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, asphalt, petroleum products, plating chemicals, molten salt baths, grease, gas or grape juice. Various sheath, screw plug, and corrosion-resistant hardware materials are available. NEMA enclosures for all moisture and explosion-proof conditions, as well. Optional thermocouples for control or high limit protection, plus a full range of thermostatic controls, can also be provided.
A wide variety of standard design configurations and custom designed solutions are available.
Contact us for Engineering assistance.
No thermostat or sensor included in base models. Contact us for custom designed engineering assistance.
2" Standard Screw Plug - NEMA 1 Enclosure - 5 DAY LEADTIME!
2 1/2" Standard Screw Plug - NEMA 1 Enclosure - 5 DAY LEADTIME!
Typical Screw Plug Immersion Heater Applications:
- Boilers & Water Heating
- Clean & Process Water
- Freeze Protection & Winterizing
- Heat Transfer Systems
- Lube & Fuel Oil Heating
- Parts Cleaning Solutions
- Plating & Finishing Chemicals
- Temperature Control Units
- Wash Systems
- Wax Heating
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.
Screw plug immersion heaters are constructed of hairpin bent tubular heater elements brazed or welded into threaded screw plugs. These heaters are inserted through a threaded hole or through a threaded coupling attached to a tank or vessel. An electrical enclosure is installed to protect the heater terminals.
Screw Plug Immersion Heater Design Features
Standard Designs 1", 1 1/4 ", 1 1/2 ", 2", 2 1/2 " NPT Screw Plugs
- Easy fit into most any application
- Optional 1 1/2", 3" & 4" NPT plugs also available
Wide Variety of Material, Enclosure, Control and Power Rating Options
- Provides the optimized solution for your needs
Brazed or Welded Construction
- Ensures a pressure tight seal
Integral Thermostats or Thermocouple
- Allows integral control or temperature monitoring
- Provide longer life by ensuring insulation integrity
c-UL Component Recognition Available
- Assures safe and reliable performance up to 600V
Process Heater Brochure PROC-BROC-0912- 7MB
Standard Screw Plug Immersion Heater Designs - 4-3-16 - 520KB