Thermocouple wire alloys (Types J, T, E and N) TC

spore: profile
id: thermocouple-alloys
spore_version: 0.2
family: resistance-and-thermocouple-alloys
name: Thermocouple wire alloys (Types J, T, E and N)
abbreviation: TC
role: positive and negative legs of base-metal thermocouples
category: metals
type: copper-alloys
summary: |
  A thermocouple is two dissimilar wires joined at a hot junction, and the voltage that appears across the cold ends gives the temperature. This profile covers four standard base-metal pairs. Type J is iron against constantan, Type T is copper against constantan, Type E is chromel against constantan, and Type N is Nicrosil against Nisil. The alloy datasheets read in this run give density, melting point, resistivity, strength and maximum continuous temperature for each leg, and ASTM E230 limits of error for each pair.
best_for: Base-metal temperature sensing where the pair is chosen by range and atmosphere (Type N for stable readings in air above 1000 °C, per Kanthal)
weakest_at: 'Each pair is limited by its atmosphere: the iron leg rusts, sulphur attacks the iron and Nisil legs, and Nicrosil cannot be used in vacuum or reducing gas (Kanthal, Isabellenhutte, Pyromation)'
identity:
  formula: 'Four base-metal pairs, each a positive and a negative leg. Type J: iron (nominal C 0.03, Si 0.05, Mn 0.30 %, Fe balance; Kanthal) against constantan. Type T: copper (Aurubis C10200, 99.95 % minimum Cu; used here as a proxy) against constantan. Type E: chromel (nominal 90 Ni, 10 Cr; Concept Alloys) against constantan. Type N: Nicrosil (Ni balance, Cr 14.2 %, Si 1.5 %; Kanthal) against Nisil (Ni balance, Si 4.3 %, Mg 0.1 %; Kanthal). Constantan: Cu balance with Ni 43.0 to 45.0 %, Mn 0.50 to 2.00 % (Matthey CuNi44Mn1).'
  source: kanthal-nicrosil
  where: Chemical composition table of the Kanthal Nicrosil and Nisil pages; iron composition table of the Kanthal iron page; Concept Alloys chromel nominal composition; Matthey chemical composition table; Aurubis C10200 description
tags:
  environments: []
  stresses:
    - extreme-heat
    - extreme-cold
  applications:
    - thermal-control
properties:
  - benchmark: density
    label: Density, iron leg (Isabellenhutte IRON)
    value: 7.874
    unit: g/cm3
    scope: material
    conditions:
      leg: iron, Type J positive leg
      temperature: +20 °C
    method: Reference value printed in the Isabellenhutte leg datasheet
    status: ground
    source: isabellen-iron
    where: Physical Characteristics (Reference Values), Density at +20 °C, 7.874
  - benchmark: density
    label: Density, iron leg (Kanthal)
    value: 7.86
    unit: g/cm3
    scope: material
    conditions:
      leg: iron, Kanthal thermocouple iron
      temperature: not stated
    method: Value printed in the Kanthal physical properties table
    status: ground
    note: Isabellenhutte prints 7.874 g/cm3 for the same nominal iron leg; both are kept.
    source: kanthal-iron
    where: Physical properties table, Density (g/cm3) 7.86
  - benchmark: melting_point
    label: Melting point, iron leg (Isabellenhutte IRON)
    value: 1496
    unit: °C
    scope: material
    conditions:
      leg: iron, Type J positive leg
      pressure: not stated
    method: Reference value printed in the Isabellenhutte leg datasheet, printed as +1,496 °C
    status: ground
    source: isabellen-iron
    where: Physical Characteristics (Reference Values), Melting point, +1,496
  - benchmark: melting_point
    label: Melting point, iron leg (Kanthal)
    value: 1535
    unit: °C
    scope: material
    conditions:
      leg: iron, Kanthal thermocouple iron
      pressure: not stated
    method: Value printed in the Kanthal physical properties table
    status: ground
    note: The two datasheets disagree by about 39 °C (1535 against 1496). The purity of each product is not stated in the datasheet, so both values are kept.
    source: kanthal-iron
    where: Physical properties table, Melting point (°C) 1535
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C, iron leg (Isabellenhutte IRON)
    value: 81
    unit: W/(m·K)
    scope: material
    conditions:
      leg: iron, Type J positive leg
      temperature: +20 °C
    method: Reference value printed in the Isabellenhutte leg datasheet
    status: ground
    source: isabellen-iron
    where: Physical Characteristics (Reference Values), Thermal conductivity at +20 °C, 81 W/m K
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C, iron leg (Isabellenhutte IRON)
    value: 12
    unit: µΩ·cm
    scope: material
    conditions:
      leg: iron, soft-annealed condition
      temperature: +20 °C
    method: Value printed in the Isabellenhutte electrical values table, printed as µΩ x cm
    status: ground
    source: isabellen-iron
    where: Thermoelectrical and Electrical Values in Soft-Annealed Condition, Electrical resistivity at +20 °C, 12
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, soft annealed iron leg
    value: 370
    unit: MPa
    scope: material
    conditions:
      leg: iron, Type J positive leg
      temper: soft, annealed
      temperature: +20 °C
      dimension: 1.0 mm diameter (datasheet note)
    method: Value printed in the Isabellenhutte mechanical properties table
    status: ground
    source: isabellen-iron
    where: Mechanical Properties at +20 °C in Annealed Condition, soft, tensile strength 370
  - benchmark: elongation
    label: Elongation, soft annealed iron leg
    value: 28
    unit: '%'
    scope: material
    conditions:
      leg: iron, Type J positive leg
      temper: soft, annealed
      temperature: +20 °C
    method: Value printed in the Isabellenhutte mechanical properties table
    status: ground
    source: isabellen-iron
    where: Mechanical Properties at +20 °C in Annealed Condition, soft, elongation 28
  - benchmark: max_service_temp
    label: Recommended maximum continuous temperature, bare iron wire 3.26 mm
    value: 760
    unit: °C
    scope: material
    conditions:
      leg: iron, bare wire
      wire_size: 3.26 mm
      atmosphere: air
    method: Guide value printed in the Kanthal table of recommended maximum continuous operating temperatures
    status: ground
    note: Kanthal prints these as guide values only; bare wire of 0.25 mm falls to 560 °C.
    source: kanthal-iron
    where: Recommended maximum continuous operating temperature, bare wire at 3.26 mm, 760
  - benchmark: cte
    label: Coefficient of thermal expansion, iron leg
    value: 11.7
    unit: 10-6/K
    scope: material
    conditions:
      leg: iron
      temperature: 20 to 100 °C
    method: Value printed in the Kanthal physical properties table
    status: ground
    source: kanthal-iron
    where: Physical properties table, Coefficient of thermal expansion 20 - 100, 11.7
  - benchmark: density
    label: Density, copper leg (Aurubis C10200, proxy)
    value: 8.9
    unit: g/cm3
    scope: material
    conditions:
      leg: copper, Type T positive leg (proxy grade)
      temperature: not stated
    method: Value printed in the Aurubis technical datasheet for C10200
    status: ground
    note: C10200 is commercial oxygen-free copper, not a thermocouple-grade datasheet. It stands in for the Type T copper leg.
