Use & Limitations of Draeger tubes on Oil Tankers:
Multigas Detector or Draeger Multiple detector:
- This is used to detect the presence of a variety of toxic gases inside the compartment.
- They work on the principle of chemical absorption of the gas to be detected by a re-agent which gets discoloured.
- A sample of the atmosphere is drawn into a tube containing crystals of the reagent.
- The tube is graduated and the level of discolouration indicates the concentration of the vapour in the sample.
- The amount of air drawn through the tube must be exactly the same each time, to ensure this the bellows must be fully compressed and allowed to expand to the full limit of the limiter chain.
- The tubes have a shelf life of two years.
- Both ends of the tube are broken before use and one end is fitted into the pump head.
- Different tubes are used for detection of different gases.