Tag Archives: Mineral Insulated cable

TUS & SAT Thermocouples for heat treatment

Description of the Thermocouples

When two different materials are welded together to make a junction and heated up, an electromotive force (EMF) is generated make the measurement of temperature possible.

The EMF generation uses the Seebeck effect.

The thermocouples measure temperature differences.

The EMF are generated in Temperature gradients.

The sensitivity of the thermocouple is the sum of the thermoelectric power of each conductor.

The advantage of a higher EMF means a better temperature resolution.

The thermocouples are standardized. The basic values of the EMF and the tolerances are laid down in the IEC584-1+2 standards.

Thermocouples cover a temperature range from -200°C to +2300°C.

The essential THERMOCOAX thermocouple construction is that both conductors, insulation and metal protecting sheath are combined as a cable :

  • The two wires make the thermoelectric pair
  • The mineral insulator is a highly compacted powder
  • The continuous metal sheath provides the mechanical and chemical protection of the pair.


At the end, the cores and the sheath are welded and constitute the junction.



For the aerospace industry and more recently for the automotive industry, the heat treatment of high end materials has to conform to the ASM 2750 E and CQI-9 standards respectively.

Those standards give the pyrometric requirements for thermal processing equipment used for the heat treatment of metal parts.

The System Accuracy Tests (SATs) and the Temperature Uniformity Surveys (TUS) are key parts of state of the art heat treatment operations.

The SAT is performed to assure the accuracy of the furnace control and recording system in each controlled zone.

TUS shall be performed to measure temperature uniformity and to establish the acceptable work zone and qualified operating temperature range(s).

Thermocouples shall be installed in the thermal processing equipment within the work zone or as close as possible to it.

The load sensors are attached to or in contact with production material.

Those temperature homogeneity standards concern atmospheric pressure (air) furnaces as well as vacuum furnaces.

The homogeneity of the furnace temperature depends on the quality and accuracy of the measuring instruments used.

When choosing survey TCs, their maximum correction factor needs to be below the required specification and tolerances of the furnace.

To meet the demanding requirements of heat treatment applications, thermocouple types R / S / B / J / T / E / K / N / C have to conform to precise calibration requirements, especially in terms of tolerance.

Tolerance values are governed by standards, such as NF EN 60584-1 and ASTM E230.

The ASTM E230 “Special tolerance” is more restrictive than the NF EN 60584 “Class 1” below 375°C.

Tolerance values are given as a deviation in degrees Celsius or a function of temperature. The larger value is applicable.

For example, for K type thermocouples, the special tolerance value to conform to the ASTM E230 is +/-1.1°C or 0.4%

SAT & TUS thermocouples must be calibrated every 6 months for Type B, R & S and every 3 months for N & K thermocouples. The allowed error is +/- 1.1 ° C or + / 0.4% for SATs thermocouples and +/- 2.2 ° C or +/- 0.75% for TUS thermocouples.

We also talk about tolerance classes for thermocouples.

Thermocoax inspects the whole thermocouple production chain.

The mineral insulated cables that represent the core of the technology, are manufactured in the French factory of Athis de l’Orne (61).

Furthermore, THERMOCOAX has its own calibration laboratory certified by a national COFRAC accreditation No.2-1384 with an international recognition.

If required, we can deliver a COFRAC calibration certificate for each thermocouple manufactured.

  • Calibration Laboratory – COFRAC Certified
  • CERTIFICATE No. 2-1384 rev. 3
  • International recognition
  • Range of validity accessible on the COFRAC website



To offer the full range of temperature calibration points for heat treatment manufacturing, we use two different calibration process: The fixed points calibration and the calibration by comparison.




THERMOCOAX owns a wide range of means for calibration by comparison, as well as by fixed points. This variety of equipment allow us to perform comparisons between the different measuring instrument in order to ensure the validity of our results and our uncertainties. We also frequently perform inter-laboratory comparisons in accordance with the international standard EN ISO/IEC 17043.

Our team of specialists with our 60 years of experiences in thermal applications and in the management of regulatory requirements of the aerospace and automotive industry, gives us an international reputation.

The quality of the thermocouples, the homogeneity of the production and a high-performance calibration process, make it possible to improve reliability and efficiency of the heat treatment plants.




Heating elements systems for industries

We manufacture heating elements from Mineral-insulated cables for many industrial applications :

  • Heating elements for Metal transformation industries, forging, and funderies

We offer specific heating plates, immersion heaters, heated nozzles, and trace heating solutions, complying with a wide variety of requirements for different industrial needs.

  • Heating elements for Metal coating deposition industries

We manufacture heating plates complying to the heating uniformity requirements of deposition processes.

