After long-term operation of a duct-type industrial electric heater, maintenance personnel may encounter vibration of the heating tubes caused by airflow pulsation and frequent operation of the over-temperature control device inside the junction box. Such problems are mostly related to loose support structures or dust accumulation in the duct. It is recommended to check the tightening status of the steel plate supports every quarter, clean the attachments on the surface of the heating tubes, and verify whether the set value of the over-temperature protector in the junction box matches the current working conditions. If vibration persists, temperature-resistant damping pads can be added at the support points.
For equipment used in explosion-proof locations such as chemical, petroleum, and natural gas facilities, it is necessary to focus on confirming whether the flameproof surfaces are corroded and whether the sealing rings of the cable entry devices are aged. During inspection, a torque wrench should be used to recheck the bolt tightening torque to avoid damaging explosion-proof performance due to looseness. It is strictly prohibited to open the junction box while it is energized. If damage to the flameproof surface is found, professional personnel should be contacted to evaluate and repair it; do not grind or handle it by yourself.
Temperature control deviation directly affects heating effect and safety. It is recommended to calibrate the temperature control instrument once every six months, comparing the deviation between the actual duct outlet temperature and the displayed value. If the deviation exceeds the allowable range, check whether the thermocouple installation position has shifted and whether the compensation wire connection is reliable. For the three specifications of low temperature, medium temperature, and high temperature, the calibration cycle can be appropriately adjusted according to usage frequency, but it should not exceed one year.
