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  • Tubular Heating Elements

    Highly versatile and economical Durex tubular heater elements are applied in virtually every conceivable type of heating application. They can be applied straight or bent into complex formations. They can be reliably applied to heat a multitude of liquids, gases, and solids. Tubular heaters are also used for radiant heating in open air or in vacuum atmospheres. They can be cast into, or clamped on to, metal to form heated parts. Durex Industries’ application and design engineering team are available to assist in specifying the proper heater configuration.
     

    Contact us for Engineering Assistance.

    Product Overview

    Design Features:

    • Precision helical wound nickel-chromium resistance wire provides uniform thermal profile
    • Circumferential cold pin-to-wire fusion weld ensures robust connection for long heater life
    • Compacted, high purity MgO dielectric insulation extends resistance wire life at high temperatures
    • Recompacted bends provides longer life by ensuring insulation integrity
    • UL & CSA recognized elements assures safe and reliable performance

     

    More Products In This Section

    • Straight Tubular Heating Elements
      Straight Tubular Heating Elements
      Durex manufactures standard tubular heating elements for any application. Tubular heating elements are a versatile and economical heat source for a wide variety of industrial and commercial applications. Standard diameters are .260”, .315”, .375”, .430”, .496”, and .625”. Other special sizes are available. Depending on the diameter, lengths can be…
    • Formed Tubular Heating Elements
      Formed Tubular Heating Elements
      Custom heating elements can be provided to any length, formed into any configuration and sheathed in a variety of different materials to suit your application. Likewise, the connection/termination possibilities are limited only by your imagination and the availability of components. Standard terminations include threaded stud, threaded bulk-head, screw lug, quick…
    • Manifold Tubular Heaters
      Manifold Tubular Heaters
      Durotube™ manifold tubular heating elements provide an economical, robust, and versatile heat source. These elements are commonly used to fit into milled grooves for hot runner molding systems. The precision fit optimizes heat transfer to the working surface. Durex can provide formed elements “ready to go” into your existing channel…
    • Immersion Tubular Heaters
      Immersion Tubular 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. Tubular heater assemblies are also the preferred solution for laboratory sterilizers and environmental chambers.…
    • Finned Tubular Heaters
      Finned Tubular Heaters
      Higher watt densities and increased heat transfer characteristics are achieved using the finned tubular heater design. The continuous spiral fins are attached to the heater sheath promoting rapid heat dispersion in air or liquids. The fins are constructed of steel, stainless steel, or Incoloy depending on the application requirements. All…

    Engineering Data

    TUBULAR HEATER SPECIFICATIONS

    Physical and Electrical Specifications

    Sheath Diameter +-0.005" (+-0.13mm) 0.260" (6.60mm) 0.315" (8.00mm) 0.375" (9.52mm) 0.430" (10.92mm) 0.475" (12.07mm) 0.496" (12.60mm)
    Sheath Length Maximum 404" (10,260mm) 370" (9398mm) 337" (8560mm) 329" (8356mm) 281" (7137mm) 263" (6680mm)
    Maximum Voltage 250 480 480 600 600 600
    Maximum Amperage 15 30 30 40 40 40
    Wattage Tolerance Industry Standard +5% - 10% Industry Standard +5% - 10% Industry Standard +5% - 10% Industry Standard +5% - 10% Industry Standard +5% - 10% Industry Standard +5% - 10%
    Resistance Tolerance Industry Standard +10% -5% Industry Standard +10% -5% Industry Standard +10% -5% Industry Standard +10% -5% Industry Standard +10% -5%

    Industry Standard +10% -5%

     

    Length Specifications

    Overall Sheath Length 11-20" 21-50" 51-80" 81-110" 111-140" 141-170" 171-200" 201" & up
    Sheath Length ±3/32" ±1/8" ±5/32" ±3/16" ±7/32" ±1/4" ±3/8" ±1/2"
    Heated Length ±1/4" ±1/2" ±7/8" ±1 1/8" ±1 3/8" ±1 5/8" ±1 7/8" ±2 3/8"
    Minimum Unheated 1" 1 1/4" 1 1/2" 1 5/8" 1 3/4" 2" 2 1/4" 2 1/2"

     

    CONSTRUCTION OPTIONS

    Unheated Length
    The unheated length can be varied to suit application requirements. Longer unheated sections are often used to keep the termination area cool or to focus heat generation in a specific area of the part or media being heated.

