1. Dragger tubes are used to detect various other toxic gases present in the compartment
2. It works on the principle of chemical absorption of gas into chemical reagent present in the tube which changes the color of the reagent and helps in determining the ppm of the gas present
3. A sample of air is drawn into the detector tubes (opened at both ends). This tube has crystals of chemical reagent. One end of the tube is fit into the drager pump
4. Number of presses is given on the drager pump. In order to ensure that a constant air sample volume is drawn - a limiter chain is given
5. The graduation on tubes and its discoloration shows the percentage. of toxic gases present
6. Tubes are ordered as per the gas the user needs to measure. Eg of drager tubes are benzene, phosphine and hydrogen sulphide gases