There are several types of thermocouple wires, each identified by a letter designation. The most common types of thermocouple wires are:
Type K: Chromel/Alumel - One of the most popular and widely used thermocouple types. It has a wide temperature range and good accuracy. It is commonly used in various industries.
Type J: Iron/Constantan - Suitable for general-purpose applications in the range of -210°C to 1200°C. It has a lower cost compared to Type K.
Type T: Copper/Constantan - Known for good accuracy and stability at low temperatures. It is often used in cryogenic applications.
Type E: Chromel/Constantan - Suitable for applications with a temperature range of -270°C to 1000°C. It has high accuracy and is commonly used in food industry applications.
Type N: Nicrosil/Nisil - Offers good accuracy and stability, especially at high temperatures. It is commonly used in aerospace and nuclear applications.
Type S: Platinum/Rhodium - Known for high accuracy and stability at high temperatures, up to 1600°C. It is often used in the pharmaceutical and chemical industries.
Type R: Platinum/Rhodium - Similar to Type S but with a slightly different temperature range, up to 1600°C. It is commonly used in high-temperature applications.
Type B: Platinum/Rhodium - Offers excellent accuracy and stability at very high temperatures, up to 1700°C. It is typically used in high-temperature applications in industrial settings.
Each type of thermocouple wire has its own unique characteristics, temperature range, and applications where it is most suitable. The selection of the appropriate type of thermocouple wire depends on factors such as the temperature range of the application, accuracy requirements, environmental conditions, and cost considerations.
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).
These two alloys have different thermoelectric properties at different temperatures, which can generate a thermoelectric potential difference for temperature measurement. The working temperature range of K-type thermocouple wires is usually between 0 ° C and 1200 ° C, and it is one of the commonly used temperature sensors in many industrial and laboratory applications.
They have good linear characteristics and relatively high accuracy, and their stability at high temperatures is relatively good, so they are widely used in some high-temperature environments.
The connectors of K-type thermocouple wires often use standard K-type plugs, allowing them to be connected to various temperature measuring devices, control systems, recorders, etc., facilitating temperature measurement and data acquisition. Due to the reliability and applicability of K-type thermocouple wires, they are widely used in various industries such as metallurgy, petrochemicals, energy production, and food processing
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 |