U-Shaped Liquid Tubular Heater
Industrial Heaters

U-Shaped Liquid Tubular Heater

The U-shaped tubular heater for liquids encloses a nickel-chromium resistance heating wire centered within a metal tube, with insulation and thermal conductivity achieved by compacting high-purity magnesium oxide. After bending the tube into a U shape, it can be directly immersed in water, cleaning solutions, heat transfer oil, or fuel oil, with both terminals located outside the container. The surface load, sheath material, and total power must be designed according to the thermal conductivity, viscosity, corrosiveness, target temperature, and liquid flow conditions of the medium. During operation, the entire heating section must remain fully submerged and be equipped with a temperature controller, independent over-temperature protection, and low-liquid-level power-off interlock.

Basic Structure
Nickel-chromium resistance wire + compacted high-purity magnesium oxide + metal tube sheath
Structure Form
U-shaped double-ended immersion heating tube
Common Voltage
220 V / 380 V AC; special design up to 480 V
Power Supply Method
Single-phase or three-phase, wired according to the number of components, voltage, and total power
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Product highlights

  • The U-shaped double-ended structure facilitates installation from the side wall or top of the tank or container, with external wiring completed outside.
  • Copper, 304 / 316L / 321 stainless steel, Incoloy 800 / 825 sheath can be selected according to water quality, oil type, and corrosion conditions.
  • Water heating uses 6–10 W/cm², light fuel oil 2–4 W/cm², heavy oil or high-viscosity medium 1–2 W/cm².
  • 6.5 / 8.5 / 10 / 12 / 14 mm tube diameter, as well as tube length, U-shape spacing, cold end, and mounting parts can be configured according to the diagram.
  • Low-liquid-level power-off, over-temperature limitation, grounding, and leakage protection collectively prevent dry burning, electric shock, and medium overheating.

Technical specifications

Basic Structure
Nickel-chromium resistance wire + compacted high-purity magnesium oxide + metal tube sheath
Structure Form
U-shaped double-ended immersion heating tube
Common Voltage
220 V / 380 V AC; special design up to 480 V
Power Supply Method
Single-phase or three-phase, wired according to the number of components, voltage, and total power
Common Pipe Diameters
6.5 / 8.5 / 10 / 12 / 14 mm
Sheath Material
Copper, AISI 304 / 316L / 321 Stainless Steel, Incoloy 800 / 825
Water Heating Surface Load
6–10 W/cm²
Light Fuel Oil Surface Load
2–4 W/cm²
Heavy Oil and High Viscosity Medium Surface Load
1–2 W/cm²
Power Tolerance
+5% / -10%
Dielectric Strength
1500 V
Withstand Voltage Test
Maximum 10 bar, actual working pressure depends on the installation parts and vessel design
Size Configuration
The total tube length, U-shaped spacing, bending radius, heating section, cold end, immersion depth, and mounting parts are designed according to the drawing.
Installation Method
The element is directly immersed in liquid and can be equipped with flanges, threaded joints, nozzles, mounting plates, or terminal boxes.
Minimum Immersion Depth
The entire heating section must always be covered by liquid, and the U-shaped bend should be at least 50 mm below the liquid surface.
Container Clearance
Maintain at least 25 mm clearance between the sheath and the container, and at least 50 mm clearance from bottom deposits
Liquid Level Protection
Install an independent low-level switch or float switch; cut off heater power when the liquid level is below the safety line
Temperature Control
Use a thermostat and an independent over-temperature limiter; the temperature sensor should be located below the minimum liquid level but above the bottom of the heater
Electrical Protection
The metal sheath is reliably grounded, with overcurrent, short-circuit, and leakage protection configured to match the rated current
Maintenance Requirements
Regularly remove scale, oil residue, and deposits; in scaling conditions, reduce surface load to control sheath temperature
Typical Applications
Water tanks, cleaning equipment, boilers, storage tanks, industrial baths, food equipment, heat transfer oil tanks, and fuel oil preheaters
Selection Parameters
Provide the medium name and composition, initial/target temperature, capacity, heating time, working pressure, power supply voltage, power, installation diagram, liquid level changes, and corrosion conditions
Industrial Heaters

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