    source: aurubis-c10200
    where: Physical properties table, Density [g/cm3] 8.90
  - benchmark: melting_point
    label: Melting point, copper leg (Aurubis C10200, proxy)
    value: 1083
    unit: °C
    scope: material
    conditions:
      leg: copper, Type T positive leg (proxy grade)
      pressure: not stated
    method: Value printed in the Aurubis technical datasheet for C10200
    status: ground
    source: aurubis-c10200
    where: Physical properties table, Melting point [C] 1083
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 20 °C, copper leg (Aurubis C10200, proxy)
    value: 391
    unit: W/(m·K)
    scope: material
    conditions:
      leg: copper, Type T positive leg (proxy grade)
      temperature: 20 °C
    method: Value printed in the Aurubis technical datasheet for C10200
    status: ground
    source: aurubis-c10200
    where: Physical properties table, Thermal cond. at 20 °C [W/mK] 391
  - benchmark: elastic_modulus
    label: Modulus of elasticity, copper leg (Aurubis C10200, proxy)
    value: 117
    unit: GPa
    scope: material
    conditions:
      leg: copper, Type T positive leg (proxy grade)
      temperature: 20 °C
    method: Value printed in the Aurubis technical datasheet for C10200
    status: ground
    source: aurubis-c10200
    where: Physical properties table, Mod. of elasticity at 20 °C [GPa] 117
  - benchmark: yield_strength
    label: Yield strength, soft copper leg (Aurubis C10200, proxy)
    value: 69
    unit: MPa
    scope: material
    conditions:
      leg: copper, soft temper (proxy grade)
      temperature: not stated
    method: Nominal value printed in the Aurubis mechanical properties table
    status: ground
    source: aurubis-c10200
    where: Mechanical properties, Soft, Rp0.2 nominal 69 MPa
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, soft copper leg (Aurubis C10200, proxy)
    value: 179
    value_high: 262
    unit: MPa
    scope: material
    conditions:
      leg: copper, soft temper (proxy grade)
      temperature: not stated
    method: Range printed in the Aurubis mechanical properties table
    status: ground
    source: aurubis-c10200
    where: Mechanical properties, Soft, Rm 179-262 MPa
  - benchmark: cte
    label: Coefficient of thermal expansion at 20 °C, copper leg (Aurubis C10200, proxy)
    value: 17.6
    unit: 10-6/K
    scope: material
    conditions:
      leg: copper, Type T positive leg (proxy grade)
      temperature: 20 °C
    method: Value printed in the Aurubis technical datasheet for C10200
    status: ground
    source: aurubis-c10200
    where: Physical properties table, Coef. of therm exp at 20 °C [10-6/K] 17.6
  - benchmark: density
    label: Density, constantan (CuNi44Mn1, Matthey)
    value: 8.9
    unit: g/cm3
    scope: material
    conditions:
      leg: constantan, negative leg of Types J, T and E
      temperature: not stated
    method: Value printed in the Matthey physical properties table
    status: ground
    source: matthey-cuni44
    where: Physical properties, Density g/cm3 8.9
  - benchmark: melting_point
    label: Melting point range, constantan (CuNi44Mn1, Matthey)
    value: 1230
    value_high: 1290
    unit: °C
    scope: material
    conditions:
      leg: constantan, negative leg of Types J, T and E
      pressure: not stated
    method: Range printed in the Matthey physical properties table
    status: ground
    source: matthey-cuni44
    where: Physical properties, Melting point C 1230-1290
  - benchmark: max_service_temp
    label: Maximum application temperature, constantan (Matthey)
    value: 600
    unit: °C
    scope: material
    conditions:
      leg: constantan, strip and wire
      atmosphere: not stated
    method: Value printed in the Matthey physical properties table and the main properties text
    status: ground
    source: matthey-cuni44
    where: Physical properties, Maximum application temperature 600
  - benchmark: temperature_coefficient_of_resistance
    label: Temperature coefficient of electrical resistance, constantan
    value: -80
    value_high: 40
    unit: 10-6/K
    scope: material
    conditions:
      leg: constantan, CuNi44Mn1
      temperature: 20 to 105 °C
    method: Range printed in the Matthey physical properties table
    status: ground
    note: Non-canonical property name; temperature_coefficient_of_resistance is not in the canonical property file.
    source: matthey-cuni44
    where: Physical properties, Temperature coefficient of electrical resistance (20-105 °°C), -80 to +40
  - benchmark: cte
    label: Linear dilatation coefficient, constantan (Matthey)
    value: 14.5
    unit: 10-6/K
    scope: material
    conditions:
      leg: constantan
      temperature: 20 to 300 °C
    method: Value printed in the Matthey physical properties table
    status: ground
    source: matthey-cuni44
    where: Physical properties, Linear dilatation coefficient (20-300 °°C) 14.5
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, soft annealed constantan strip (R360 temper)
    value: 360
    value_high: 460
    unit: MPa
    scope: material
    conditions:
      leg: constantan, strip, soft annealed (R360, H90)
      temperature: not stated
    method: Range printed in the Matthey mechanical properties table of strips
    status: ground
    source: matthey-cuni44
    where: Mechanical properties of strips, R360 H90 soft annealed, Rm 360-460 N/mm2
  - benchmark: density
    label: Density, chromel-P (Concept Alloys, Type E positive leg)
    value: 8.73
    unit: g/cm3
    scope: material
    conditions:
      leg: chromel-P, nominal 90 Ni and 10 Cr
      temperature: not stated
    method: Value printed in the Concept Alloys typical physical property data
    status: ground
    note: The Concept Alloys sheet is for Chromel-P, labelled ANSI KP. Its use as the Type E positive leg is not confirmed by a Type E source read in this run.
    source: concept-chromel
    where: Typical Physical Property Data, Density (g/cm3) 8.73
  - benchmark: melting_point
    label: Approximate melting point, chromel-P
    value: 1427
    unit: °C
    scope: material
    conditions:
      leg: chromel-P, nominal 90 Ni and 10 Cr
      pressure: not stated
    method: Value printed in the Concept Alloys typical physical property data, given there as 2600 F and 1427 °C
    status: ground
    source: concept-chromel
    where: Typical Physical Property Data, Approximate Melting Point 2600 F (1427 °°C)
  - benchmark: electrical_resistivity
    label: Nominal resistivity at 20 °C, chromel-P
    value: 70.6
    unit: µΩ·cm
    scope: material
    conditions:
      leg: chromel-P, nominal 90 Ni and 10 Cr
      temperature: 20 °C
      unit_in_source: uOhm/cm3
    method: Nominal value printed in the Concept Alloys datasheet; the sheet labels the unit as uOhm/cm3 and it is read as µΩ·cm
    status: ground
    source: concept-chromel
    where: Typical Physical Property Data, Nominal Resistivity (uOhm/cm3) 70.6 at 20 °C
  - benchmark: cte
    label: Coefficient of thermal expansion, chromel-P
    value: 13.1
    unit: 10-6/K
    scope: material
    conditions:
      leg: chromel-P
      temperature: 20 to 100 °C
    method: Value printed in the Concept Alloys datasheet, printed as cm/cm/C E-6
    status: ground
    source: concept-chromel
    where: Typical Physical Property Data, Temp. Coef. Of Expansion (cm/cm/°C) E-6 13.1 (20 to 100 °°C)
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, chromel-P annealed
    value: 95
    unit: ksi
    scope: material
    conditions:
      leg: chromel-P
      temper: annealed
      temperature: not stated
    method: Typical value printed in the Concept Alloys mechanical properties table
    status: ground
    source: concept-chromel
    where: Typical Mechanical Properties, Tensile Strength, annealed (ksi) 95
  - benchmark: yield_strength
    label: Yield strength, chromel-P annealed
    value: 45
    unit: ksi
    scope: material
    conditions:
      leg: chromel-P
      temper: annealed
      temperature: not stated
    method: Typical value printed in the Concept Alloys mechanical properties table
    status: ground
    source: concept-chromel
    where: Typical Mechanical Properties, Yield Strength, annealed (ksi) 45
  - benchmark: density
    label: Density, Nicrosil (Kanthal)
    value: 8.53
    unit: g/cm3
    scope: material
    conditions:
      leg: Nicrosil, positive leg of Type N
      temperature: not stated
    method: Value printed in the Kanthal physical properties table
    status: ground
    note: Isabellenhutte prints 8.50 g/cm3 for its NP Nicrosil; both are kept.
