The lead end insulation protection of limit-type single-end electric heating tubes is the core safety link of equipment operation. The interior of the heating tube is filled with high-purity magnesium oxide powder, which undertakes dual functions of high-efficiency heat conduction and electrical insulation. However, magnesium oxide powder has strong hygroscopicity. Once contaminated by external moisture, dust and corrosive pollutants, the insulation performance will drop sharply, resulting in safety hazards such as electric leakage and short circuit. Therefore, standardized protection of the lead end must be done during installation and use.
Magnesium oxide powder is a porous inorganic insulating material with excellent high-temperature resistance and thermal conductivity, which is the key guarantee for the safe operation of single-end heating tubes. But its natural defect is easy moisture absorption. In humid working environments, water vapor will penetrate into the tube body from the gap of the lead end, causing the internal magnesium oxide powder to agglomerate and damp. The damp insulating powder will lose its insulation performance, resulting in electric conduction between the internal heating wire and the outer metal tube wall, triggering equipment electric leakage, tripping and even electric shock accidents.
In industrial complex working conditions, the lead end is also easy to be polluted by oil stains, plastic residues, dust and chemical volatile pollutants. These pollutants will adhere to the lead port and penetrate into the interior with temperature changes and air circulation, destroying the purity of the internal insulating material, reducing the insulation resistance, and forming potential safety hazards of electric leakage for a long time. Especially in plastic molding and die-casting production workshops, oil mist and plastic volatile gas are dense, which have the greatest impact on the insulation performance of the lead end.
To completely solve the problem of moisture and pollution infiltration, the industry has formed a unified standard installation specification: reserve a 5mm exposed section at the lead end of the heating tube outside the mold. This reserved space can effectively isolate the high-temperature and humid environment inside the mold, avoid the lead end being immersed in high-temperature steam and pollutants for a long time, keep the lead port dry and clean, prevent external moisture and dirt from penetrating into the tube body, and fully protect the internal magnesium oxide powder insulation performance.
The 5mm reserved exposed design is a simple and effective safety protection measure, which can greatly reduce the electric leakage failure rate of limit-type single-end heating tubes. While ensuring safety, it also avoids the insulation aging caused by long-term high-temperature baking of the lead end, prolongs the service life of the lead wire, and provides reliable safety guarantee for the long-term stable operation of heating equipment.
