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
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TYPE |
Chemical Composition% |
||||
Ni |
Cr |
Mn |
Si |
Al |
|
KP |
90 |
10 |
/ |
/ |
/ |
KN |
97 |
/ |
/ |
3 |
/ |
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TYPE |
EMF Versus Pt.67(mV) |
|||||
100℃ |
200℃ |
400℃ |
600℃ |
800℃ |
||
KP |
2.826~2.886 |
5.937~6.017 |
12.729~12.821 |
19.532~19.676 |
26.064~26.246 |
|
KN |
1.224~1.256 |
2.140~2.180 |
3.600~3.644 |
5.271~5.331 |
7.080~7.160 |
|
KP-KN |
4.050~4.187 |
8.077~8.197 |
16.329~16.465 |
24.803~25.007 |
33.144~33.46 |
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Type |
Density at 20℃ (g/cm³) |
Melting point (℃) |
Tensile Strength(Soft annealed condition in 20℃)(Mpa) |
Elongation(Soft annealed condition in 20℃)(%) |
Resistivity at 20℃ (μΩ.m) |
KP |
8.6 |
1427 |
≥490 |
≥10 |
0.71 |
KN |
8.6 |
1360 |
≥390 |
≥15 |
0.30 |
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