Working principle of platinum rhodium thermocouple

Platinum rhodium thermocouples have the advantages of high accuracy, stability, wide temperature measurement range, long service life, and high temperature measurement upper limit in the thermocouple series. Suitable for oxidizing gases and can also be used in vacuum for a short period of time, but not suitable for reducing gases or environments containing metal or non-metal vapors.

Platinum rhodium thermocouples have the advantages of high measurement accuracy, precise measurement, and high temperature resistance. Among them, B-type platinum rhodium thermocouples can be used for a long time at high temperatures of 1600 degrees Celsius, with the highest temperature measurement reaching 1800 degrees Celsius. S-type platinum rhodium thermocouples can be used for a long time at high temperatures of 1300 degrees Celsius, with the highest operating temperature reaching 1600 degrees Celsius. The difference between B-type and S-type thermocouples lies in the thickness of the platinum rhodium wire, and of course, the cost incurred is also different. They should be selected according to the actual needs of the production site. Platinum rhodium thermocouples can measure the temperature of fluids, steam, gases, and solid surfaces in various industrial production processes. They are widely used in industrial production such as powder metallurgy, vacuum furnaces, smelting furnaces, steelmaking furnaces, industrial salt bath furnaces, and sintering bright furnaces. They are usually used in conjunction with temperature transmitters, regulators, and display instruments to form process control systems, which are used to directly measure or control temperature measurements in various production processes.

Working principle of platinum rhodium thermocouple:
Platinum rhodium thermocouple is composed of two conductors with different compositions connected at both ends to form a circuit. When the temperature of the two junction points is different, a thermal current will be generated in the circuit. 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. The thermoelectric heating of a platinum rhodium thermocouple will increase with the temperature at the measuring end, and its size is only related to the thermocouple material and the temperature at both ends, and is independent of the length and diameter of the thermoelectric electrode. The appearance of various platinum rhodium thermocouples often varies due to actual on-site needs, but their basic structures are roughly the same, usually composed of main components such as hot electrodes, insulation sleeves, protective tubes, and junction boxes.

Selection method:
When the measured temperature is normally between 1000-1300 degrees, it is recommended to use a single platinum rhodium thermocouple (platinum rhodium 10 platinum). When the measured temperature is normally between 1200-1600 degrees, it is recommended to use a dual platinum rhodium thermocouple (platinum rhodium 30 platinum rhodium 6). This ensures the service life of the platinum rhodium thermocouple within the temperature range used.