    source: kanthal-nicrosil
    where: Physical properties, Density g/cm3 8.53
  - benchmark: density
    label: Density, Nicrosil NP (Isabellenhutte)
    value: 8.5
    unit: g/cm3
    scope: material
    conditions:
      leg: Nicrosil NP, Cr 14.6 % and Si 1.30 %
      temperature: reference value
    method: Reference value printed in the Isabellenhutte Type N sheet
    status: ground
    source: isabellen-typeN
    where: Physical characteristics row, Melting point / Density, NICROSIL NP 1,394 °C / 8.50 g/cm3
  - benchmark: melting_point
    label: Melting point, Nicrosil (Kanthal)
    value: 1420
    unit: °C
    scope: material
    conditions:
      leg: Nicrosil, positive leg of Type N
      pressure: not stated
    method: Value printed in the Kanthal physical properties table
    status: ground
    note: Isabellenhutte prints 1394 °C for Nicrosil NP; both are kept.
    source: kanthal-nicrosil
    where: Physical properties, Melting point C 1420
  - benchmark: melting_point
    label: Melting point, Nicrosil NP (Isabellenhutte)
    value: 1394
    unit: °C
    scope: material
    conditions:
      leg: Nicrosil NP
      pressure: not stated
    method: Reference value printed in the Isabellenhutte Type N sheet
    status: ground
    source: isabellen-typeN
    where: Melting point / Density row, NICROSIL NP 1,394 °C
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C, Nicrosil (Kanthal)
    value: 1
    unit: Ω·mm2/m
    scope: material
    conditions:
      leg: Nicrosil
      temperature: 20 °C
    method: Value printed in the Kanthal physical properties table
    status: ground
    source: kanthal-nicrosil
    where: Physical properties, Electrical resistivity at 20 °C Ohm mm2/m 1.00
  - benchmark: max_service_temp
    label: Recommended maximum continuous temperature, bare Nicrosil wire 3.26 mm
    value: 1100
    unit: °C
    scope: material
    conditions:
      leg: Nicrosil, bare wire
      wire_size: 3.26 mm
      atmosphere: air
    method: Guide value printed in the Kanthal table of recommended maximum continuous operating temperatures
    status: ground
    note: The same table gives 1250 °C for protected Nicrosil wire of 3.26 mm. Kanthal says the sheet cannot be used in reducing or vacuum atmospheres.
    source: kanthal-nicrosil
    where: Recommended maximum continuous operating temperature, bare wire at 3.26 mm, 1100
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Nicrosil wire 2.0 mm
    value: 800
    unit: MPa
    scope: material
    conditions:
      leg: Nicrosil, wire 2.0 mm
      temperature: not stated
    method: Value printed in the Kanthal mechanical properties table
    status: ground
    source: kanthal-nicrosil
    where: Mechanical properties, wire 2.0 mm, Tensile strength Rm 800
  - benchmark: cte
    label: Coefficient of thermal expansion, Nicrosil
    value: 17
    unit: 10-6/K
    scope: material
    conditions:
      leg: Nicrosil
      temperature: 20 to 100 °C
    method: Value printed in the Kanthal physical properties table
    status: ground
    source: kanthal-nicrosil
    where: Coefficient of thermal expansion, 20 - 100, 17
  - benchmark: density
    label: Density, Nisil (Kanthal)
    value: 8.585
    unit: g/cm3
    scope: material
    conditions:
      leg: Nisil, negative leg of Type N
      temperature: not stated
    method: Value printed in the Kanthal physical properties table
    status: ground
    source: kanthal-nisil
    where: Physical properties, Density g/cm3 8.585
  - benchmark: density
    label: Density, Nisil NN (Isabellenhutte)
    value: 8.55
    unit: g/cm3
    scope: material
    conditions:
      leg: Nisil NN, Si about 4.8 %
      temperature: reference value
    method: Reference value printed in the Isabellenhutte NISIL sheet and the Type N sheet
    status: ground
    source: isabellen-nisil
    where: Physical Characteristics (Reference Values), Density at +20 °C, 8.55
  - benchmark: melting_point
    label: Melting point, Nisil (Kanthal)
    value: 1420
    unit: °C
    scope: material
    conditions:
      leg: Nisil
      pressure: not stated
    method: Value printed in the Kanthal physical properties table
    status: ground
    note: Isabellenhutte prints 1341 °C for Nisil NN, so the two sources differ by 79 °C. Both are kept.
    source: kanthal-nisil
    where: Physical properties, Melting point C 1420
  - benchmark: melting_point
    label: Melting point, Nisil NN (Isabellenhutte)
    value: 1341
    unit: °C
    scope: material
    conditions:
      leg: Nisil NN
      pressure: not stated
    method: Reference value printed in the Isabellenhutte NISIL sheet
    status: ground
    source: isabellen-nisil
    where: Physical Characteristics (Reference Values), Melting point, +1,341
  - benchmark: electrical_resistivity
    label: Electrical resistivity at 20 °C, Nisil NN (Isabellenhutte)
    value: 36
    unit: µΩ·cm
    scope: material
    conditions:
      leg: Nisil NN
      temperature: 20 °C
    method: Value printed in the Isabellenhutte electrical values table, printed as µΩ x cm
    status: ground
    source: isabellen-nisil
    where: Thermoelectrical and Electrical Values, Electrical resistivity at +20 °C, 36
  - benchmark: thermal_conductivity
    label: Thermal conductivity at 100 °C, Nisil (Kanthal)
    value: 27
    unit: W/(m·K)
    scope: material
    conditions:
      leg: Nisil
      temperature: 100 °C
    method: Value printed in the Kanthal physical properties table
    status: ground
    source: kanthal-nisil
    where: Physical properties, Thermal conductivity at 100 °C, 27
  - benchmark: specific_heat
    label: Specific heat at 20 °C, Nisil NN (Isabellenhutte)
    value: 0.5
    unit: J/(g·K)
    scope: material
    conditions:
      leg: Nisil NN
      temperature: 20 °C
    method: Reference value printed in the Isabellenhutte NISIL sheet
    status: ground
    source: isabellen-nisil
    where: Physical Characteristics (Reference Values), Specific heat at +20 °C, 0.50
  - benchmark: ultimate_tensile_strength
    label: Tensile strength, Nisil wire 2.00 mm
    value: 680
    unit: MPa
    scope: material
    conditions:
      leg: Nisil, wire 2.00 mm
      temperature: not stated
    method: Value printed in the Kanthal mechanical properties table
    status: ground
    source: kanthal-nisil
    where: Mechanical properties, wire 2.00 mm, Tensile strength Rm 680
  - benchmark: max_service_temp
    label: Recommended maximum continuous temperature, bare Nisil wire 3.26 mm
    value: 1100
    unit: °C
    scope: material
    conditions:
      leg: Nisil, bare wire
      wire_size: 3.26 mm
      atmosphere: air
    method: Guide value printed in the Kanthal table of recommended maximum continuous operating temperatures
    status: ground
    note: Kanthal says Nisil cannot be exposed to sulphur-containing gases.
