Heating Element Design Factors

Heating elements are non-standard products, and the structure is also various. There are many factors that affect the heating function, such as material, voltage, power, and component size. The design of the structure is often convenient for the installation or aesthetics of the heating equipment. Therefore, there are many things to be aware of when designing the heating element structure. The following are some rules for the design of the heating element structure for reference when selecting the customer.

  • 1. The heating element should be designed to take into account the effects of thermal expansion and contraction, ablation, oxidation, creep, etc., so as to avoid failure due to deformation during normal operation.
  • 2. The internal structure of the heating element shall be designed to ensure that the highest temperature of the material selected for the heating element or the highest temperature that may be encountered during processing is not damaged and still operate reliably. 
  • 3. The welding structure design of the heating element should conform to the delivery standard. The weld of the pressurized heating pipe, especially the part inside the container, should be as small as possible, and the setting of the weld should be easy to check.
  • 4. The design of the heating element housing and its accessories subject to pressure must conform to the standards of delivery.
  • 5. The heating element (including the end) must be sealed.
  • 6. Heating elements used for the heating of aggressive media must use corrosion-resistant metal tubes or protective sleeves to ensure the working life of the heating elements.
  • 7. When the heating element shell is ordinary steel or other alloy material with better performance than ordinary steel, the wall thickness should be not less than 0.35mm. When the outer shell is made of copper or copper alloy, it must be based on the corresponding mechanical strength. Adapt to the harsh working environment.
  • 8. The bending radius of the heating element should not be less than 2.5 times the diameter of the heating element.
  • 9. The curved shape of the heating element must ensure that the inner end of the extraction rod is on the straight part of the element and the distance from the starting point of the bending should be not less than 10 mm.
  • 10. The gap between the two intercepting portions of the heating element with a potential difference greater than 40V and the gap between the intercepting portion and the outer casing and the thickness of the insulating filler shall be not less than 1 mm, and the distance between the exposed lead wire and the outer casing shall be not less than 1 mm. (Note: If there is an agreement, the above clearance and distance can be less than 1mm, but the design needs to be strengthened and carefully manufactured to ensure performance and reliability)
  • 11. The cross-sectional area of ​​the heating element lead-out wire should not be less than 7 times the cross-sectional area of ​​the heating wire.

The heating element has no special requirements for the temperature of the working environment, but the humidity of the air in the environment cannot be greater than 95%, and there is no flammable, explosive or corrosive gas. The external working voltage of the heating element should not exceed 1.1 times of the rated voltage. Before the heating element is operated, it must be ensured that the housing is effectively grounded to avoid electrical accidents.

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