Q: What are the essential structural and principle differences between single-head heating tubes and common double-head lead-out electric heating tubes?
A: A single-head heating tube, also called a single-end electric heating tube, is characterized by having all wiring terminals concentrated at one end. A spiral electric heating alloy wire is arranged inside the metal tube, the gap is filled with insulating and heat-conducting material, and the tube opening is sealed with sealing material. Unlike double-head tubes with leads at both ends, single-head tubes can be bent into L-shape, U-shape, or straight rod shape, and only one end needs to be fixed during installation, making them suitable for mold holes, small-diameter containers, and other space-limited occasions. This form was applied earlier in the mold heating field in the south, and its name comes from this.
Q: In oil heating scenarios, which parameter should operation and maintenance personnel pay most attention to?
A: Surface load. It refers to the electric power carried per unit heating area, usually in W/cm². The higher the surface load, the faster the tube wall temperature rises. If oil circulation is poor or viscosity is high, an excessively high surface load will cause the local tube wall temperature to exceed the oil carbonization point, leading to coking and carbon deposition, thereby reducing heat transfer efficiency and shortening the service life of the medium. Therefore, when selecting a model, a reasonable surface load specification should be chosen based on oil characteristics, flow rate, and volume. A lower surface load can effectively prevent oil carbonization and scorching, making operation safer and more reliable.
Q: What details are easily overlooked when installing single-head heating tubes on site?
A: First, pay attention to insertion depth. The heating zone should be fully immersed in the medium to avoid exposing a dry-burning section. Second, pay attention to tube opening sealing. Oil or water vapor may penetrate along the lead end, so it is necessary to confirm that the sealing material matches the working temperature. Third, the wiring end should be kept dry and tight to avoid local overheating caused by excessive contact resistance. Fourth, for single-head tubes formed by bending, the bending radius should not be too small, so as not to damage the internal heating wire or insulation layer.
Q: In daily maintenance, how can one determine whether a heating tube needs to be replaced?
A: A multimeter can be used to measure the resistance between the leads. If it shows an open circuit, the internal heating wire has broken. Then use a megohmmeter to measure the insulation resistance between the lead and the tube wall. If the value is obviously low, it indicates that the insulating material may be damp or aged. In addition, observing whether the tube surface has obvious bulging, cracks, or severe carbon deposition is also a basis for determining replacement.
Q: When selecting a single-head heating tube, how should power and voltage be matched?
A: Power needs to be calculated based on medium mass, specific heat capacity, heating time, and heat loss. Voltage should be consistent with the on-site power supply, commonly 220V and 380V. At the same power, increasing voltage can reduce current, but it is necessary to ensure that the insulation level meets the requirements. It is recommended to control the surface load within a reasonable range and leave a certain power margin to cope with voltage fluctuations.
