Using the principles of gas diffusion and colorimetric reaction, Dräger Color Diffusion Tubes allow the user to reliably measure time-weighted average (TWA) concentrations for up to eight hours. An easy-to-use tube holder allows safe tube end removal and secure sampling. Color Diffusion Tubes can be evaluated at any point during a work shift. The calibrated scale printed directly on each tube indicates parts-per-million-hours (ppm-hours). For a TWA reading, simply determine the point where the stain length ends and divide this reading by the total length of sampling time. No pumps, charts, or analyses are needed.
To use a Diffusion Tube, place the tube in the tube holder with the red dot on the tube visible above the hinged portion of the holder
(Figure 1) . | 
Figure 1 |
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| Open the tube by grasping the ends of the tube holder, with the red dot on the tube away from the body, and bending the holder until the tube breaks (Figure 2). | 
Figure 2 |
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| Remove the end of the tube from the holder and discard. The Diffusion Tube is ready for use. Snap the tube into the tube holder with the open end positioned at the open end of the holder (Figure 3). | 
Figure 3 |
Attach the diffusion tube holder to a worker's pocket or lapel and note the starting time of the test. At the end of the work shift, or any time during the workshift, the user can evaluate the tube.