    source: kanthal-nisil
    where: Recommended maximum continuous operating temperatures, bare wire at 3.26 mm, 1100
  - benchmark: thermoelectric_emf
    label: Nominal EMF, Nicrosil against Nisil, at 1000 °C
    value: 36.256
    unit: mV
    scope: material
    conditions:
      pair: Nicrosil against Nisil (Type N)
      temperature: 1000 °C
      reference_junction: 0 °C, ITS-90
    method: Nominal EMF value printed in the Kanthal table; the Kanthal sheet lists EMF against Nisil at each temperature
    status: ground
    note: Non-canonical property name; thermoelectric_emf is not in the canonical property file.
    source: kanthal-nicrosil
    where: Thermoelectric properties, Nominal EMF values vs Nisil, 1000 °C, 36.256 mV
  - benchmark: thermoelectric_emf
    label: EMF of Nisil NN against Cu/NIST 175, at 100 °C
    value: -1.763
    unit: mV
    scope: material
    conditions:
      pair: Nisil NN against copper (NIST 175)
      temperature: 100 °C
      reference_junction: 0 °C
    method: Value printed in the Isabellenhutte NISIL sheet
    status: ground
    note: Non-canonical property name; the EMF is against copper, not against the Nicrosil leg.
    source: isabellen-nisil
    where: Thermoelectrical values, EMF versus Cu/NIST 175 at +100 °C, -1.763
  - benchmark: limit_of_error
    label: Limit of error, Type J, standard (ASTM E230)
    value: 2.2
    unit: °C
    scope: material
    conditions:
      pair: Type J, iron against constantan
      temperature_range: 0 to 760 °C
      rule: greater of this value or 0.75 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the ASTM E230 table reproduced by Pelican Wire
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: pelican-tolerances
    where: 'ASTM E230 table, Type J row, Standard column: +/-2.2 or +/-0.75 %'
  - benchmark: limit_of_error
    label: Limit of error, Type J, special (ASTM E230)
    value: 1.1
    unit: °C
    scope: material
    conditions:
      pair: Type J, iron against constantan
      temperature_range: 0 to 760 °C
      rule: greater of this value or 0.4 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the ASTM E230 table reproduced by Pelican Wire
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: pelican-tolerances
    where: 'ASTM E230 table, Type J row, Special column: +/-1.1 or 0.4 %'
  - benchmark: limit_of_error
    label: Limit of error, Type T, standard (ASTM E230)
    value: 1
    unit: °C
    scope: material
    conditions:
      pair: Type T, copper against constantan
      temperature_range: 0 to 370 °C
      rule: greater of this value or 0.75 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the ASTM E230 table reproduced by Pelican Wire
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: pelican-tolerances
    where: 'ASTM E230 table, Type T row, Standard column: +/-1 or +/-0.75 %'
  - benchmark: limit_of_error
    label: Limit of error, Type T, special (ASTM E230)
    value: 0.5
    unit: °C
    scope: material
    conditions:
      pair: Type T, copper against constantan
      temperature_range: 0 to 370 °C
      rule: greater of this value or 0.4 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the ASTM E230 table reproduced by Pelican Wire
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: pelican-tolerances
    where: 'ASTM E230 table, Type T row, Special column: +/-0.5 or +/-0.4 %'
  - benchmark: limit_of_error
    label: Limit of error, Type E, standard (ASTM E230)
    value: 1.7
    unit: °C
    scope: material
    conditions:
      pair: Type E, chromel against constantan
      temperature_range: 0 to 870 °C
      rule: greater of this value or 0.5 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the ASTM E230 table reproduced by Pelican Wire
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: pelican-tolerances
    where: 'ASTM E230 table, Type E row, Standard column: +/-1.7 or +/-0.5 %'
  - benchmark: limit_of_error
    label: Limit of error, Type E, special (ASTM E230)
    value: 1
    unit: °C
    scope: material
    conditions:
      pair: Type E, chromel against constantan
      temperature_range: 0 to 870 °C
      rule: greater of this value or 0.4 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the ASTM E230 table reproduced by Pelican Wire
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: pelican-tolerances
    where: 'ASTM E230 table, Type E row, Special column: +/-1 or +/-0.4 %'
  - benchmark: limit_of_error
    label: Limit of error, Type N, standard (ASTM E230)
    value: 2.2
    unit: °C
    scope: material
    conditions:
      pair: Type N, Nicrosil against Nisil
      temperature_range: 0 to 1260 °C
      rule: greater of this value or 0.75 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the Isabellenhutte Type N sheet, which cites ASTM E230
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: isabellen-typeN
    where: Thermoelectric standard tolerances, TYPE N acc. ASTM E230, Standard +/-2.2 °C or 0.75 % (t90)
  - benchmark: limit_of_error
    label: Limit of error, Type N, special (ASTM E230)
    value: 1.1
    unit: °C
    scope: material
    conditions:
      pair: Type N, Nicrosil against Nisil
      temperature_range: 0 to 1260 °C
      rule: greater of this value or 0.4 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the Isabellenhutte Type N sheet, which cites ASTM E230
    status: ground
    note: Non-canonical property name; limit_of_error is not in the canonical property file.
    source: isabellen-typeN
    where: Thermoelectric standard tolerances, TYPE N acc. ASTM E230, Special +/-1.1 °C or 0.4 % (t90)
  - benchmark: limit_of_error
    label: Limit of error, Type N, Class 1 (IEC 60584)
    value: 1.5
    unit: °C
    scope: material
    conditions:
      pair: Type N, Nicrosil against Nisil
      temperature_range: '-40 to 1000 °C'
      rule: greater of this value or 0.4 % of reading
      reference_junction: 0 °C
    method: Limit of error printed in the Isabellenhutte Type N sheet, which cites IEC 60584
    status: ground
    note: Non-canonical property name. The IEC 60584 classes for Types J, T and E were not read in this run and are not stored.
    source: isabellen-typeN
    where: Thermoelectric standard tolerances, TYPE N acc. IEC 60584, Class 1 +/-1.5 °C or 0.4 % (t90), -40 to 1,000 °C
  - benchmark: max_service_temp
    label: Upper limit of the usable temperature range, Type J pair
    value: 760
    unit: °C
    scope: material
    conditions:
      pair: Type J, iron against constantan
      lower_limit: 0 °C
      atmosphere: vacuum, reducing or inert; oxidising with reduced life
    method: Upper end of the range printed in the Pyromation thermocouple types table, shown as (0 to 760) °C
    status: ground
    note: Upper limit of the pair's Pyromation range, not a single-leg property. The lower limit is in conditions.
    source: pyromation-types
    where: Type J section, Alloy Combination Iron/Constantan, Temp. Range (0 to 760) °C
  - benchmark: max_service_temp
    label: Upper limit of the usable temperature range, Type T pair
    value: 370
    unit: °C
    scope: material
    conditions:
      pair: Type T, copper against constantan
      lower_limit: '-200 °C'
      atmosphere: oxidising, reducing or inert, and vacuum
    method: Upper end of the range printed in the Pyromation thermocouple types table, shown as (-200 to 370) °C
    status: ground
    note: Upper limit of the pair's Pyromation range, not a single-leg property. The lower limit is in conditions.
