High temperature thermocouples are essential for accurate temperature measurement in the most demanding industrial environments. At Cleveland Electric Laboratories, we’ve been engineering thermocouples for high temperature applications for over 100 years, providing reliable measurement solutions that withstand conditions where conventional sensors fail.

Our very high temperature thermocouples are designed for extreme environments reaching up to 2,700°F (1,482°C), delivering precise high temperature measurement using thermocouple technology across aerospace, glass manufacturing, steel processing, and power generation industries.

Platinum Composite Sheath Thermocouples

Platinum Composite Sheath Thermocouples enable flexible and responsive high temperature measurement with a compact and cost-effective package design in environments where Base Metal Mineral Insulated Metal Sheathed cable would be unable to survive. These very high temperature thermocouples are an excellent option when an extended length probe is necessary but only a portion of the sheath length is exposed to extreme heat.

high temp thermocouple

Technical Specifications

Specification Details
Calibration Types B, R & S
Sheath Diameters 0.020″ – 0.250″
Temperature Range Up to 2,700°F (1,482°C)
Termination Options Exposed leads, plugs/jacks, soft wire transition
Certification Individual or lot certification available
Primary Applications: Gas turbine testing, aerospace engine monitoring, industrial furnace control

To achieve optimal performance, Cleveland Electric Laboratories begins with two noble metal thermocouple wires that extend the full length of the thermocouple in one continuous piece. Crushable ceramic insulators are then threaded over the conductors. This insulation is typically made of high-purity Alumina, but Hafnia or other specialized insulations can be used depending on the application and maximum operating temperature.

The innovative sheath design features two distinct sections: the length exposed to full temperature is constructed from Platinum or Platinum/Rhodium blend, while the remainder uses Inconel. These sections are fused together to create a seamless transition, and the wire/insulator assembly is inserted into the sheath. The entire assembly is then prepared and compacted, resulting in a longer, slightly thinner thermocouple wire free of internal voids.

Performance Advantages

  • Extreme flexibility – bendable to radii down to 4X sheath diameter
  • High thermal conductivity for rapid response times
  • Chemical resistance to most atmospheres and chemicals
  • Mechanical durability against shock and vibration
  • Extended service life with exceptional accuracy and low drift

Thermocouples for Glass Industry Applications

Temperature control and purity are critical factors in glass manufacturing, whether producing laboratory glassware, windows, beverage containers, or specialty glass products. Our thermocouples for high temperature applications are used throughout the glass manufacturing process, including melting, refining, feeder channels, working end processing, and combustion space monitoring.

high temperature measurement using thermocouple

Technical Specifications

Specification Options
Calibration Types B, R & S
Wire Gauge 24 AWG (Standard)
Protection Tubes Alumina, Mullite, Silicon Carbide, Re-Crystallized Silicon Carbide, Inconel
Termination Options Exposed leads, plugs/jacks, soft wire transition
Special Coatings Platinum thimble, platinum spray coating
Applications: Fore hearth, melter crown/bottom/side wall, regenerator crown, refiner, distributor sump, spout, throat, glass level, glass furnace

In glass manufacturing, temperature variations as small as 2°F can completely disrupt operations and render machinery inoperable. High temperature measurement using thermocouple technology must provide exceptional accuracy and reliability, particularly in areas reaching temperatures of 2,700°F (1,500°C) where thermocouple replacement is extremely challenging.

While standard refractory materials work well in combustion spaces and above the glass surface (crown areas), direct contact with molten glass requires specialized materials. Molten glass attacks and gradually dissolves conventional sheath materials, making Platinum and Platinum/Rhodium alloys essential for glass immersion applications.

Key advantages of our platinum-based systems:

  • Non-wetting properties – molten glass doesn’t adhere to platinum surfaces
  • Chemical inertness – resistant to glass attack and dissolution
  • Easy removal – prevents glass buildup affecting measurements
  • Extended life – minimizes costly downtime and replacement

Glass Immersion Thermocouples: Manufactured with Type S, R, or B conductors for robust, very high temperature thermocouple applications. Available with various insulating materials and protection tubes designed for extended service campaigns in molten glass environments.

