K-type thermocouple is a widely used temperature sensor that measures the temperature of an object based on the principle of thermoelectric effect. It usually consists of main components such as temperature sensing elements, installation and fixing devices, and junction boxes. The nominal chemical composition of the positive electrode (KP) of K-type thermocouple is Ni=90:10, and the nominal chemical composition of the negative electrode (KN) is Ni=97:3. Its operating temperature range is -200 ℃ to 1300 ℃, and in some cases, it can even reach 1350 ℃ for a short period of time.
Introduction to K-type thermocouple products
K-type thermocouple is a widely used temperature sensor that measures the temperature of an object based on the principle of thermoelectric effect. It usually consists of main components such as temperature sensing elements, installation and fixing devices, and junction boxes. The nominal chemical composition of the positive electrode (KP) of K-type thermocouple is Ni=90:10, and the nominal chemical composition of the negative electrode (KN) is Ni=97:3. Its operating temperature range is -200 ℃ to 1300 ℃, and in some cases, it can even reach 1350 ℃ for a short period of time.
The main features of K-type thermocouples include:
High temperature stability: K-type thermocouple is a type of high-temperature and inexpensive metal thermocouple, which is inexpensive and widely used. Its annual output accounts for almost half of all metal thermocouples. Its thermoelectric potential is approximately linearly related to temperature, with a high thermoelectric potential, high thermoelectric potential rate, and good oxidation resistance. It can be used for a long time in oxidizing atmospheres and air.
Wide applicability: K-type thermocouples are widely used in various industrial applications, such as power, chemical, aerospace, pharmaceutical and other fields, to measure the temperature of various substances under high and low temperature conditions. It can directly measure the surface temperature of liquid vapor and gas media, as well as solids, ranging from 0 ℃ to 1300 ℃.
Good reproducibility: K-type thermocouples have a stable relationship between thermoelectric potential and temperature, with good reproducibility, making temperature measurement results accurate and reliable.
However, K-type thermocouples also have some limitations. For example, it is prone to magnetic transformation within 150-200 ℃, and the thermoelectric potential may undergo non-standard changes with the heating program within the range of 250-550 ℃. In addition, K-type thermocouples are not suitable for use in vacuum, carbon containing, and sulfur-containing atmospheres because when the oxygen partial pressure is low, chromium in the nickel chromium electrode will preferentially oxidize, resulting in a significant change in thermoelectric potential.
When using K-type thermocouples, the corresponding thermocouple type can be selected based on the temperature measurement range and accuracy requirements. For example, for situations where the operating temperature is between 1300~1800 ℃ and high accuracy is required, B-type thermocouples are generally used; Below 1000 ℃, K-type thermocouples or N-type thermocouples are generally used.
In addition, the welding method of K-type thermocouples is also an important factor affecting their performance. Common welding methods include argon arc welding, carbon powder welding, gas welding, salt water welding, and arc welding. These welding methods each have their own advantages and disadvantages, and it is necessary to choose the appropriate welding method according to the actual situation.
Overall, K-type thermocouples have become indispensable temperature measurement devices in industries, aerospace, chemistry, and other fields due to their high temperature stability, wide applicability, and good reproducibility.
