Classification and advantages and disadvantages of platinum rhodium thermocouples

Classification of Platinum Rhodium Thermocouples:
Platinum rhodium can be divided into single platinum rhodium (platinum rhodium 10 platinum rhodium) and double platinum rhodium (platinum rhodium 30 platinum rhodium 6). As temperature measurement sensors, they are usually used in conjunction with temperature transmitters, regulators, and display instruments to form process control systems. They are used to directly measure or control the temperature of fluids, steam, gas media, and solid surfaces within the range of 0-1800 ℃ in various production processes. The technical specifications of the paper recorder are as follows: temperature measurement range: 0~1800 ℃ 2. temperature measurement accuracy:< ± 0.5% t3, time constant: ≤ 180s4, insulation resistance: 5M Ω (at 20 ℃). Specification and dimensions: 50075010001200 (mm). The diameter of the wire is specified as 0.5mm, with an allowable deviation of -0.015mm.
Advantages: Platinum rhodium thermocouples have high accuracy, good stability, wide temperature measurement range, long service life, and high temperature measurement upper limit in the thermocouple series. Suitable for oxidizing and inert atmospheres, and can also be used in vacuum for a short period of time, but not suitable for reducing atmospheres or atmospheres containing metal or non-metal vapors. A significant advantage of B-type thermocouples is that they do not require compensation wires, as the thermoelectric potential is less than 3 μ V within the range of 0-50 ℃.
Disadvantages: The shortcomings of platinum rhodium thermocouples are thermoelectric potential, low thermoelectric potential, low sensitivity reading, decreased mechanical strength at high temperatures, high sensitivity to pollution, expensive precious metal materials, and therefore large one-time investment. The working principle of high-temperature platinum rhodium thermocouple is that when two conductors with different compositions are connected at both ends to form a circuit, a thermal current will be generated in the circuit when the temperature of the two junction points is different. If there is a temperature difference between the working end and the reference end of the thermocouple, the display instrument will indicate the temperature value corresponding to the thermoelectric potential generated by the thermocouple.