Uneven pipe surface temperature and short-term pitting of the sheath are two common types of feedback for sheathed electric heaters in the field. The former is mostly related to power density and installation clearance, while the latter usually points to a mismatch between sheath material and medium. The following explains each item according to engineering parameters.
The sheath directly contacts the heated medium, and its service life depends on the compatibility between the material and the medium. Water and neutral solutions can use 304 stainless steel; media with more chloride ions should preferably use 316L; corrosive conditions such as acid-base tanks can be evaluated with titanium or PTFE sheaths. Before selection, the medium name, concentration, and operating temperature should be provided so the supplier can calculate the corrosion rate.
The DJR-45 type commonly uses 220V or 380V, with a single-unit power range of 1–6kW. The surface load is generally controlled at 2–4W/cm²; for heating viscous media or conditions prone to scaling, the lower limit should be taken to reduce coking. When the power density is relatively high, the sheath length should be increased accordingly or the single-unit power reduced.
This structure uses flange or threaded connections, making individual replacement convenient. During installation, the heating element should be fully immersed in the medium to avoid dry-burn areas; the terminal box should face upward or sideways to prevent liquid accumulation. For pipe heating applications, maintenance space should be reserved, and the tightening torque should be determined according to the sealing surface size.
Q: Can it be used for corrosive media? A: The medium composition must first be confirmed, and then the corresponding sheath material selected. Q: How is the heating time estimated? A: Calculate the heat based on medium mass, specific heat capacity, and required temperature difference, then estimate in combination with thermal efficiency, leaving a margin.
