Ordinary electric heaters are directly exposed to the medium, and the metal sheath is susceptible to corrosion, scaling, or mechanical impact; protective sleeve electric heaters insert the heating element into a metal protective sleeve, isolating the element from the medium. The HGR-18 type is designed in accordance with JB/T 2379-2016 and GB/T 34662-2017. The protective sleeve is detachable, making it easy to clean and replace the heating core, and it is suitable for low-temperature fluid heating scenarios.
Before installation, confirm the protective sleeve material (commonly 304 or 316L stainless steel), pipe diameter and length, heating power, and voltage level. The HGR-18 type commonly has a power range of 1kW to 6kW, voltage of 220V or 380V, and protective sleeve outer diameter of Φ12mm to Φ20mm. Please check that the interface thread specification (such as G1/2, G3/4) matches the on-site pipeline to avoid seal failure caused by forced installation.
If the heating time is noticeably prolonged, the current is lower than the rated value, or the protective sleeve surface temperature rises abnormally, first check whether the heating core is open-circuited and whether there is water accumulation or scaling inside the protective sleeve. After shutdown, measure the heating core resistance. If the deviation from the factory value exceeds 10%, replacement is recommended. Note: Do not remove the protective sleeve while it is energized.
Regularly clean attachments on the outer wall of the protective sleeve, check whether the wiring terminals are loose, and measure the insulation resistance (should not be less than 1MΩ). If the heating medium is prone to coking, shorten the inspection cycle. When replacing the heating core, applying thermal conductive silicone grease helps improve heat transfer, but it is necessary to confirm that the silicone grease temperature resistance grade meets the working conditions.
Compared with fixed-sleeve heaters, the detachable protective sleeve structure facilitates later maintenance and reduces downtime; compared with direct immersion heaters, the protective sleeve can isolate corrosive media and extend element life. Model selection should be comprehensively judged based on medium characteristics, pressure, temperature, and installation space.
