Anyone who has seen the electric heating tube knows that the end of the electric heating tube is sealed with some sealing material. You must have a question: why the end of the electric heating tube is sealed? What is the role of the sealing material of the electric heating tube?
Through the structure of the electric heating tube, we can know that it is densely filled with MgO powder. The MgO powder has good thermal conductivity and insulation properties in a dry and dense condition. However, they all have different degrees of hygroscopicity. The MgO powder exposed at both ends of the heating tube will be greatly reduced in electrical insulation once they are wetted and absorbed. In particular, after the magnesium oxide powder is wetted and hydrated, it will hydration and then cake. The caking will prevent the moisture inside the magnesium oxide powder from being discharged. When the electric heating tube is energized, the insulation cannot be restored. Even the water in the pipe is heated and vaporized expansion, which causing the tube wall to burst.
Therefore, the function of the sealing material of the electric heating pipe is to prevent moisture molecules in the air from entering the heating pipe, the electric heating pipe needs a sealing material to seal the ends.