Decisive factors of cartridge heater quality
The quality of the electric heating pipe depends mainly on the following aspects: electrical strength, insulation, leakage current, and power accuracy
1. Electrical strength: The factors that affect the electrical strength of electric heating pipes mainly include the thickness of the insulating layer, the quality of the raw materials of the insulating layer, the length of the electric heating pipe, the radius of the bend, and the number of bends. KAWAI can generally achieve 2000V, 1 second, and 0.5mA breakdown current in the cold state withstand voltage of electric heating tubes.
2. Insulation: The main effect on the insulation of electric heating pipes is the sealing process of electric heating pipes. KAWAI can generally achieve more than 1000 megohms.
3. Leakage current: It is mainly related to the temperature of the electric heating tube, the voltage of the electric heating tube, and the heating length of the electric heating tube. An important assessment index for high-temperature electric heating pipes.
4. Power accuracy: It is mainly related to the quality of the resistance wire and the technological level of the manufacturer. KAWAI needs to perform temperature coefficient tests before mass production to determine the cold state resistance of the qualified power range.
Use and maintenance of electric heating pipes
⒈The heating part should be completely immersed in the heating medium to prevent the heat from dissipating quickly and exceeding the allowable heating temperature to damage the heating element. In addition, the lead-out part of the wiring should be exposed to the heat insulation layer of the heater or the heater, so that this part should not be overheated and damaged.
⒉ For the input power, the voltage should not exceed 10% of the rated voltage marked on various electric heating pipes. If it is applicable to lower than the rated voltage, the heat generated by the electric heating pipe will also decrease.
⒊ The terminals of tubular heater should be tightened with 2 nuts. Do not use too much force to prevent the screws from loosening and damage the electric heating element.
⒋The terminal of electric heating element should be kept clean and dry, otherwise it will reduce the insulation performance and be short-circuited. If the environment of liquid or gas such as chemical corrosion, flammable and explosive is applied, the electric heating tubular terminal should be insulated The device is strictly protected to prevent accidents.
⒌When heating some viscose and other materials, such as sodium nitrate, stearic acid, paraffin, etc., the power voltage should be lowered when heating is started to reduce the heating value of the electric heating tube. When all the liquid is melted into a liquid, it will rise to the rated voltage. Heat.
⒍ When selecting electric heating element, special attention should be paid to the heating medium. There should be no corrosive effect on the material of the electric heating shell.
Comparison of metal heating elements
One. Iron chromium aluminum (FeCrAl)
1. Large resistivity, small temperature coefficient of resistance, high use temperature, surface load slightly higher than NiCr wire, good resistance to oxidation and corrosion, and low price
2. Maximum use temperature in the air: 1000-1100 degrees Celsius
two. Cr27Al7Mo2
1. Maximum use temperature: 1400 degrees Celsius
2. Use of S and nitrogen has a shorter life than air (N, S will damage the oxide film of the heating element)
three. Nickel chromium wire (Ni15Cr60, Cr20Ni80)
1. Small resistivity, high strength at high temperature; good welding and processability; no major change in mechanical properties at high temperature
2. Maximum operating temperature: 1000-1050 degrees Celsius
four. Pure metal: (high melting point metal: Mo, W, tantalum)
Common characteristics: large electrical resistivity, high melting point, poor oxidation resistance (generally cannot be used in air). When heating, the power is unstable. Be sure to match the magnetic regulator or thyristor plus regulator. The heater voltage should be less than 100 volts.