Type K (Chromel/Alumel or NiSi)

Type K is the most common thermocouple type. It has a broad operating range up to 1260°C and has good corrosion resistance. Do not use in low Oxygen or reducing atmospheres at higher temperatures. Typically use is above 550°C in Oxygen or Inert atmospheres.

Chemical Composition, %

TypeNiCrSiAl
KP (Chromel)9010
KN973
*KN (Alumel)955

Specification (IEC 60584-1)

TypeEMF Versus Pt.67(mV)
100℃200℃400℃600℃800℃
KP2.826-2.8865.937-6.01712.729-12.82119.532-19.67626.064-26.246
KN1.224-1.2562.140-2.1803.600-3.6445.271-5.3317.080-7.160
KP-KN4.050-4.1878.077-8.19716.329-16.46524.803-25.00733.144-33.46

Physical and Mechanical Properties (RT, Annealed)

TypeDensity, g/cm³Melting Point, ℃Tensile Strength, MPaElongation, %Resistivity, μΩ.m
KP8.51427≥490≥100.71
KN8.61399≥390≥150.30

Features

  • Strong resistance to oxidation than other base metal thermocouples
  • High EMF against Platinum 67
  • Excellent temperature accuracy, sensitivity and stability
  • Low cost

Applications

Type K Thermocouple Alloy is used in many industrial, scientific, and OEM applications.It is recommended for oxidation or inert atmospheres, but can’t be used directly in the following cases:

  • Alternatively oxidizing and reducing atmosphere
  • Atmosphere with sulphur gases
  • Long time in vacuum
  • Low oxidizing atmosphere such as hydrogen and carbon monoxide atmosphere