Draeger Gas detection Tubes aka Draeger-Tubes® are used to detect 100s of different gases. The tubes are glass vials filled with a chemical reagent that reacts to a specific chemical or family of chemicals. A calibrated 100ml sample of air is drawn through the tube with a Draeger accuro® bellows pump. If the targeted chemical(s) is present, the reagent in the tube changes color, and the length of the color change typically indicates the measured concentration. Select the appropriate Draeger-Tube® according to the chemical hazard to be tested and the required measuring range. The Draeger Tube Handbook is a good source for application and specific details related to gas measurement, air flow currents and how to correctly use the tube and pump system.