Commonly used thermocouples can be divided into two categories: standard thermocouples and non-standard thermocouples. The so-called standard thermocouple refers to a thermocouple whose national standard specifies the relationship between its thermoelectric potential and temperature, the allowable error, and a uniform standard index table. It has a display instrument that is compatible with it. Non-standardized thermocouples are not as good as standardized thermocouples in terms of use or order of magnitude. Generally, there is no uniform indexing table, which is mainly used for measurement in some special occasions. Standardized Thermocouples China Since January 1, 1988, thermocouples and thermal resistors have all been produced in accordance with IEC international standards, and seven standardized thermocouples of S, B, E, K, R, J, and T have been designated as China's unified design.
|
Thermocouple type |
Thermocouple material |
|
|
|
Positive |
Negative |
|
S |
Platinum 10 |
Pure platinum |
|
R |
Platinum 13 |
Pure platinum |
|
B |
Platinum 30 |
Platinum 6 |
|
K |
Ni-Cr |
Ni-Si |
|
T |
Cu |
Cu-Ni |
|
J |
Fe |
Cu-Ni |
|
N |
Ni-Cr-Si |
Ni-Si |
|
E |
Ni-Cr |
Cu-Ni |
In theory, any two different conductors (or semiconductors) can be formulated as thermocouples, but as a practical temperature measuring component, its requirements are manifold. In order to ensure the reliability in engineering technology and sufficient measurement accuracy, not all materials can form thermocouples. Generally, the basic requirements for thermocouple electrode materials are:
1. In the temperature measurement range, the thermoelectric properties are stable, do not change with time, have sufficient physical and chemical stability, and are not easily oxidized or corroded;
2. The temperature coefficient of resistance is small, the conductivity is high, and the specific heat is small;
3. The thermoelectric potential generated in the temperature measurement is large, and the linear potential or the linear relationship between the thermoelectric potential and the temperature is a single-valued function relationship;
4. Good material replication, high mechanical strength, simple manufacturing process and low price.
Yangzhou Fongming Cable Factory provides various of thermocouple wire and cable. Welcome to inquire.