1. First of all, it may be because the electric heating tube itself has been burnt, so the surface will appear black. If this is the case, everyone should pay attention, this product should not continue to use.
2. It may be caused by abnormal power supply or frequent power failure. The electric heating tube in use may repeatedly appear black because of power failure or abnormal power supply.
3. It may be caused by poor contact of the controller contact point and poor contact between the power cord plug and the electric hot socket.
4, the oxidation phenomenon caused by electric heating, electric heating tube after heating for a period of time, due to the influence of air or humid environment, the surface will produce some black objects due to oxidation, just like burning a stainless steel with a candle flame, A black substance is produced on the surface. This situation is more common, and the black oxide is non-toxic and the electric heating tube can continue to be used.
Therefore, when the electric heating tube is heated for a period of time, the surface appears blackening, we have to judge what causes it. If it still has a resistance value, it can work, indicating that it is only caused by oxidation; if there is no resistance value, it should be burned out.