An easy way to identify the advantages and disadvantages of self-limiting electric heating

First, the appearance

1. Whether the stratification of each layer is eccentric.

2. The products are not limited in width and thickness, and the manufacturing difficulty of small and fine products is rather difficult. It is impossible to produce small and fine products without certain strength. The width of the product should be selected according to the diameter of the auxiliary pipe diameter, the pipe diameter is large, the electric heating bandwidth, the pipe diameter is small, the electric heating belt is narrow, so the heat transfer efficiency is high, and the thin pipe (outer diameter Ф16mm) is wide-band (12mm), contact The area is small. If a narrow belt of 7-8mm is used, the contact area is large, and it should be used differently to save electricity.

Second, the material of the PTC core tape

1. Weighing: When the same size and the same length, the material weight is better, and the material is lighter.

2. Combustion test: contact with PTC core tape with open flame, non-combustible material is good, flame retardant or flammable material is second, but it should be prohibited to use halogenated flame retardant, halogen material is flame retardant but has smoke, toxic, more flammable The material is more harmful. That is, although it is flame retardant, it is already a non-environmental product that is eliminated.

3. Odour identification: contact with PTC core tape with open flame, non-wax oily material is special PTC; waxy oily product is ordinary PTC.

4. Softness: Never use softness to distinguish between good and bad. Generally, the hardness of the material is high and the price is high. For example, low density polyethylene (LDPE) is soft, the price is low, and the temperature resistance is only 70 °C. After cross-linking, it can withstand 90 °C, while high-density polyethylene (HDPE) is hard, the price is high, the temperature is 90 °C, and the temperature is 130 °C after irradiation and cross-linking. The quality of the product should refer to the performance of the product.

Third, the insulation layer and outer sheath material

The material is best in F46, followed by other fluorine materials (such as F20, F26, etc.), and the substrate is polyolefin. The flame retardant polyolefin is divided into halogen-free flame retardant, low-smoke low-halogen flame retardant, halogen-containing flame retardant, and the flame retardant is self-extinguishing or non-flame-burning rather than non-combustible. Among them, the environmentally friendly halogen-free fuel is good. It is best to pass the ROHS certification for insulation and environmental protection. Halogen flame retardant, smoke, odor, poisonous, non-environmental materials that should be eliminated or restricted production.

Fourth, 260 ° C heat aging test, the products passed are good. Because of the internationally recognized safety certification "UL certification", the product must pass the 260 °C heat aging test, otherwise it will not pass the certification.

5. The product of 100m length is energized. The temperature difference between the first and last lines is small, the temperature uniformity is good; or the shearing, the difference of the resistance value of each part under the same conditions, the smaller the difference, the more uniform the resistance value, the better the product.

6. Place the electric heating belt in more cold water or under the temperature of 0 °C, and change the power or temperature for a long time; after taking out for 24 hours after long-term power supply, it is equivalent to the outside world before the water immersion in the electric heating belt. The power or temperature changes are compared under conditions, and the smaller the temperature change and the less the power attenuation, the better the product.

7. Compare the ratio of the starting (instantaneous) current and the steady-state working current of the product under the same conditions. The smaller the ratio, the better the product is. The general ratio is ≤5. If ≤3, it is excellent, if >5 side difference. Simply speaking, the magnitude of the starting current cannot determine whether the product is good or bad. The starting current of the product is related to the working voltage of the product, the nominal power, and the ambient temperature. Currently, the propaganda of individual manufacturers on the market is 0.5, 0.6. A/m? 10 °C is a good argument to mislead consumers. If used for antifreeze heating, the nominal power ≤10w/m?10°C, the steady state value Ie=0.045, if the starting current is 0.5A, then J 10 times, so the product is too bad, how can we say good? What?

8. Stripping the conductive core, or pulling, or bending the PTC core strip multiple times, depending on the fastness of the combination of the PTC material and the conductive core, the greater the better the better. After multiple bending, the product of the conductive core protruding from the PTC material is poor, and the product that is not extended is good, and the longer the product is extended, the worse the product is.

Nine, the conductive core, that is, the softer the two conductive cores, the better the number of roots, generally >19 / share: excellent, = 19 / share: times, = 7 / share: difference .

X. The anti-freezing power of the solar water heater inlet and outlet water and the performance of the frozen electric heating belt, especially the power size and temperature grade are different, simply mixed, or wasted electricity, or the effect is poor, it is unscientific, antifreeze The belt should adopt low temperature and low power, generally 5w/m 10 °C, and the thawing zone should choose medium temperature and high power, generally 15-25w/m? 10 °C.