    source: pyromation-types
    where: Type T section, Alloy Combination Copper/Constantan, Temp. Range (-200 to 370) °C
  - benchmark: max_service_temp
    label: Upper limit of the usable temperature range, Type E pair
    value: 870
    unit: °C
    scope: material
    conditions:
      pair: Type E, chromel against constantan
      lower_limit: 0 °C
      atmosphere: continuously oxidising or inert
    method: Upper end of the range printed in the Pyromation thermocouple types table, shown as (0 to 870) °C
    status: ground
    note: Upper limit of the pair's Pyromation range, not a single-leg property. The lower limit is in conditions.
    source: pyromation-types
    where: Type E section, Alloy Combination Chromel/Constantan, Temp. Range (0 to 870) °C
  - benchmark: max_service_temp
    label: Upper limit of the usable temperature range, Type N pair
    value: 1260
    unit: °C
    scope: material
    conditions:
      pair: Type N, Nicrosil against Nisil
      lower_limit: 0 °C
      atmosphere: air, low oxygen (see Pyromation oxidation note)
    method: Upper end of the range printed in the Pyromation thermocouple types table, shown as (0 to 1260) °C
    status: ground
    note: Upper limit of the pair's Pyromation range, not a single-leg property. The lower limit is in conditions.
    source: pyromation-types
    where: Type N section, Alloy Combination Nicrosil/Nisil, Temp. Range (0 to 1260) °C
corrosion:
  - environment: Moist air or wet storage, iron leg
    headline: Iron rusts readily, and Isabellenhutte says the copper coating does not protect it.
    effect: Isabellenhutte says the iron leg has a strong tendency to corrode and rust, and that it should be stored and used in a dry environment. Its note says the copper coating does not act as a rust protection. Kanthal says iron wire is supplied copper-coated to prevent oxidation. No rust rate or test duration is given.
    rating: severe
    conditions:
      environment: moist air, wet storage
      basis: datasheet statements; no test duration stated
    source: isabellen-iron
    where: Special Remarks on the Alloy; Notes on Treatment
  - environment: Oxidising air above 538 °C, iron leg
    headline: Iron oxidises rapidly above 538 °C, so heavy gauge wire is recommended.
    effect: Pyromation says iron oxidises rapidly above 538 °C and that only heavy gauge wire is recommended for high temperature use. The source gives no oxidation rate.
    rating: severe
    conditions:
      environment: air, above 538 °C
      basis: vendor statement; no test duration stated
    source: pyromation-types
    where: Type J section, oxidation warning sentence
  - environment: Sulphur-bearing atmospheres, iron and Nisil legs
    headline: Iron and Nisil cannot be exposed to sulphur-containing atmospheres.
    effect: Kanthal says iron cannot be exposed to sulphur-containing atmospheres, and that Nisil cannot be exposed to sulphur-containing gases. Pyromation says bare Type J elements should not be exposed to sulphurous atmospheres above 538 °C. The sources give no exposure time or concentration.
    rating: severe
    conditions:
      environment: sulphur-containing gas
      basis: vendor statements; no exposure time stated
    source: kanthal-iron
    where: Special remarks, iron cannot be exposed to sulphur-containing atmospheres; Nisil page, sulphur-containing gases
  - environment: Reducing, vacuum or alternating oxidising and reducing gas, Nicrosil leg
    headline: Nicrosil cannot be used in reducing or vacuum atmospheres.
    effect: Kanthal says Nicrosil cannot be exposed to reducing atmospheres, to alternating oxidising and reducing atmospheres, or to vacuum. The Nicrosil wire is for air use. No time to failure is stated.
    rating: severe
    conditions:
      environment: reducing gas, vacuum, alternating oxidising and reducing gas
      basis: vendor statement; no test duration stated
    source: kanthal-nicrosil
    where: Opening paragraph, cannot be exposed to reducing or alternatively oxidizing and reducing atmospheres or to vacuum
  - environment: Low-oxygen conditions, Type N pair
    headline: Type N has oxidation stability problems and green rot in some conditions.
    effect: Pyromation says Type N can replace Type K where Type K has a shorter life, but notes stability problems from oxidation and the development of green rot. Isabellenhutte says Nicrosil and Nisil show higher oxidation stability than the Type K legs because of their silicon and aluminium balance. No corrosion rate is given.
    rating: moderate
    conditions:
      environment: low oxygen, Type N pair
      basis: vendor statements; no test duration stated
    source: pyromation-types
    where: Type N section, oxidation warning sentence
  - environment: Moist atmosphere, copper and constantan legs
    headline: Type T is not subject to corrosion in moist atmospheres, according to Pyromation.
    effect: Pyromation says Type T thermocouples are not subject to corrosion in moist atmospheres. Matthey gives constantan good corrosion resistance and says it can be welded. No corrosion rate is given for either leg.
    rating: low
    conditions:
      environment: moist atmosphere
      basis: vendor statements; no test duration stated
    source: matthey-cuni44
    where: Main technical properties and features, good corrosion resistance
  - environment: Oxidising or inert air, chromel leg
    headline: Chromel resists oxidation well enough for bare wire to be used across the range.
    effect: Concept Alloys says the superior resistance of the alloys to oxidation allows bare metals to be used throughout the useful range of the Chromel/Alumel pair, from -200 °C to 1260 °C. Pyromation says Type E is recommended for continuously oxidising or inert atmospheres. No corrosion rate is given.
    rating: low
    conditions:
      environment: oxidising or inert air
      basis: vendor statements; no test duration stated
    source: concept-chromel
    where: Opening paragraph, superior resistance of the alloys to oxidation; Pyromation Type E recommended atmospheres
risks:
  hazards:
    - text: 'Airgas nickel wire and rod SDS: GHS Hazard Classification is Not Classified, with no symbol or signal word. The sheet covers a nickel wire and rod product, not a thermocouple pair.'
      ghs: []
      source: airgas-nickel-sds
      where: Section 2, GHS Hazard Classification line
    - text: The same SDS lists manganese, nickel, chromium, chromium oxide, silicon and copper among its ingredients, with exposure limits for several of them.
      ghs: []
      source: airgas-nickel-sds
      where: Section 2 ingredient list and the exposure limits table
  failure_risks:
    - mode: Rust of the iron leg in moist or wet storage
      trigger: Moist air or wet storage of bare or copper-coated iron wire
      consequence: Isabellenhutte says the iron leg has a strong tendency to corrode and rust. The source gives no rate and no effect on calibration.
      severity: high
      source: isabellen-iron
      where: Special Remarks on the Alloy
    - mode: Attack by sulphur on the iron and Nisil legs
      trigger: Exposure of the iron or Nisil leg to sulphur-containing gas
      consequence: Kanthal says the leg cannot be exposed to sulphur-containing gases, and Pyromation says bare Type J elements should not be exposed to sulphurous atmospheres above 538 °C. No failure time is given.
      severity: high
      source: kanthal-iron
      where: Opening statement on sulphur-containing atmospheres
    - mode: Use of Nicrosil in vacuum or reducing gas
      trigger: Vacuum, reducing atmosphere or alternating oxidising and reducing gas
      consequence: Kanthal says the sheet cannot be exposed to these atmospheres. The source gives no failure time.