We offer heating shells to accurately process only a portion of the workpiece.

We manufacture ovens of different sizes and powers that fit over the main machinery manufacturer processes.

  • Heating elements for Gas transfer lines and injectors for analysis industries

PEMAC - ensemble interface

Through our expertise in high level, added value heating elements, we develop shielded IR sources for an optimum plastic welding process :

  • Thermocoax shielded IR sources are dedicated to the welding processes of specific thermoplastic, such as PEEK.

Those IR sources are mainly used in the automotive industries to meet the requirements of plastic clean welding processes requested by automotive standards.

The shield protects the Mineral-insulated cables from corrosion.

This process can be used for welding 3D complex parts.

To complete our range of heating elements, we are specialised in thermocouples for temperature control and monitoring :

  • We are COFRAC-certified for the calibration of thermocouples.
  • We offer a complete range of Thermo-couples up to 2 300°C.
  • For severe environments, we suggest our Multi cores transmission cables.
  • We also have a full range of heating elements for applications < 500°C: heating mats, heating jackets availble in Silicon or glass silk material, drum heaters, heated hoses, and more.

PEMAC - Transmission cable- THERMOCOAX 1

For more information on this product range, please complete this form aside to download our ISOPAD brochure 

Space market

At THERMOCOAX, we manage all steps of entire space projects from the design through the qualification and up to the final product.

We have built a strong pedigree of heating systems up to 100 volts for Heat pipe applications, 3 to 10 watt Catalyst Bed heater for hydrazine or green propellant thrusters, heating devices and magnetic coils for electrical Hall effects thrusters.

SPACE - Catalyst Bed Heater - 1

SPACE - catalyst bed heater - 2

THERMOCOAX is also a provider of high temperature sensors, such as the 3800F sensors supplied to the ISS's Material Space Laboratory or for measuring the skin of the space probe during re-entry to the atmosphere. The technology offers exceptional possibilities of power and small dimensions. Devices  as small as 0.019” diameter enabling improved integration. Our Talent comes from the Mineral Insulated Cable we have been manufacturing for nearly 60 years, our precious know how which we continue to keep secret.


Learn more about our space products, below :

High tech aeronautic solutions

THERMOCOAX Aeronautic Thermal Solutions :

We manage all steps of entire aeronautic thermal projects from the design through qualification and up to the final product.

Our mission is to develop state-of-the art, complete aeronautic solutions and this is through advanced innovation from conception, to prototype development right the way through to production.

We offer tailor-made anti-icing, heating tools and temperature sensor systems, providing our aeronautic customers with safer, cleaner and the most cost effective solutions.

Mineral Insulated Cable for Aeronautic Applications :

You can find thermocouples:

  • On aeronautic gas engines and APU test benches 
  • Temperature monitoring on aeronautic braking system


In the aeronautic division, we also produce Heating elements :

  • For anti-icing system and heat treatment for pitot tubes, angle of attack probes, waste water drain masts and anti-icing screens for helicopter turbine air inlets.
  • PEEK composite heating tools for curring, shaping and welding aeronautic parts. We can shape the heating cable 3D to fit with the complex shape of the customer’s part


Other aeronautic specific sensors manufactured :

  • Overheat sensor to detect a hot air leakage on the bleed system
  • Fire detector to monitor the integrity of electronics installed on aeronautic engines or in nacelles.


THERMOCOAX Aeronautic Expertise :

THERMOCOAX has acquired a great deal of skills and expertise that are endorsed by every demanding commercial and military aeronautic platforms.

With a good 20 years experience in the aeronautic industry, THERMOCOAX is an international  supplier for many aeronautic programs :

  • MD80, A320,  A340, A380, Falcon Jet, Embraer Legacy, B787, 
  • Mirage, Rafale, SAAB Grippen, JSF F35, A400M
  • Eurocopter NH90, Boeing Apache

We will supply  new programs : KC390, Cseries, C919, Dassault SMS, MRJ, Typhoon

THERMOCOAX participates in many airframes programs.


AERONAUTIQUE - thermocouple de frein - THERMOCOAX

From this cable THERMOCOAX manufactures :
  • Thermocouples for on board helicopter gas engines and APU,Test benches and the BTMS (brake temperature monitoring system)
  • Heating elements for anti-icing system and heat treatment : heating systems for pitot tubes, Angle of Attack probes, waste water drain masts and Anti-icing screens for helicopter turbine air inlets.
  • Specific Sensors : Blade tip clearance/tip timing Capacitance sensors up to  1400°C without cooling systems, Debris monitoring sensors for air inlet and exhaust gas paths.


Learn more about our aeronautic products, below