Lead the rod terminal pin diameter and the size of the electric heating tube of the power of the size of the matching value

Lead the rod terminal pin diameter and the size of the electric heating tube of the power of the size of the matching value

As the electric heating tube heating element tubular heater processing is completed, the general

 sealing material for the RTV silica gel, the temperature is about 250 ℃, so the choice of the 

rod in the work of the maximum working temperature must be ≤ 250 ℃ (RTV silicone maximum 

temperature) then how to ensure that Kind of requirements?

    Through the application examples to illustrate: the design of an electric heating tube

, specifications for the 220V4000W, the use of lead rod material for the stainless steel material

, the lead rod diameter diameter of φ2.6 × 75mm, this size selection is correct and reasonable?

 We only through the calculation to see if it is correct and reasonable.

    Solution: take φ2.6 lead rod, the length of 75 mm is equal to 0.075 meters

    ① in the lead out of the current flowing through:

    I = P / U = 4000/220 ≈ 18.18 amps

    ② calculate the length of 75 mm, diameter φ2.6 mm resistance value

    Since R = ρ.L / S = 0.7 × 0.075 / 3.142 × 1.32 ≈ 0.01 ohms

    ③ the power P produced when the rod is passed through 18.18 amps on a 75 mm lead rod

    P = I2R = 18.182 × 0.01 ≈ 3.31 watts (ie, the lead rod is 75 mm long and the resulting power

 is 3.31 watts)

    ④ at 75 mm, lead the rod φ2.6 corresponding to the tube surface load q bar

    Q rod = P / S = 3.31 / 3.142 x 0.26 x 7.5 ≈ 0.54 g / cm 2

    ⑤ The stainless steel lead rod with a diameter of φ2.6 produces a total of 3.13 watts when 

flowing through 18.18 amps and the corresponding surface load of the rod is 0.54 W / cm 2, 

depending on the temperature of the tube surface load corresponding to the surface of the tube The

 surface temperature of this stainless steel lead is about 200 ~ 220 ℃.

    Conclusion: When the diameter of the heating rod of heated heating tube is φ2.6, and the

 current flowing is 18.18 amps, the temperature of the rod is about 200 ~ 220 ℃, which is lower 

than the normal temperature of 250 ℃, So meet the design requirements. If the temperature is 

higher than the normal temperature of 250 ℃, the silica gel easily in the lead-out temperature

 gradually crack occurs, resulting in insulation and electrical properties. May also be more than

 the normal temperature caused by the carbonation of silica gel, resulting in the insulation of 

the electric tube down even due to the carbonization of silica gel lead rod and tube shell 

breakdown.

    For the above situation, if more than 250 ℃ above can be improved as follows:

    ① According to the outer diameter of the electric heating tube, such as φ ≥ 10 mm, the

 outer diameter of the lead rod can be increased or the length of the rod can be increased, 

so the change can reduce the resistance value per unit length and reduce the load on the surface

 of the rod, Although the current is still flowing through 18.18 amps, but the temperature of the

 lead surface will drop to the temperature at which silicone can withstand even lower temperatures

.

    ② If the diameter such as φ ≤ 10 mm, it is still 18.18 amps current, may be appropriate to 

lengthen or replace the lead out of the material, such as pure nickel lead rod and so on. It 

should be noted that although the resistivity of the iron rod is lower than that of the stainless 

steel, it is not recommended because the surface of the rod is easy to oxidize, the strength is

 small and the contact resistance is not good.

Add: No. 16, Road 3, Sanjiang Industry Zone, Shengzhou, Zhejiang, China

Contact:Boris Yue      

Email: boris@benoelectric.com

Contact:Charles Yu     

Email: charles@benoelectric.com

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