JB/T 2379-2016 requires insulation resistance ≥1MΩ and dielectric strength 2kV/1min for industrial metal tubular electric heating elements. If selection is based only on rated voltage matching while ignoring the correspondence between surface load and medium heat transfer conditions, the local temperature of the tube body may exceed the allowable range of the material during actual operation, leading to decreased insulation performance. The GYY5-380 tubular electric heater takes medium adaptability as its core in structural design, providing selection personnel with clear parameter boundaries.
For clean water heating, 304 stainless steel or copper tubes are recommended, with surface load controlled at 6~8W/cm²; for oil and heat transfer oil scenarios, 304 or 321 stainless steel should be used, with surface load reduced to 2~4W/cm²; for corrosive liquids, 316L stainless steel or titanium alloy is required, with load around 3~5W/cm². For static air heating, finned structures should be used, with surface load around 1~3W/cm²; for flowing air, it can be relaxed to 3~6W/cm². The differences in the above values originate from the coupling relationship between the medium heat transfer coefficient and the tube wall temperature. When selecting, match the actual medium accordingly to avoid coking or shortened service life caused by excessive load.
This model has a rated voltage of 380V, and the working voltage is allowed to not exceed 1.1 times the rated value, suitable for conventional industrial three-phase power supply. Tube diameter range is φ6~φ30mm, and the shape can be straight single-end, straight double-end, U-shaped, W-shaped, spiral, finned, and special-shaped structures customized according to equipment space. The design service life generally exceeds 10,000 hours, energy conversion efficiency exceeds 95%, insulation resistance ≥1MΩ, and dielectric strength 2kV/1min. The wiring terminals should be placed outside the insulation layer to avoid contact with corrosive, explosive media and moisture.
The effective heating area of liquid heating elements must be fully immersed in liquid or solid metal, and dry burning is strictly prohibited. When water quality is hard, regularly remove scale from the tube surface to maintain the heat dissipation path. The metal shell must be reliably grounded. When heating fusible metals or solid nitrate salts, first reduce the voltage until the medium melts, then raise to the rated voltage; when heating air, arrange the elements in a cross-uniform pattern to ensure uniform airflow distribution. The above boundary conditions together with the aforementioned surface load values constitute the input items for selection calculation. Deviation from any condition requires recalculation of the power density.
