Calibrating (calibration charts) of thermocouple : chromel - kopel (TCK, Type L). Range of temperatures from - 20 °C to 200 °C
Dependence E.M.F. thermocouple : chromel - kopel from a temperature for a condition, when a free end (shut) of thermocouple is at the zero of degrees celsius.
Chromel - Copel thermocouple (TCC, Type L) have the highest differential sensitivity of all commercially available thermocouples. Chromel-Copel thermocouples are used for more accurate temperature measurements, as well as for measuring small quantities to the temperature difference. Chromel-Copel thermocouples have a very high thermoelectric stability in the range up to 600 ° C. This is explained by the fact that changes in the thermopower hromelevogo and Copel thermoelectrodes cancel each other out, as directed in the same direction. Chromel-Copel thermocouple can operate stably tens of thousands of hours.
The disadvantages include relatively high TCA compared with other thermocouples sensitivity to deformation.
Thermoelectrodes of thermocouple wire chromel and Copel have wide application in temperature measurement in various environments. The devices in which they perform their measurement functions, are used in various control systems. Rugged construction, low cost and high degree of measurement accuracy caused widespread thermocouple from chromel and copely. By design, the thermocouple is a thermoelectric Converter. The principle of Seebeck is the phenomenon whereby a closed electrical circuit consisting of junctions of two metals of different properties, there is a current if the junctions have different temperature. With the direction of the current in this circuit it is possible to determine the sign of the temperature difference between the metal junctions.
The linearity of the temperature sensors of thermocouple and the low inertia allow you to use them in the measurement including high temperatures. Due to the fact that termoelektrodnye wire able for some time to withstand some corrosive environments, thermocouple sensors are used for temperature measurement in kilns firing ceramic factories and other industrial processes.
In the manufacture of termoelektrodny wire thermocouples are used in various alloys. When choosing a thermocouple for a particular purpose is considered the temperature measurement range, measurement accuracy and operating conditions. Thermocouple chromel-Copel is one of the most common and has a wide application in various fields.
In the thermocouple of this type as a positive thermoelectrodes used chromel, and copeley alloy is the negative electrode. Termoelektrodnye wire consisting of a pair of alloys chromel and Copel, operates in the temperature range from -200°C to +600°C. the disadvantages of the thermocouple of this type can be attributed to the sensitivity to deformation. Among the advantages include high measurement accuracy, due to excellent performance coefficients of thermo-EMF of both alloys included in the thermoelectric Converter. In order to fully reveal the properties and characteristics of chromel-Kobeleva the thermocouple, let us consider separately each alloy.
Chromel is an alloy of chromium and Nickel. The combination of these two metals gives excellent thermoelectric properties. Constant thermo-EMF chromel is maintained in the temperature range from +20°C to +1000°C. When operating in the higher temperature properties of the alloy are reduced. This alloy has a melting point of +1435°C. Produced as a wire, chromel has a wide application, and is not only used in thermocouples.
Kopel copper-Nickel alloy, the second component of the chromel-Kobeleva the thermocouple. Physico-mechanical properties Kopel has similarity with the Constantin. But paired with a chromel this alloy shows exceptional properties. In this thermocouple Copel has a maximum electromotive force. The presence in the alloy impurity of iron, carbon, silicon and manganese Kopel provides sufficient heat resistance.