Mineral insulated heating elements with two-wires

Our two-wire heating elements (internal reference CXX & BXX heaters) offer flexibility to our customer due to its various mounting options to match their specific application for example, coiling, clamping or brazing. On this page we provide more detailed information on these heaters including their properties and possible applications.

Two wire heating elements (CVX & BVX heaters)

Kamet’s two-wire elements are designed with a robust structure, featuring insulation from magnesium oxide (MGO) and protection via a flexible metal sheath, which allows for a minimum bending radius of twice the outer diameter. The two-wire heating elements closely resemble the one-wire heating elements. However, the key distinction lies in the two-wire versions, which incorporate two conductors within. These can be welded together to create a circuit. As a result, the two-wire heating element will have terminations on only one side.

These mineral insulated (MI) heating elements are equipped with a conductive cold end, typically from materials like copper or nickel, which possess significantly lower resistance values. This design facilitates easy termination by ensuring the cold end can seamlessly integrate into various setups.

The innovation in Kamet’s heating elements extends to their internal design, where seamless transitions between hot and cold sections are achieved without any change in the sheath’s outer diameter at the points where these elements meet. This is accomplished through electro-etching at the locations of internal hot/cold splices, maintaining a uniform diameter throughout.

Such a feature, along with their ability to support high power densities (>100 W/m), renders these elements highly suitable for demanding applications. The elements can extend through insulated walls without the risk of overheating, marking it suitable for a wide range of industrial applications.

Physical properties

  • Sheath: Inconel® 600 standard 304SS, 316SS, or 321SS on request
  • Insulator: ≥99.4% Compacted MgO
  • Hot Wire: Inconel® 600 standard. Nichrome 80/20 on request
  • Cold Wire: Nickel

Maximum working temperature

  • Hot Part: 1000⁰C
  • Cold Part: 600⁰C (CXX, BXX = Nickel)

Tolerances

  • Sheath Diameter: +0/-0.08mm
  • Hot Section Linear Resistance: ±10%
  • Hot Section Length: <1500mm; +0/-10% ≥1500mm; +0/-7%

Heating Liquids or Gases

Exploring the intricacies of heating liquids and gases reveals a world where precision meets practicality. Each method, whether submerging elements in liquids or coiling them for gas heating, is designed with specific power and temperature limits in mind. Kamet’s expertise shines in offering solutions that adapt to the dynamic nature of these fluids, ensuring efficiency and safety. Here’s a closer look at these methods and their technical specifications. Based on our experience, two-wire heating elements are more commonly employed in the heating of liquids or gases. For liquids, the heating elements are submerged into the liquid. In the case of gases, the heating elements are typically coiled around a cylinder, as seen in applications like gas chromatography.

Heating liquids

– Submerge directly in the liquid to be heated
– Maximum power density: <9 W/cm^2 for standing liquid
– Maximum temperature: 980⁰C

NOTE: For applications with fast moving liquids, power density can be increased. Contact Kamet for advice in this regard.

Heating gases

– Commonly coiled and inserted inside a tube where gas moves over the coils or as oven heating element for harsh environments
– Maximum power density: <4.5 W/cm^2 for standing air
– Maximum temperature: 980⁰C

NOTE: For applications with fast moving gases, power density can be increased. Contact Kamet Trading to consult.

Heating in vacuum environments

Radiant heat is one of the most common methods of heat transfer in a vacuum. Electric heaters need to be over 500°C before metal surfaces start to radiate heat away from the surface of the heater. Keeping that heat in the area of the process and away from the cold section of cable brings a new generation of efficiency to radiant vacuum process heating. The desired heating rate and required power will determine the mounting method. Vacuum applications bring particular challenges:

  • A vacuum acts like a heat trap. Until radiant temperatures are achieved the heat stays in the heater or the parts that are being heated.
  • Sensing temperatures from metal heater surfaces in a vacuum can also be difficult.

Contact us for more advice on this matter.

NOTE: For increased life time or heating uniformity, brazing or casting is recommended even if < 4.5 W/cm^2

Mounting methods

Heating elements can be mounted onto all kinds of materials. Due to its flexibility, the heaters can be bent in several shapes to transfer heat effectively. The mounting can be done by wrapping the heating element around the object to be heated, but it can also be grooved or brazed onto a surface. The chosen mounting method depends on the desired heating rate and required power.

The table below contains information on the parameters of various mounting methods for the mineral insulated heating elements.

Power Density W/cm^2Temperature ⁰CMounting Method
< 3< 980Simple wrap & loose clamping is acceptable
3 – 6< 300Simple wrap & loose clamping is acceptable
3 – 6300 – 600Must be clamped tightly to the object
3 – 6600 – 980Must be partially brazed or cast into the piece to be heated
6 – 15< 980Must be completely soldered, brazed, or cast into the piece to be heated

Kamet’s range of mineral insulated heating elements

  • CXX heaters: Two-wire mineral insulated heaters with a hot wire of INC600 or Nichrome 80/20 and a copper cold wire
  • BXX heaters: Two-wire mineral insulated heaters with hot wire INC600 or Nichrome 80/20 and a nickel cold wire. Detailed application guide for BXX.

Why do business with Kamet?

Through our partnership with ARi, we offer extensive testing and services such as vacuum brazing whereby the heater is cast into the customer’s required material.

We are on hand to answer all your question related these services and our heating elements. We look forward to hearing from you. Please feel free to contact us with your particular heating needs.


Other products in this category
Cathode heaters for ion thrustersCustom-made heatersMetal-to-ceramic heating connectorsMineral insulated heating elements with one-wireWafer HeatersMineral insulated microheaters