Type K Thermocouple

Chromel / Alumel (Ni-Cr / Ni-Al). The most widely used thermocouple worldwide. Broadest temperature range of all base-metal types. Per ASTM E230 / IEC 60584-1.

ASTM E230IEC 60584-1 Base MetalOxidizing ✓

Tolerance Calculator Type K Products

Temperature Range−200 to +1260°C (−328 to +2300°F)

Extended Range−270 to +1372°C (reduced accuracy)

Positive Conductor (+)Chromel (Ni-10%Cr) — KP

Negative Conductor (−)Alumel (Ni-2%Al-2%Mn-1%Si) — KN

Sensitivity (~25°C)~40.6 µV/°C

ANSI Color (+/−/Overall)Yellow / Red / Yellow

IEC Color (+/−/Overall)Green / White / Green

Type K thermocouple junction construction diagram showing Chromel positive conductor and Alumel negative conductor joined at the hot junction, yellow and red ANSI insulation colors

At-a-Glance Specifications — ASTM E230

Max Temp (continuous)1260°C

Min Temp−200°C

EMF at 1000°C41.276mV

Sensitivity (25°C)40.6µV/°C

Standard Tolerance±2.2°C or ±0.75%

Special Tolerance±1.1°C or ±0.4%

Extension WireKX (Chromel/Alumel)

StandardASTM E230

EMF Reference Table — Type K (ASTM E230)

EMF in millivolts referenced to 0°C cold junction. Selected values at 50°C intervals.

Temp (°C)	EMF (mV)	Temp (°C)	EMF (mV)	Temp (°C)	EMF (mV)
−200	−5.891	200	8.138	700	29.129
−150	−4.913	250	10.153	800	33.275
−100	−3.554	300	12.209	900	37.326
−50	−1.889	400	16.397	1000	41.276
0	0.000	500	20.644	1100	45.119
50	2.023	600	24.905	1200	48.838
100	4.096	650	27.025	1260	51.292

Limits of Error — ASTM E230 / IEC 60584-2

Class	Range	Limit of Error	IEC Equivalent
Standard	0 to +1260°C	±2.2°C or ±0.75% (greater)	Class 2
Special	0 to +1260°C	±1.1°C or ±0.4% (greater)	Class 1
Standard	−200 to 0°C	±2.2°C or ±2.0% (greater)	Class 2

Atmosphere Compatibility

✓ Oxidizing

✓ Inert

✗ Reducing

⚠ Vacuum (limited)

✗ Sulfurous

✗ Moist hydrogen

⚠ 800–1050°C (green rot risk)

✓ Sub-zero / cryogenic

Advantages

Widest temperature range of all base-metal types (−200 to +1260°C)
Most common — universal instrumentation compatibility
Good oxidation resistance in air and oxidizing atmospheres
Cost-effective compared to noble metal types
Available in Special tolerance ±1.1°C or ±0.4%
Non-magnetic above Curie point

Limitations

Green rot: selective Cr oxidation at 800–1050°C in low-oxygen atmospheres
Short-range ordering (SRO) drift below 300°C causes hysteresis
Not suitable for reducing, sulfurous, or carbonizing atmospheres
Alumel (KN) is magnetic below ~160°C — avoid in magnetic field applications
Higher drift rate than Type N at temperatures above 1000°C

Color Code Reference

Standard	Positive (+)	Negative (−)	Overall
ANSI (US)	Yellow	Red	Yellow
IEC 60584	Green	White	Green
BS 1843 (UK)	Brown	Blue	Red

PDF

Type K Thermocouple Datasheet

ASTM E230 · EMF Tables · Tolerance Data · Color Codes

Print Datasheet

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