      severity: high
      source: kanthal-nicrosil
      where: Opening paragraph, cannot be exposed to reducing or alternatively oxidizing and reducing atmospheres or to vacuum
    - mode: Green rot and oxidation of the Type N pair
      trigger: Oxidation and low-oxygen conditions at high temperature
      consequence: Pyromation reports stability problems from oxidation and the development of green rot. No drift value is given.
      severity: moderate
      source: pyromation-types
      where: Type N section, oxidation warning sentence
    - mode: Rapid oxidation of bare iron above 538 °C
      trigger: Bare iron wire in air above 538 °C
      consequence: Pyromation says iron oxidises rapidly above 538 °C and recommends heavy gauge wire. No rate is given.
      severity: moderate
      source: pyromation-types
      where: Type J section, oxidation warning sentence
  side_effects:
    - text: The Airgas SDS says welding fumes can affect the eyes, skin and respiratory system, and lists pancreas and liver effects, from the fume produced when welding nickel-base wire.
      affects: Handling of fume from grinding or welding nickel-containing legs
      source: airgas-nickel-sds
      where: Section 2, Hazards line on welding fumes and gases
  handling:
    - text: Keep the iron leg dry and store it in a dry environment (Isabellenhutte).
      source: isabellen-iron
      where: Special Remarks on the Alloy
    - text: Keep iron and Nisil away from sulphur-containing gas (Kanthal).
      source: kanthal-iron
      where: Opening statement on sulphur-containing atmospheres
    - text: Keep the iron leg above zero degrees C; Kanthal says iron cannot be exposed to temperatures below zero.
      source: kanthal-iron
      where: Opening statement on temperatures below zero
    - text: Keep Nicrosil out of vacuum and reducing gas (Kanthal).
      source: kanthal-nicrosil
      where: Opening paragraph
  mitigations: []
uses:
  - application: thermal-control
    device: Type N thermocouple, Nicrosil and Nisil
    example: Isabellenhutte's Type N sheet lists use in exhaust systems, turbochargers, casts, furnaces and nuclear power stations.
    source: isabellen-typeN
    where: Application notes table
  - application: thermal-control
    device: Type J thermocouple, iron and constantan
    example: Pyromation says Type J suits vacuum, reducing or inert atmospheres, and oxidising atmosphere with reduced life, and that iron oxidises rapidly above 538 °C.
    source: pyromation-types
    where: Type J section, use and atmospheres
  - application: thermal-control
    device: Type T thermocouple, copper and constantan
    example: Pyromation says Type T works in oxidising, reducing or inert atmospheres, and in vacuum, and that it is not subject to corrosion in moist atmospheres.
    source: pyromation-types
    where: Type T section, use and corrosion sentences
supply:
  - subject: Iron
    producers:
      - country: China
        share_percent: 63.8
        year: 2025
      - country: India
        share_percent: 7.5
        year: 2025
      - country: Japan
        share_percent: 4.5
        year: 2025
      - country: Russia
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: false
    recycling: 'USGS iron and steel chapter: recycling is covered in the Iron and Steel Scrap chapter, which is not read in this run.'
    substitutes:
      - 'USGS: iron and steel compete with lighter materials such as aluminum and plastics in the automotive industry.'
    source: usgs-iron-steel
    where: World Production table, pig iron 2025e (world total 1,300 million t, rounded; shares calculated by Space Mushroom against that total); Substitutes; the USGS 2025 list has no iron entry (see usgs-critical-2025)
  - subject: Copper
    producers:
      - country: Chile
        share_percent: 23
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 13.9
        year: 2025
      - country: Peru
        share_percent: 11.7
        year: 2025
      - country: China
        share_percent: 7.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: 'USGS: copper recovered from scrap contributed about 30 % of the U.S. copper supply in 2025.'
    substitutes:
      - 'USGS: aluminum substitutes for copper in radiators, tube, electrical equipment and power cable; titanium and steel are used in heat exchangers.'
    source: usgs-copper
    where: World Mine Production and Reserves table, 2025e (world total 23,000 thousand t, rounded; shares calculated by Space Mushroom against that total); Recycling; Substitutes; the 2025 list adds copper
  - subject: Nickel
    producers:
      - country: Indonesia
        share_percent: 66.7
        year: 2025
      - country: Philippines
        share_percent: 6.9
        year: 2025
      - country: Russia
        share_percent: 5.1
        year: 2025
      - country: Canada
        share_percent: 3.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: 'USGS: most secondary nickel is the nickel content of stainless-steel scrap; nickel recovered from scrap was about 60 % of apparent consumption in 2025.'
    substitutes:
      - 'USGS: low-nickel, duplex or ultrahigh-chromium stainless steels can replace austenitic grades; titanium alloys can substitute for nickel-base alloys in corrosive environments.'
    source: usgs-nickel
    where: World Mine Production and Reserves table, 2025e (world total 3,900,000 t; shares calculated by Space Mushroom against that total); Recycling; Substitutes
  - subject: Chromium
    producers:
      - country: South Africa
        share_percent: 45.1
        year: 2025
      - country: Turkey
        share_percent: 17.6
        year: 2025
      - country: Kazakhstan
        share_percent: 13.7
        year: 2025
      - country: India
        share_percent: 5.9
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: 'USGS: recycled chromium in stainless-steel scrap accounted for 21 % of apparent consumption in 2025.'
    substitutes:
      - 'USGS: chromium has no substitute in stainless steel, the leading end use, or in superalloys.'
    source: usgs-chromium
    where: World Mine Production and Reserves table, 2025e (world total 51,000 thousand t, rounded; shares calculated by Space Mushroom against that total); Recycling; Substitutes
documents:
  - title: 'Kanthal: Nicrosil thermocouple wire datasheet (updated 2024-09-05)'
    type: datasheet
    url: https://www.kanthal.com/en/products/datasheets/material-datasheets/wire/thermocouple-wire/nicrosil/
    year: 2024
  - title: 'Kanthal: Nisil thermocouple wire datasheet (updated 2021-02-04)'
    type: datasheet
    url: https://www.kanthal.com/en/products/datasheets/material-datasheets/wire/thermocouple-wire/nisil/
    year: 2021
  - title: 'Kanthal: thermocouple iron datasheet (updated 2021-02-04)'
    type: datasheet
    url: https://www.kanthal.com/en/products/material-datasheets/wire/thermocouple-wire/thermocouple-iron
  - title: 'Isabellenhutte: NISIL data sheet (issue 17-April-2019)'
    type: datasheet
    url: https://www.isabellenhuette.com/hubfs/Files/Data-sheets/LE/Thermo/NISIL.pdf
    year: 2019
  - title: 'Isabellenhutte: Thermocouples type N / extension leads type NX data sheet (issue 27-March-2020)'
    type: datasheet
    url: https://www.isabellenhuette.com/hubfs/Files/Data-sheets/LE/Thermo/Thermocouples%20type%20N_NX.pdf
    year: 2020
  - title: 'Isabellenhutte: IRON data sheet (issue 30-September-2022)'
    type: datasheet
    url: https://www.isabellenhuette.com/hubfs/Files/Data-sheets/LE/Thermo/IRON.pdf
    year: 2022
  - title: 'Concept Alloys: Chromel-P technical data sheet (Rev. 12-23-09)'
    type: datasheet
    url: https://conceptalloys.com/wp-content/uploads/2013/10/Chromel-PGMVdatasheet091223.pdf
    year: 2009
  - title: 'Matthey: CuNi44Mn1 constantan technical data sheet'
    type: datasheet
    url: https://www.matthey.ch/fileadmin/user_upload/downloads/fichetechnique/EN/CuNi44Mn1_v22E.pdf
  - title: 'Aurubis: Technical datasheet C10200 (Cu-OF)'
    type: datasheet
    url: https://www.aurubis.be/en/dam/jcr:90029b00-b968-486e-bde0-ce56f16022cd/c10200-cu-of-us.pdf
  - title: 'Pelican Wire: Thermocouple tolerances (ASTM E230 table)'
    type: database
    url: https://pelicanwire.com/resources/thermocouple-wire-resources/thermocouple-tolerances/
  - title: 'Pyromation: Thermocouple types'
    type: datasheet
    url: https://www.pyromation.com/products/Thermocouple/Thermocouple-Types.aspx
  - title: 'USGS Mineral Commodity Summaries 2026: Iron and Steel'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Copper'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Nickel'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Chromium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
  - title: 'USGS: About the 2025 List of Critical Minerals'
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
  - title: 'Airgas: Nickel Wire and Rod safety data sheet (approval 2-1-2016)'
    type: sds
    url: https://www.airgas.com/msds/005727.pdf
    year: 2016
gaps:
  - IEC 60584 classes for Types J, T and E are not stored. The Rangdong tolerance chart refused connection in this run, and the search snippets were not used. Only the Type N IEC Class 1 value is stored, from the Isabellenhutte sheet.
