Thermocouples

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Thermocouples built around the measurement environment

Thermocouple selection starts with temperature range and atmosphere, but the finished assembly is usually determined by junction style, sheath material, diameter, insertion length, lead protection, termination, and documentation requirements.

Thermometrics builds base-metal and noble-metal thermocouple assemblies for industrial process control, aerospace testing, validation work, heat-treat programs, and OEM equipment where standard catalog probes do not fit the application.

Types K, J, T, E, N, R, S, and B are available in grounded, ungrounded, exposed, duplex, mineral-insulated, protection-tube, wire-sensor, surface-mount, and head-style constructions.

Thermocouple product family with mineral-insulated probes, armored leads, plug assemblies, and surface sensors

Thermocouple assembly family

Common mineral-insulated, armored, plug-and-lead, head-style, and surface thermocouple formats.

Types of Thermocouples

Builds are commonly specified to ASTM E230 and IEC 60584 tolerances, with standard or special limits of error depending on thermocouple type and application requirement.

Type K

-328 to 2282°F (-200 to 1250°C). Widest range; avoid sulfur environments.

**ASTM: -328 to 2300°F

View Type K guide

Type J

32 to 1382°F (0 to 750°C). Vacuum, oxidizing/reducing, or inert atmospheres.

ASTM: 32 to 1400°F

View Type J guide

Type T

-454 to 700°F (-270 to 370°C). Moisture resistant and very stable at low temps.

**ASTM: -328 to 700°F

View Type T guide

Type E

-454 to 1600°F (-270 to 870°C). Highest EMF output; good for cryogenic use.

**ASTM: -328 to 1600°F

View Type E guide

Type N

-454 to 2300°F (-270 to 1260°C). Oxidizing, inert, or dry reduction atmospheres.

ASTM: 32 to 2300°F

View Type N guide

Type R

-58 to 2700°F (-50 to 1480°C). Stable in oxidizing or inert atmospheres.

ASTM: 32 to 2700°F

View Type R guide

Type S

-58 to 2700°F (-50 to 1480°C). For continuous high-temperature use.

ASTM: 32 to 2700°F

View Type S guide

Type B

1475 to 3270°F (800 to 1800°C). Clean air service; avoid reducing atmospheres.

ASTM: 1100 to 3100°F

View Type B guide

Temperature Range & ASTM Tolerance Notes

ASTM Range

The ASTM E230/E230M range shown indicates where standard or special limits of error can be validated under the standard.

Documentation

Calibration and tolerance documentation depends on the requested temperature points, thermocouple type, materials, and applicable standard.

Testing Scope

In-house calibration capability is generally -196°C to 1200°C (-321°F to 2192°F). Other points can be reviewed for outside calibration or special testing.

** Temperatures outside the standard ASTM range may still be measurable at low temperatures when they fall within the practical limits of the thermocouple type. These applications require additional validation testing to confirm performance at the required operating conditions. Please contact one of our sales representatives to review your temperature range, application, and testing requirements.

Junction Styles

  • Grounded: Wires and sheath welded together for fast response; more susceptible to electrical interference.
  • Ungrounded: Wires welded together but insulated from the sheath; better for noisy environments.
  • Exposed: Wires welded and directly in the process; fastest response but more prone to corrosion.
  • Dual Ungrounded: Dual elements insulated from the sheath and from each other.

Information to Share for Quoting

  • Thermocouple type, temperature range, and required tolerance class
  • Junction style, sheath diameter, insertion length, and process connection
  • Lead wire, connector, head, armor, or transition details
  • Environment constraints such as sulfur, vibration, abrasion, or washdown exposure
  • Calibration, traceability, or documentation requirements

Where These Thermocouple Builds Are Commonly Used

  • General industrial process control and replacement service
  • Validation, profiling, and heat-treat survey programs
  • Plastics, packaging, and OEM machinery fit-up
  • Gas turbine, aerospace, and high-temperature furnace work
  • Surface, tube-skin, and distributed multi-point measurement

Browse Thermocouple Product Pages

Select the thermocouple construction by service condition: high-temperature MI cable, head-style plant assemblies, noble-metal furnace sensors, protection-tube builds, surface or tube-skin measurement, wire sensors, miniature probes, multipoint profiling, or plastics tooling sensors.

Harsh Process & Plant

For process installations, furnace environments, and durable field-service assemblies.

MI Cable Thermocouples

Mineral-insulated, metal-sheathed builds for harsh thermal and vibration environments.

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Industrial Head Assemblies

Head-style thermocouple and RTD assemblies for process plants, transmitters, and maintainable field replacement.

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Noble Metal Thermocouples

Type R, S, and B assemblies for furnace, aerospace, and calibration-critical service.

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Protection Tube Thermocouples

Protected high-temperature assemblies for furnaces, kilns, and abrasive processes.

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Surface, Compact & OEM

For tight fit-up, external contact measurement, harnessed builds, and OEM packaging constraints.

Surface Mount Thermocouples

Ring, magnet, and weld-pad styles for pipe, vessel, and equipment surfaces.

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Tube-Skin Thermocouples

Weld-pad and surface-contact probes for heater and furnace skin temperature.

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Wire & Cable Sensors

Extension wire, bare junctions, and lead constructions for custom harnesses.

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Miniature & Needle Probes

Fine-wire and small-OD thermocouple probes for tight spaces, fast response, and compact fixtures.

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Profiling & Multi-Point

For distributed temperature measurement across ducts, vessels, heat-treat work zones, and other multi-zone systems.

Multipoint Thermocouples

Multi-zone assemblies for reactors, vessels, towers, and process profiling.

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Rake Assemblies

Duct, stack, and gas-flow profile measurement with distributed sensing points.

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Spike & Profile Sensors

Thermocouple survey builds plus related profile-sensor applications for qualification and validation work.

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Averaging Sensors

Multi-junction thermocouple and wound-wire RTD averaging assemblies for ducts, plenums, tanks, and distributed measurement zones.

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Duplex / Dual-Element Assemblies

TC/TC, RTD/RTD, and mixed TC/RTD assemblies for redundancy, split instrumentation, and control/alarm separation.

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Application-Specific

For specialized measurement programs tied to particular equipment classes and process geometries.

Gas Turbine Sensors

EGT and TIT thermocouple assemblies with related compressor measurement coverage for turbine systems.

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Nozzle & Melt Thermocouples

Plastics-processing sensors for nozzles, barrels, and molded tooling points.

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Industries Where Specialty Thermocouples Are Common

These industries most often require the broader mix of harsh-duty, profiling, miniature, and specialty thermocouple assemblies shown above.

Aerospace & Defense

Flight-test, engine, cryogenic, and qualification-driven thermocouple programs.

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Metals & Heat Treat

High-temperature furnace, survey, and noble-metal thermocouple applications.

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Energy & Power

Turbine, heater, and severe-duty plant measurement points with elevated thermal demands.

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Request a Thermocouple Quote

Need a specific material, connector, or junction configuration? Start a custom RFQ and our engineers will help specify the best solution.

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Thermocouple Type Chart PDFs and Temperature Tables