Facing many suppliers, many people hope to buy cost-effective electric heating tubes. How to judge the quality of the electric heating tube provided by the supplier? There are generally the following standards:
1. Is the design reasonable?
This includes the selection of the power of the heating tube and the material of the outer tube. The power design of electric heating is a comprehensive consideration of various factors, mainly calculated according to the surface load of the electric heating tube, and the requirements for the surface load of the electric heating tube for liquid heating and air dry heating are also different.
Generally speaking, when the scale is not serious, the surface load of the electric heating tube should be controlled below 10W/c㎡;
The surface load of the heating tube for air dry burning is controlled below 8W/c㎡.
Of course, the final power design needs to be designed according to the specific situation. The above-mentioned is a very conservative design. Please contact us directly if accurate calculations are required.
For the selection of the outer tube material of the electric heating tube,
SUS 304 is used for heating in non-acid and non-alkaline liquids or when the air is dry, the working temperature is below 300℃;
Weak acid and weak alkaline liquids are made of SUS 316L;
SUS 316L+ coating for strong acid and alkali;
The working temperature of SUS 321 is between 300℃-500℃ when it is used for air dry burning;
The working temperature of SUS 310S is between 500℃-800℃ when it is used for air dry burning.
2. Inspection at the IQC stage
After receiving the electric heating tube, the quality inspection department shall inspect its electrical performance, including:
Outer tube inspection: The outer surface is intact, bright, welded firmly, welded joints are beautiful, the shape of the elbow is well formed, symmetrical, the sealing silicone is uniform, and there is no glue impurity in the screw thread.
Power, whether the resistance is within tolerance, power (+5%, -10%), resistance value (+10%, -5%);
The insulation resistance value should be more than 1000MΩ;
Leakage current ≤0.5mA;
Carry out a water pressure test (requires that under the pressure of 1.2Mpa, there should be no water leakage or water seepage phenomenon at each welding place of the heating tube, and the pressure holding time is 5 minutes)
3. Service life
Pay attention to recording the service life of the electric heating tube. If the supplier’s warranty period is 1 year and the product can actually be used for 2 years, it means that the product quality and the supplier are trustworthy.
On the contrary, if the product is actually used for half a year under reasonable circumstances, problems will occur. The product quality is obviously not high.
Note: The electric heating tube cannot be used in violation of regulations. For example, when heating the liquid, remember not to dry it out of the liquid.
The electric heating tube we need to make must meet the design specifications, all electrical properties are within the standard range, and the service life must be up to standard.
