Ceramaseal® Thermocouples

Ceramaseal® Thermocouple Feedthroughs for Measuring Temperatures in Vacuum or Pressure Chambers

Ceramaseal® thermocouples are manufactured with thermocouple materials or compensating material and transmit the electromotive force (EMF) generated by the application of heat to the thermocouple bead through the wall of the chamber without introducing error.

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Worth Knowing:

Ceramaseal® Thermocouple Applications

  • Furnaces
  • Power generation measurement and control
  • Aerospace
  • In-vacuum coating
  • Semiconductor processing equipment
  • Energy research
  • Industrial equipment

External instrumentation can then evaluate the strength of the EMF that is proportional to the temperature at the thermocouple bead, thus yielding a temperature measurement. Ceramaseal® thermocouple feedthroughs from CeramTec provide the necessary electrical isolation and a hermetic seal. CeramTec uses compensating wires for refractory and noble metal thermocouples. The joints between the compensating material and the true thermocouple conductor material must be thermally shielded and not exceed 250°C.

Materials, Processes, Assembly and Installation

Typical Construction of Ceramaseal® Thermocouples
(1) Contact, (2) Insulator, (3) Shims, (4) Cap, (5) Adapter, (6) Flange, (7) Spacer, (8) Conductor, (9) Contact

Ceramaseal® thermocouple feedthroughs use only inorganic materials. The insulators are made from high-purity, high-strength, low-loss alumina ceramics. Hardware metals include Kovar®, stainless steel, nickel, copper, nickel-iron alloys, cupro-nickel alloys and molybdenum. Conductor materials and contacts include Chromel®, Alumel®, Alloy 405, Alloy 426, Alloy 11, copper, Constantan® and iron. Alloy 11, copper, Alloy 405 and Alloy 426 are used as a compensation material in C, R and S feedthrough types.

Worth Knowing:

Ceramaseal® Thermocouple
Standard Specifications

  • Cryogenic temperature range: (-269°C) to 450°C
  • Internal pressure from 1x10-10 torr to 241 bar (3500 psig)
  • Thermocouple types (ANSI) C, E, J, K, R, S, T
  • Single to 20 pairs

Custom Designs and Solutions

  • 940-pin feedthrough using thermocouple materials
  • Sub D connectors using thermocouple materials
  • Single pair high-temperature cable end seal in a special plug design


ANSI Type Thermocouples Polarity °C EMK (mV)
*Not an ANSI symbol
T Copper
-200 to 350 -5,60 to 17,82
K Chromel
-200 to 1.250 -5,9 to 50,63
J Iron
0 to 750 0 to 42,28
S Platinum 10% Rhodium
0 to 1.450 0 to 14,97
R Platinum 13% Rhodium
0 to 1.450 0 to 16,74
C* Tungsten 5% Rhenium
Tungsten 26% Rhenium
0 to 2.315 0 to 37,06
E Chromel
-200 to 900 -8,82 to 68,78

Braze materials used are silver, copper, silver-copper or gold-copper alloys. Metalization processes include both refractory-metal and active-metal metalizations, depending on the size, geometry and performance requirements for the seals. CeramTec uses advanced techniques and methods to control and monitor critical processes, including 100 percent helium leak testing and x-ray measurements for metalization control.

Standard installation mountings for Ceramaseal® thermocouples include:

  • Schweißen Welding (pulse-TIG, TIG, laser, E-beam welding)
  • ISO KF flange
  • ConFlat flange
  • NPT fitting (see Pressure section)
  • 1" baseplate (see Baseplate section)

Recommended Contacts

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