  - The iron leg has two melting points (1535 °C from Kanthal and 1496 °C from Isabellenhutte), and two densities (7.86 and 7.874 g/cm3). Both are kept. The purity of each product is not stated, and the Kanthal page says the material is magnetic.
  - Nicrosil and Nisil also differ between Kanthal and Isabellenhutte. Nicrosil density is 8.53 against 8.50 g/cm3, Nicrosil melting point 1420 against 1394 °C, Nisil melting point 1420 against 1341 °C, and the composition is Cr 14.2 against 14.6 % and Si 1.5 against 1.30 %. Every value is kept with its source.
  - The copper leg is a proxy. Aurubis C10200 is commercial oxygen-free copper with 99.95 % minimum Cu, not a thermocouple-grade copper datasheet. A datasheet for the Type T positive leg was not read in this run.
  - The chromel sheet is for Chromel-P, labelled ANSI KP, with nominal 90 Ni and 10 Cr. Its use as the Type E positive leg is not confirmed by a Type E source read in this run.
  - No corrosion rate, oxidation weight gain, drift per hour or test duration was found for any of the four pairs. The corrosion entries are qualitative statements from datasheets and the Pyromation pages.
  - Designations (UNS, EN and DIN codes) are not stored in this file, because a designation belongs to one grade. The constantan leg has UNS C72150 and EN 2.0842 in the Matthey sheet, and they belong in constantan.yaml.
  - The Type J and Type E output in microvolts per degree was not stored, because no datasheet read in this run gives it.
  - The iron Curie or magnetic transition temperatures were not read in a fetched page. Only a search snippet gave 770 °C and 900 °C, so they are not stored.
  - Hazard data rest on one SDS, the Airgas nickel wire and rod sheet, which covers a nickel product. No SDS was read for iron, copper, constantan or chromel thermocouple wire, and PubChem was not read.
  - Supply shares for iron are calculated against the rounded world pig iron total of 1,300 million t, and the USGS iron chapter read here gives pig iron, not iron ore. The EU critical raw materials list was not checked for any of the four metals.
  - Non-canonical benchmark names are used for limit_of_error, thermoelectric_emf and temperature_coefficient_of_resistance. They are listed in the property notes so the import can map them.
sources:
  kanthal-nicrosil:
    title: 'Kanthal: Nicrosil thermocouple wire datasheet'
    url: https://www.kanthal.com/en/products/datasheets/material-datasheets/wire/thermocouple-wire/nicrosil/
    kind: datasheet
    year: 2024
    license: Manufacturer datasheet (cited, not reproduced)
  kanthal-nisil:
    title: 'Kanthal: Nisil thermocouple wire datasheet'
    url: https://www.kanthal.com/en/products/datasheets/material-datasheets/wire/thermocouple-wire/nisil/
    kind: datasheet
    year: 2021
    license: Manufacturer datasheet (cited, not reproduced)
  kanthal-iron:
    title: 'Kanthal: thermocouple iron datasheet'
    url: https://www.kanthal.com/en/products/material-datasheets/wire/thermocouple-wire/thermocouple-iron
    kind: datasheet
    year: 2021
    license: Manufacturer datasheet (cited, not reproduced)
  isabellen-nisil:
    title: 'Isabellenhutte: NISIL data sheet'
    url: https://www.isabellenhuette.com/hubfs/Files/Data-sheets/LE/Thermo/NISIL.pdf
    kind: datasheet
    year: 2019
    license: Manufacturer datasheet (cited, not reproduced)
  isabellen-typeN:
    title: 'Isabellenhutte: Thermocouples type N / extension leads type NX'
    url: https://www.isabellenhuette.com/hubfs/Files/Data-sheets/LE/Thermo/Thermocouples%20type%20N_NX.pdf
    kind: datasheet
    year: 2020
    license: Manufacturer datasheet (cited, not reproduced)
  isabellen-iron:
    title: 'Isabellenhutte: IRON data sheet'
    url: https://www.isabellenhuette.com/hubfs/Files/Data-sheets/LE/Thermo/IRON.pdf
    kind: datasheet
    year: 2022
    license: Manufacturer datasheet (cited, not reproduced)
  concept-chromel:
    title: 'Concept Alloys: Chromel-P technical data sheet'
    url: https://conceptalloys.com/wp-content/uploads/2013/10/Chromel-PGMVdatasheet091223.pdf
    kind: datasheet
    year: 2009
    license: Manufacturer datasheet (cited, not reproduced)
  matthey-cuni44:
    title: 'Matthey: CuNi44Mn1 constantan technical data sheet'
    url: https://www.matthey.ch/fileadmin/user_upload/downloads/fichetechnique/EN/CuNi44Mn1_v22E.pdf
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  aurubis-c10200:
    title: 'Aurubis: Technical datasheet C10200 (Cu-OF)'
    url: https://www.aurubis.be/en/dam/jcr:90029b00-b968-486e-bde0-ce56f16022cd/c10200-cu-of-us.pdf
    kind: datasheet
    license: Manufacturer datasheet (cited, not reproduced)
  pelican-tolerances:
    title: 'Pelican Wire: Thermocouple tolerances'
    url: https://pelicanwire.com/resources/thermocouple-wire-resources/thermocouple-tolerances/
    kind: web
    license: Supplier web page (cited, not reproduced)
  pyromation-types:
    title: 'Pyromation: Thermocouple types'
    url: https://www.pyromation.com/products/Thermocouple/Thermocouple-Types.aspx
    kind: web
    license: Supplier web page (cited, not reproduced)
  usgs-iron-steel:
    title: Mineral Commodity Summaries 2026, Iron and Steel
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-iron-steel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-copper:
    title: Mineral Commodity Summaries 2026, Copper
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-nickel:
    title: Mineral Commodity Summaries 2026, Nickel
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-chromium:
    title: Mineral Commodity Summaries 2026, Chromium
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-critical-2025:
    title: 'USGS: About the 2025 List of Critical Minerals'
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: report
    license: public domain (USGS)
  airgas-nickel-sds:
    title: Safety Data Sheet, Nickel Wire and Rod (Airgas)
    url: https://www.airgas.com/msds/005727.pdf
    year: 2016
    kind: datasheet
    license: Supplier safety data sheet (cited, not reproduced)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 61
  unreachable: 1
  caveats: 5
  note: 'Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable in this run: the Rangdong IEC 60584 tolerance chart (connection refused), so IEC classes for Types J, T and E are not stored, and the Kanthal iron page was read through a fetch tool, not the browser. Caveats: the copper leg is a commercial oxygen-free copper proxy; the iron and Nicrosil/Nisil values disagree between Kanthal and Isabellenhutte, and both are kept; Chromel-P is labelled KP and is used as the Type E positive leg without a Type E source; supply shares are calculated against rounded world totals.'
