In accordance with JB/T 2379-2016 "Metal Tubular Heating Elements" and GB/T 10067.1-2019 "Basic Technical Conditions for Electric Heating and Electromagnetic Treatment Devices," the cold insulation resistance of a sheathed electric heater at rated voltage shall not be less than 50 MΩ, and it shall withstand a 1.5 times rated voltage test for 1 min without breakdown. Based on the above general requirements, the FJR-60 model has been specifically designed in terms of sheath material, terminal enclosure protection, and temperature control interface, making it suitable for low-temperature heat tracing and local heating stations of concern to on-site operation and maintenance personnel.
The sheath uses a 304 stainless steel seamless tube, with wall thickness uniformity controlled within ±0.1 mm. Common outer diameters are φ12 and φ16, and it can be bent and formed according to the shape of the heated body to fit installation on pipes, valve bodies, or tank walls. The terminal enclosure has an IP65 protection rating, with an M20×1.5 internal thread at the cable entry. The sealing ring withstands temperatures from -40 ℃ to 200 ℃, reducing terminal oxidation in humid and dusty environments.
When the medium is static air, the recommended power density should not exceed 2.5 W/cm²; in flowing liquid, it can be relaxed to 5 W/cm². The FJR-60 model has a single-unit power range of 0.5–6 kW, and the surface heating temperature ranges from 80 ℃ to 350 ℃ depending on power density and heat dissipation conditions. During operation and inspection, the sheath surface temperature should be measured; if the deviation from the design value exceeds ±15 ℃, the supply voltage or medium flow condition must be checked.
Standard equipment includes K-type or PT100 temperature sensing elements, which can be connected to external temperature control instruments for closed-loop control, with a temperature control accuracy of approximately ±1 ℃. The control cabinet is provided with an RS-485 interface and supports Modbus protocol connection to a host computer, facilitating centralized viewing of operating current and temperature curves of multiple heaters in the duty room.
Commonly used in scenarios such as heat tracing of analyzer sampling tubes, bottom insulation of small storage tanks, and local heating of dust collector ash hoppers. Daily inspection focuses on three items: whether the sheath has local overheating discoloration, whether the terminal connections are loose, and whether the insulation resistance is below 1 MΩ. During shutdown maintenance, use a 500 V megohmmeter to retest the insulation; if it is below the limit, investigate moisture or sheath damage.