    Distributed Wattage
    Durex tubular heaters can be tailor-made to vary the watt density along the length of the heater. This aids in temperature uniformity in mold applications or to make up for heat losses close to the ends.

    Sheath Treatment and Finish
    For tubular heaters that will be field bent, please be sure to specify “full anneal” on the order. For pharmaceutical and other “clean” applications, a bright anneal finish can be supplied. Also available, depending on configuration, is sheath passivation which removes any free iron that may stain or rust the finish of the sheath.

     

    TERMINATION OPTIONS

                                        

    Type S1                                                                                          Type S2

    Threaded Stud Terminal w/Ceramic Insulator                       Threaded Stud Terminal w/Stacked Mica


                                                             

    Type L1                                                                                                           Type L2

    Screw Lug Terminal                                                                                     Screw Lug terminal 90°


                                                 

    Type D1                                                                                                                 Type D2

    Quick Connect                            Maximum 240V                                            Quick Connect 90°

     


            

    Type W

    Leadwire Terminal Assembly



     

    MOUNTING OPTIONS

    Type R Mounting Bracket


     

           

    Type K  Mounting Bracket


      

    Type F Mounting Flange

    Specify all required dimensions and tolerances.


      

    Type B Threaded Bulkhead fittings



     

    SEAL OPTIONS

     

    Type M Silicone Rubber Overmold

     

    Product Applications

    • Metal mold, die and platen heating
    • Medical and analytical device heating
    • Cast into metal parts and platens
    • Cut and seal heads on packaging equipment
    • Tank wall and pipe heating
    • Liquid immersion & circulation heaters
    • Furnace & oven heating
    • Comfort heating and freeze protection
    • Process air and gas heating
    • Thermoforming, curing, drying

     

    Application Guidelines:

    Heating Metal Parts

    Durex recommends to “press fit” the tubular element into milled groove plates for extended heater life. Ensure that all heated portions of the heater are in contact with the part. Heat transfer cement should be used to promote heat transfer. If clamps are used, they should be closely spaced and not over tightened to ensure good heater-to-part contact. Allow for up to 10% length increase due to thermal expansion during heating.

     

    Heating Liquids

    Tubular elements are typically formed into ‘U’ (hairpins) or loop type formations and either placed over the tank side or secured through a hole in the side (or bottom) of the tank. Factory installed fittings or field installed compression fittings are used to mount and seal the tubular element against the tank wall. Refer to the Immersion, Circulation and Over-The-Side Heater section of our website for other liquid heating products.

    To prevent overheating or fouling the heater element, ensure the heated portion of the tubular heater is immersed in liquid at all times. For optimal results, properly match the sheath material and heater watt density to the liquid application. Refer to the chart below for general sheath material and watt density guidelines.

     

    Heating Air & Gases

    Durex tubular heaters are robust solutions for furnace and oven heating as well as forced air and gas heating applications. Refer to the Circulation and Duct Heater sections of our website for forced air and gas heating products. Tubular elements are typically formed into ‘U’ (hairpins) or one of the multiple bend formations. They are installed through wall openings and secured with lock washers, clips, threaded fittings or mounting bracket.

                                           OVEN                                                                               DUCT                                                                                      

    For optimal results, use an Incoloy® sheath and ensure reasonable watt densities are used. Allow for 10% length increase due to thermal expansion. For horizontal installations, provide supports at least every 18” of length to avoid element sagging due to high temperatures.

     

    Radiant Heating and Vacuums

    Tubular heaters used for radiant heating typically use reflectors to direct heat energy toward the part being heated.  However, in a vacuum, heater elements operate at much higher temperatures. Therefore, reduce watt density by 20% to 30% versus air heating conditions to ensure good heater life. Aluminum sheath as well as Inconel® sheathed heaters are typically used with vacuum feed through assemblies. Vacuum leakage rates can be measured down to 8x10-8 SCCS He (3x10-6 Pa l/s).

                              RADIANT HEATING

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