story:
  risk_groups:
    - title: For people
      lead: The four pairs are alloys of iron, copper, nickel and chromium. The only hazard source read is the Airgas nickel wire and rod SDS, which is Not Classified under GHS.
      level: 1
      verdict: No pair-level hazard classification found
      points:
        - label: Supplier classification
          line: The Airgas nickel wire and rod SDS is classified as Not Classified under GHS and has no signal word. It covers a nickel wire and rod product, not a thermocouple pair.
        - label: Fume
          line: The same SDS lists manganese, nickel, chromium and silicon among its ingredients, so grinding or welding these legs can produce fume with those metals.
    - title: If it fails
      lead: The failure routes in the sources are atmosphere, moisture and temperature. The sources give limits but no failure rates for any pair.
      points:
        - label: Rust
          line: Isabellenhutte says the iron leg has a strong tendency to rust and should be stored dry.
        - label: Sulphur
          line: Kanthal says the iron and Nisil legs cannot be exposed to sulphur-containing gas.
        - label: Vacuum and reducing gas
          line: Kanthal says Nicrosil cannot be used in vacuum or reducing gas.
    - title: Handling and storage
      points:
        - label: Keep iron dry
          line: Store the iron leg in a dry environment, as Isabellenhutte says.
        - label: Keep it above zero
          line: Kanthal says the iron leg cannot be exposed to temperatures below zero.
  why: A thermocouple pair is two dissimilar wires joined at a hot junction, and the voltage across the cold ends gives the temperature. This profile covers four base-metal pairs. Type J uses iron against constantan, Type T uses copper against constantan, Type E uses chromel against constantan, and Type N uses Nicrosil against Nisil. The pairs are chosen by atmosphere more than by range, because the legs fail differently in air, moisture, sulphur and vacuum.
  uses:
    - where: Type N in furnaces and exhaust systems
      line: Isabellenhutte lists Type N use in exhaust systems, turbochargers, casts, furnaces and nuclear power stations.
    - where: Type J in vacuum or reducing gas
      line: Pyromation says Type J suits vacuum, reducing or inert atmospheres, and oxidising atmosphere with reduced life.
    - where: Type T in moist or vacuum service
      line: Pyromation says Type T works in oxidising, reducing or inert atmospheres and in vacuum, and is not subject to corrosion in moist atmospheres.
  can_do:
    - label: Stay within a standard limit
      value: 2.2 °C standard limit for Type J
      benchmark: limit_of_error
      line: Pelican gives the Type J standard limit as 2.2 °C or 0.75 %, over 0 to 760 °C (ASTM E230).
    - label: Hot in air, Type N
      value: 1100 °C bare wire
      benchmark: max_service_temp
      line: Kanthal gives 1100 °C as the guide maximum continuous temperature for 3.26 mm bare Nicrosil and Nisil wire.
    - label: Stable resistance, constantan
      value: '-80 to 40 10-6/K'
      benchmark: temperature_coefficient_of_resistance
      line: Matthey gives constantan a temperature coefficient of electrical resistance of -80 to +40 10-6/K over 20 to 105 °C.
  compare: Compared on the same benchmarks, the copper leg melts at 1083 °C, the constantan leg at 1230 to 1290 °C (Matthey), chromel at 1427 °C (Concept Alloys), and the Nicrosil and Nisil legs at 1420 °C each in the Kanthal sheets. These are leg values, not a ranking of the pairs.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Electrical resistivity
      benchmark: electrical_resistivity
  handling:
    - Keep the iron leg dry and out of sulphur-containing gas (Isabellenhutte and Kanthal).
    - Keep Nicrosil out of vacuum and reducing gas (Kanthal).
    - Keep bare Nicrosil and Nisil wire at or below the guide values in the Kanthal table (1100 °C at 3.26 mm).
  good_for:
    - Type N in air at high temperature, with a guide maximum of 1100 °C for 3.26 mm bare Nicrosil and Nisil wire (Kanthal) and standard limit of error 2.2 °C (ASTM E230).
    - Type T in moist air and in vacuum, with copper and constantan legs (Pyromation).
    - Type E in continuously oxidising or inert atmospheres (Pyromation), with a pair range of 0 to 870 °C.
  watch_out:
    - Iron rusts readily, and the copper coating does not protect it (Isabellenhutte).
    - Iron and Nisil cannot be exposed to sulphur-containing gas (Kanthal).
    - Nicrosil cannot be used in vacuum or reducing gas (Kanthal).
    - The iron melting point differs by 39 °C between Kanthal and Isabellenhutte, and the Nisil melting point differs by 79 °C.
  verdict: The four pairs cover base-metal sensing, and each pair is limited by its atmosphere. Type N suits high temperature in air, Type T suits moist air and low temperature, Type J needs dry and sulphur-free service, and Type E suits oxidising or inert air. The sources give tolerance and range figures, but no corrosion rates or drift data for any pair.
  recipe:
    line: Thermocouple wire is a pair of legs, not one alloy. The four pairs are iron against constantan (Type J), copper against constantan (Type T), chromel against constantan (Type E) and Nicrosil against Nisil (Type N). Constantan is a copper-nickel alloy with manganese (Matthey CuNi44Mn1). Iron, copper and chromel are supplied as wire, and Nicrosil and Nisil as wire, strip or rod (Kanthal, Isabellenhutte).
    parts:
      - name: Iron
        symbol: Fe
        share: balance, with nominal C 0.03 %, Si 0.05 % and Mn 0.30 % (Kanthal)
        role: Positive leg of Type J.
      - name: Copper
        symbol: Cu
        share: balance in constantan (Matthey); 99.95 % minimum in C10200 (Aurubis, used as a proxy)
        role: Positive leg of Type T, and the base of constantan.
      - name: Nickel
        symbol: Ni
        share: 43.0 to 45.0 % in constantan (Matthey); nominal 90 % in chromel (Concept Alloys); balance in Nicrosil and Nisil (Kanthal)
        role: Base of the chromel, Nicrosil and Nisil legs, and the nickel content of constantan.
      - name: Chromium
        symbol: Cr
        share: nominal 10 % in chromel (Concept Alloys); 14.2 % in Nicrosil (Kanthal)
        role: Gives the chromel and Nicrosil legs their high-temperature stability in air.
      - name: Silicon
        symbol: Si
        share: 1.5 % in Nicrosil and 4.3 % in Nisil (Kanthal)
        role: Gives Nicrosil and Nisil their thermoelectric stability and oxidation resistance.
      - name: Manganese
        symbol: Mn
        share: 0.50 to 2.00 % in constantan (Matthey)
        role: Minor addition to constantan, the negative leg of Types J, T and E.