There are various types of thermocouples used in industry to measure temperatures between –200°C to 2300°C. It is important to select the right thermocouple for accurate and efficient temperature measurement. Our Platinum Rhodium sheath thermocouples, available in Type S, R, and B, can withstand continuous temperature monitoring up to 1700°C. Platinum–Rhodium alloy–sheath thermocouples offer superior resistance to extreme heat and a longer service life compared to other sheath materials like Nickel Alloy (Inconel), Nicrobell, and Pyrosil D.TempoTech manufactures these thermocouples in sizes starting from 1.0 mm OD to 4.76 mm OD, with Pt10%Rh and Pt20%Rh sheaths.
How Platinum-Sheathed Thermocouples Are Constructed-Unlike conventional ceramic-insulated noble-metal thermocouples, platinum-sheathed thermocouples are constructed using the thermocouple element wires insulated with high-purity MgO, tightly packed inside the Platinum–Rhodium sheath.
Benefits of using Platinum Sheath Thermocouples
- Extreme Temperature Resistance– Platinum and Rhodium are noble metals with inherent chemical stability and high resistance to tarnishing, corrosion, and oxidation. Their exceptional oxidation resistance at elevated temperatures, along with high conductivity, makes them an excellent choice for extremely high-temperature applications.
- Mechanical Strength:Platinum is one of the most ductile and malleable of all pure metals and can be easily shaped and formed. When alloyed with 10% or 20% Rhodium, the material gains improved mechanical properties, including increased hardness and better tensile strength. Rhodium also helps maintain the structural integrity of Pt10%Rh / Pt20%Rh alloys at 1700°C.
- Flexibility- Compared to conventional noble-metal thermocouples with ceramic sheaths such as alumina, platinum-sheath thermocouples offer greater flexibility during installation. Due to the metal sheath and MgO-packed construction, the thermocouple elements sealed inside the sheath can be formed and bent to fit the desired location within the application.
