Immersion Heaters

----New Immersion Heaters Image.jpgDurex Industries has over 30 years of experience in the application, design, and manufacturer of robust industrial tubular immersion (submersible) heaters and process assemblies. We have thousands of immersion heater standard designs for quick field replacements and convenient ordering. Durex also has extensive experience with custom designed electric immersion heaters for storage tanks, reservoirs, and circulation flow applications.

Industrial immersion heaters are used for direct liquid immersion heating applications. They are constructed of one or more heater elements brazed or welded into various types of mounting fittings. Standard and custom engineered electric immersion heater designs are available for tailored solutions to your thermal application requirements.

immersion heater types

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Screw Plug Immersion Heaters

Screw plug immersion heaters are used in almost every liquid heating application imaginable, including water, mild solutions, detergents, vegetable oil, aqueous solutions, tar and asphalt, petroleum products, plating chemicals, molten salt baths, grease, gas or grape juice. Various sheath, screw plug and corrosion-resistant hardware materials are available.

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Flange Immersion Heaters

Flanged immersion heaters are constructed of hairpin bent tubular heater elements brazed or welded into ANSI standard flanges or plate flanges of various shapes and sizes. ANSI flange heaters are typically used for large volume, high power and/or higher pressure applications.

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Over-The-Side Immersion Heaters

Over-the-side immersion heaters are designed for the robust requirements of corrosive chemicals, viscous (potentially contaminated) fluids, and rinse and process water heating.

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Pipe Insert (Dry Well) Heaters

Screw plug and flanged immersion heaters can be used to heat a "dry well" in a tank. This provides tank heating, while facilitating easy removal of the heater without draining the tank contents.

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Tubular Immersion Heaters

Tubular immersion heaters are commonly used in radiant and immersion heating applications such as infant incubators where a formed tubular heater warms the air flow and an immersion tubular heater assembly vaporizes water to provide humidity.

typical immersion heater applications

Pharmaceuticals, Food and Beverage Industries:

  • Batch processing
  • Brew kettles
  • Heat transfer systems and reactors
  • Milking & dairy systems
  • Ovens
  • Packaging equipment
  • Spray dryers and drying systems
  • Sterilizers
  • Transfer lines
  • Vats

Oil, Gas, Petrochem, Chemical Industries:

  • Air dryers
  • Heat transfer systems
  • Lube and pump systems
  • Process gas heating
  • Process plants
  • Reactors
  • Storage Tanks
  • Reservoirs

Power Industry:

  • Fuel gas and fuel oil heating
  • Flue gas and ESP heating
  • Storage Tanks
  • Reservoirs
  • Water wash systems

Primary and Secondary Metals Processing:

  • Autoclaves
  • Heat transfer systems
  • Heat treat baths
  • Primary and secondary metals furnaces

Application Guidelines

The goal is to optimize the heater configuration to ensure the longest life possible while minimizing overall product and life cycle costs. The general temperature, sheath material and watt density guidelines below can aid in proper heater selection for some common liquids. Contact Durex for further assistance.

Liquid Max. Operating Temps °F (°C) pH Level and/or Concentration Recommended Sheath Material Typical Plug Material Max. Watt Density W/in2(W/cm2)
Clean, Potable Water
212 (100) Neutral (pH 6 to 8) Copper Brass 60-90 (9.5-14)
Process Water & Weak Solution 212 (100) pH 5 to 9; 2-3% Incoloy®, 304SS Steel or 304SS 48 (7.5)
Demineralized, Deionized Water 212 (100) Neutral 304SS or 316SS (passivated) 304SS or 316SS 60 (9.5)
Weak (Acidic) Solutions* 210 (100) Up to 5-6% Incoloy®, 316SS Steel 48 (7.5)
Mildly Corrosive (Acidic) Solutions* 180 (80) 5-15% Incoloy®, 316SS 304SS or 316SS 20-30 (3.5)
Severely Corrosive (Acidic) Solutions* 180 (80) >15% Incoloy®, titanium, Teflon® 304SS or other 15-16 (2.5)
Caustic Soda 10% 200 (100) pH 14; 10% Incoloy® Steel 20-23 (3.5)
Caustic Soda 50% 250 (120) pH 14; 50% Incoloy® Steel 16 (2.5)
Fuel Oil 1 & 2; Kerosene Lube Oil SAE 10 to 30 200-250 (95-120) - Steel Steel 20-23 (3.5)
Fuel Oil 4 & 5; Lube Oil SAE 40 to 50 200-250 (95-120) - Steel Steel 15-16 (2.5)
Fuel Oil 6 & Bunker C 160 (70) - Steel Steel 6-8 (1.2)
Hydraulic Oil 100 (40) - Steel Steel 15-16 (2.5)
Ethlyene Glycol 300 (150) - Steel Steel 23-30 (3.5-4.5)
Glycerine 500 (260) - Incoloy® Steel 8-10 (1.5)
Molton Salt Bath 800 (425) - Steel, 321SS, Monel® Steel 23-30 (3.5-4.5)
Paraffin Wax 150 (65) - Steel or 304SS Steel 15-16 (2.5)
Molasses 100 (40) - 304SS or 316SS 304SS 4-5 (0.7)

* Sheath material and watt density dependent on type of acid, concentration, temperature, aeration, movement, etc.

  • Please note that the user accepts full responsibility for validating that a heater is suitable for a given liquid or gas heating application.
  • Ensure that heater elements are completely covered in liquid AT ALL TIMES. Failure to do so may cause the heater elements to operate in open air and fail prematurely, or worse, lead to ignition of flammable vapor mixtures, causing serious personal injury and equipment damage. Liquid level sensors are highly recommended.
  • Durex recommends the use of a thermostat or process controller as well as a high limit sensor and FM approved safety controller to prevent unexpected over temperature conditions.

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