A detailed introduction to K-type thermocouples

K-type thermocouple, as a temperature sensor, is usually used in conjunction with display instruments, recording instruments, and electronic regulators. It can directly measure the surface temperature of liquid vapor, gas media, and solids in various production processes from 0 ℃ to 1300 ℃.
K-type thermocouples typically consist of main components such as temperature sensing elements, installation fixtures, and junction boxes. It is currently the largest usage of cheap metal thermocouples, with the total usage of other thermocouples. The diameter of K-type thermocouple wire is generally 1.2-4.0mm. The nominal chemical composition of the positive electrode (KP) is Ni: Cr=92:12, and the nominal chemical composition of the negative electrode (KN) is Ni: Si=99:3, with a usage temperature of -200~1300 ℃.
K-type thermocouples have the advantages of good linearity, large thermoelectric electromotive force, high sensitivity, good stability and uniformity, strong antioxidant performance, and low price. They can be widely used in oxidizing inert atmospheres and are widely adopted by users. It cannot be directly used for sulfur, reducing or reducing, oxidizing alternating atmospheres and vacuum at high temperatures, and is not recommended for weak oxidizing atmospheres.
Characteristics of K-type thermocouples
1. Thermocouple is one of the most commonly used temperature detection components in industry. It must be equipped with a secondary instrument, and its advantages are:
① High measurement accuracy. Due to the direct contact between the thermocouple and the measured object, it is not affected by the intermediate medium.
② Wide measurement range. Common thermocouples can measure continuously from -50 to+1600 ℃, while some special thermocouples can measure temperatures as low as -269 ℃ (such as gold iron nickel chromium) and up to+2800 ℃ (such as tungsten rhenium).
③ Simple construction and convenient use. Thermocouples are usually composed of two different types of metal wires, and are not limited by size or beginning. They have a protective sleeve on the outside, making them very convenient to use.
2. Select thermocouples with corresponding graduation numbers based on the temperature measurement range and accuracy
When the operating temperature is between 1300~1800 ℃ and high accuracy is required, B-type thermocouples are generally selected; Low precision is required, and the atmosphere allows for the use of tungsten rhenium thermocouples. Generally, tungsten rhenium thermocouples are used for temperatures above 1800 ℃; The use of temperature between 1000~1300 ℃ requires high accuracy and can be achieved with S-type thermocouples and N-type thermocouples; K-type and N-type thermocouples are generally used below 1000 ℃, and E-type thermocouples are generally used below 400 ℃; At 250 ℃ and negative temperature measurement, T-type thermocouples are generally used. At low temperatures, T-type thermocouples are stable and have high accuracy.