Things to Remember for Selecting Right Thermocouple Sheath Material for Molten Metal

Thermocouples are a critical insturments in a number of industries where temperature measurement and control are not only a decisive factor but also the safety indicator.  The outer sheath of thermocouples is instrumental in protecting the temperature sensors from external force and damage that are mostly a consequence of corrosion, hustling, anomalous high temperature and erosion. The sheath materials have a wide range of options to choose from: ceramic, titanium, aluminium, copper, versatile range of stainless steel and carbon steel. In thermocouples, this external layer is integrated within a high-density ceramic compound. Sheathed thermocouples can bend to five times the sheath diameter radius.

Industries prefer sheathed thermocouples to unsheathed ones for a wide range of reasons:

• High resistance to shock and vibration: Shock-resistance is imperative to avoid frequent cracks caused by mechanical stresses
• Slow corrosion rate: Sheathed thermocouples are promising in high temperatures for they can work without cracking.
• Flexible: The protective cause assures finer design and conductors. The diameters of these thermocouples can hover around 0.25 mm (0.010″) without any compromise on the structural integrity of the device.

The Essentials of Selecting the Right Sheath:

• Using Stainless Steel Grade Ferric-Chromium Alloy is the best choice as protection sheaths for Molten Alumium
• To improve the product lifespan and prevent faster chemical corrosion by Molten Metal, sheaths with high thermal conductivity are preferred since better heat conduction is obtainable. The sheaths are immune to thermal shock which leads to broken ceramic tubes.
• Striking a balance between response time (thin wall) and life of the sheath (thick wall) 
• While selecting a sheath for base metal thermocouples in type K, N, J, use of High Grade Stainless Sheaths for Molten Non-Ferrous Metals is advised. Refractory Oxide Recrystallized and Impervious Metal are most commonly opted for.

At Eureka Engineering, an ISO 9001-2015 certified company, we provide on-time delivery of quality Metal Sheath Thermocouple assemblies, Ceramic Sheath and Thermowells among other products. 

Our well-stocked inventory of cables and accessories reaches to a wide network of customers spanning across the country.

Know more about our product range at https://www.eurekaengg.com