General Knowledge of Electric Heating Tubes

1. Metal Tubular Heating Element

It takes a metal tube as the outer shell and alloy heating wire as the heating body. Lead rods/wires are fitted at one or both ends. Magnesium oxide insulating medium is filled inside the metal tube to fix the heating body.

2. Lead Rod

A conductive metal part connected to the heating body, used for connecting the element to power supplies or other elements.

3. Overall Length (L), mm

The total length of straight and bent sections of the metal tube shown on the element drawing.

4. Heating Length (t), mm

The length of the section where the heating body is arranged on the element drawing.

5. Heating Surface Area, cm²

The surface area of the metal tube over the heating length.

6. Surface Load, W/cm²

Power per unit area on the heating surface.

7. Full Heating Condition

Operating conditions that enable the element to reach its specified working state.

8. Rated Voltage, V

The voltage specified in design and marked on the element shell for connection.

9. Rated Power, kW

The input power of the element specified in design and marked on the element shell.

10. Operating Voltage, V

For a single element connected to power supply, it refers to the designed working voltage (equal to rated voltage for single-end heating tubes). For a group of elements connected in series, it means the total voltage designed for the whole group.

11. Operating Temperature, ℃

The average temperature of the element's heating surface under rated power and full heating conditions.

12. Maximum Temperature

The temperature at the hottest point within the heating length when the element operates at 1.27 times the rated power under full heating conditions.

13. Simulated Operating Condition

Conditions set in accordance with relevant standards to keep the element's operating temperature basically consistent with the specified value.

14. Permissible Repair

Repair work for damaged lead rods, damaged surface coating, failed insulators or seals. The repaired element shall maintain original performance and normal serviceability.

15. Recovery

When the electrical insulation of the element drops below the standard due to service or long-term storage, restore its insulation performance to standard values by oven drying or other methods, without impairing its performance and use.

16. Damage

a. Withstand voltage below standard, leakage current over 5 mA or insulation resistance below 1 MΩ, and unrecoverable;

b. Outer shell with spark emission, molten substance, severe surface corrosion or other damages not allowed for repair;

c. Actual power of the element deviates from the rated power by more than 20%.