Platinum rhodium handle thermocouples, also known as high-temperature resistant precious metal thermocouples, are divided into three types: S-type thermocouples (platinum rhodium 10 platinum thermocouples), R-type thermocouples (platinum rhodium 13 platinum thermocouples), and B-type thermocouples (platinum rhodium 30 platinum rhodium 6 thermocouples). They are mainly divided into single platinum rhodium and double platinum rhodium and are suitable for various high-temperature applications. They are widely used in temperature measurement fields in production processes such as aluminum, metallurgy, glass, ceramics, and industrial salt bath furnaces. Among them, S-type thermocouple is currently the most commonly used type in domestic industry. Due to the high measurement temperature, generally stainless steel protective tubes can only withstand high temperatures up to 1000 degrees. Stainless steel protective tubes that can withstand temperatures above 1000 degrees are expensive, so corundum ceramic protective tubes are commonly used. High purity corundum tubes can withstand high temperatures up to 1600 degrees, and handle type ones are more convenient for use in various industries.