Protection Systems: Platinum-coated protection tubes, pure platinum thimbles, and platinum spray coatings for enhanced durability.

Ready to solve your high temperature measurement challenges?

Contact Cleveland Electric Laboratories for expert consultation on thermocouples for high temperature applications. Our technical team provides the specialized knowledge and proven solutions your critical processes demand.

Additional High Temperature Thermocouple Solutions

Noble Metal Thermocouples (Types R, S, B)

For the most extreme high temperature applications, our noble metal thermocouples provide unmatched performance and accuracy:

Type R (Platinum-13% Rhodium/Platinum)

  • Temperature range: 0°C to 1,600°C (32°F to 2,912°F)
  • Excellent stability and accuracy
  • Ideal for precision laboratory applications

Type S (Platinum-10% Rhodium/Platinum)

  • Temperature range: 0°C to 1,600°C (32°F to 2,912°F)
  • NIST standard for high-temperature calibration
  • Superior long-term stability
high temp thermocouple

Type B (Platinum-30% Rhodium/Platinum-6% Rhodium)

  • Temperature range: 600°C to 1,800°C (1,112°F to 3,272°F)
  • Highest temperature capability
  • Self-compensating at room temperature

Tungsten-Rhenium Thermocouples

For ultra-high temperature applications in inert or vacuum environments:

  • Temperature range: Up to 2,300°C (4,172°F)
  • Applications: Vacuum furnaces, spacecraft, research applications
  • Advantages: Highest temperature capability available

Trusted by Industry. Built by CEL.

Our thermocouples are engineered for high-temperature measurement in the world’s toughest environments.

Frequently Asked Questions About High Temperature Thermocouples

Very high temperature thermocouples can measure up to 2,300°C (4,172°F) using tungsten-rhenium alloys in vacuum or inert atmospheres. For oxidizing atmospheres, platinum-rhodium thermocouples (Type B) can reliably measure up to 1,800°C (3,272°F). Cleveland Electric Labs engineers thermocouples for high temperature applications based on your specific environmental conditions and accuracy requirements.

Selection depends on maximum temperature, atmosphere type, accuracy requirements, and mechanical constraints. Type K works to 1,260°C in most environments, while noble metal types (R, S, B) handle extreme temperatures up to 1,800°C. For ultra-high temperatures above 1,800°C, tungsten-rhenium or specialized refractory metal thermocouples are required. Our applications engineers provide consultation for optimal sensor selection.

Common failure modes include oxidation of thermocouple wires, contamination from process materials, mechanical damage from thermal cycling, and grain growth at extreme temperatures. High temperature measurement using thermocouple technology requires proper material selection, protective atmospheres, and appropriate sheath materials to maximize service life.

Standard base metal thermocouples (Types J, K, T) are limited to temperatures below 1,260°C. For temperatures above this range, noble metal thermocouples or specialized high-temperature alloys are required. Using standard thermocouples beyond their rated temperature causes rapid failure and inaccurate measurements.

Thermocouple calibration frequency depends on operating temperature, atmosphere, and accuracy requirements. Thermocouples for high temperature applications operating above 1,000°C should be calibrated every 6-12 months, while those in extreme conditions may require quarterly verification. Cleveland Electric Labs provides NIST-traceable calibration services for all high-temperature applications.

Protection strategies include ceramic or metallic protection tubes, controlled atmospheres, proper installation techniques, and regular maintenance. For glass industry applications, platinum coatings prevent glass attack. In steel applications, protective wells isolate sensors from molten metal contact. Our engineering team designs application-specific protection systems.

Yes, Cleveland Electric Labs specializes in custom very high temperature thermocouples designed for unique applications. We engineer sensors with specific geometries, materials, and performance characteristics based on your temperature range, environmental conditions, installation constraints, and accuracy requirements. Our century of experience enables solutions for the most challenging high-temperature applications.