K-type thermocouple wire is a common type of thermocouple composed of two different metal alloys: nickel/silicon alloy (usually referred to as KN or KNX) and nickel/chromium alloy (usually referred to as KP or KPX).
Advantages:
Good antioxidant and stability
Antioxidant environment:
Nickel chromium alloy has excellent stability in oxidizing atmospheres (such as air) and is suitable for high-temperature oxidation environments such as boilers and heat treatment furnaces.
Corrosion resistance:
It performs better than J-type (iron is prone to corrosion) or E-type (nickel chromium constantan) in weakly acidic and alkaline environments.
What differentiates one thermocouple from another is the metals in its two wires: the positive leg and the negative leg. Because each thermocouple type has a different pairing, they differ in temperature limits, process conditions (inert, oxidizing, reducing atmospheres, heavy vibration), and so on.
Conductor Name |
Thermocouple Type | Grade |
Temperature range ℃ | Allowable Tolerance /℃ |
PtRh30-PtRh6 | B | Ⅱ | 600~1700 | ±0.25% t |
Ⅲ | 600~800 | ±4 | ||
800~1700 | ±0.5%t | |||
PtRh13-Pt | R | Ⅰ | 0~1100 | ±1 |
1100~1600 | ±[1+(t-1100) ×0.3%] | |||
Ⅱ | 0~600 | ±1.5 | ||
600~1600 | ±0.25% t | |||
PtRh10-Pt | S |
Ⅰ | 0~1100 | ±1 |
1100~1600 | ±[1+(t-1100) ×0.3%] | |||
Ⅱ | 0~600 | ±1.5 | ||
600~1600 | ±0.25% t | |||
NiCr-Ni | K | Ⅰ | -40~1100 | ±1.5℃ or ±0.4%t |
Ⅱ | -40~1300 | ±2.5℃ or ±0.75%t | ||
Ⅲ | -200~40 | ±2.5℃ or ±1.5%t | ||
NiCrSi-NiSi | N | Ⅰ | -40~1100 | ±1.5℃ or ±0.4%t |
Ⅱ | -40~1300 | ±2.5℃ or ±0.75%t | ||
Ⅲ | -200~40 | ±2.5℃ or ±1.5%t | ||
NiCr-CuNi (Constantan) | E | Ⅰ | -40~1100 | ±1.5℃ or ±0.4%t |
Ⅱ | -40~1300 | ±2.5℃ or ±0.75%t | ||
Ⅲ | -200~40 | ±2.5℃ or ±1.5%t | ||
Fe-CuNi (Constantan) | J | Ⅰ | -40~750 | ±1.5℃ or ±0.4%t |
Ⅱ | -40~750 | ±2.5℃ or ±0.75%t | ||
Cu-CuNi (Constantan) | T | Ⅰ | -40~350 | ±0.5℃ or ±0.4%t |
Ⅱ | -40~350 | ±1.0℃ or ±0.75%t | ||
Ⅲ | -200~40 | ±1.0℃ or ±1.5%t |