rate. Basically, the pump and tube form a sampling unit. To interchange the pumps and tubes of various manufacturers can lead to erroneous results.
The evaluation of the indication on the Draeger Tube is another important factor to be taken into consideration. The following are guidelines for interpreting the indication:
- continuously observe the tube during the measurement
- evaluate the indication immediately following the measurement according to
- the instructions for use
- use sufficient lighting
- a lighter background
- compare with an unused tube
Observing the tube during the measurement is particularly important to make sure that a complete discoloration of the tube has not happened without being realised. This complete discoloration can sometimes occur abruptly with high concentrations even during the course of the first stroke. A sufficient lighting source is necessary. Direct sunlight should be avoided because the UV-radiation of the sun may cause a change in the discoloration. Since such a change can sometimes occur even after a longer period of time. The reading of the tube must be done immediately following the measurement. Please download our guideline sheet for more information.
Please note: The use of other types of pumps with Draeger Tubes is not recommended. Although the volume may be the same, the difference in the flow characteristics of the pump and tube can result in considerable measurement errors.