Platinum rhodium thermocouple is also called high temperature thermocouple, precious metals are divided into three types: S type thermocouple (10 - platinum platinum-rhodium thermocouple), R type thermocouple (13 - platinum rhodium platinum thermocouple), B type thermocouple (30 - platinum rhodium platinum rhodium thermocouple), mainly divided into single platinum rhodium and double platinum rhodium, suitable for all kinds of high temperature occasion, are widely used in glass, ceramics and industrial salt bath furnace, etc. The temperature in the process of production.Model S thermocouple is one of the most commonly used thermocouples in the domestic industry.Because the measurement temperature is higher, general stainless steel protection tube high temperature can only be up to 1000 degrees, more than 1000 degrees of stainless steel protection tube is expensive, so Platinum rhodium thermocouple often used corundum ceramic protection tube, high purity corundum tube can withstand high temperature up to 1600 degrees, the disadvantage is fragile.