NiCr-NiSi(Type K) thermocouple finds the widest use in all basemetal thermocouple, at temperature above 500℃。The main chemical composition of positive leg NiCr (KP) are Ni~90% and Cr~10%;
negative leg NiSi (KN) are Ni~97% and Cr~3%. The operating temperature range is -200~1300℃(for short term) and 0~1100℃( for long term)。
Type K thermocouple has strong resistance to oxidation than other base metal thermocouples. It has high EMF against Platinum 67, excellent temperature accuracy, sensitivity and stability, with a low cost. It is recommended for oxidizing or inert atmospheres, but cannot be used directly in the following cases:
(1) Alternatively oxidizing and reducing atmosphere,
(2) Atmosphere with sulphur gases
(3) Long time in vacuum
(4) Low oxidizing atmosphere such as hydrogen and carbon monoxide atmosphere