Thermocouple extension and compensating cables are typically insulated with the material listed in below table. Below the table you can find a description of the insulation materials.
|PVC HT||PVC High temperature||105°C|
|GS HT||Silicone rubber High temperature||205°C|
|TEX||Glass fiber type E||400°C|
|TEX HT||Glass fiber type R||650°C|
|TEX SHT||Glass fiber quartz||900°C|
PVC stands for Polyvinyl chloride. This type of insulation material is often used for thermocouple extension and compensation cable, especially for compensation grade. the material has been produced for more than 50 years on an industrial scale. PVC is often economically priced and usually has a long life cycle. The material is flame retardant and it can be used in aggressive and chemical environments. The max temperature PVC cables should be used in is 80°C. Kamet also supplies thermocouple compensation cable with PVC HT (high temperature) that can withstand temperatures of 105°C.
Similar material to PVC, XLPE stands for cross-linked Polyethylene. Due to its production process where polymers are cross-linked, the molecular structure of the polymer changes. This results in material where molecules are more tightly bound together, resulting in XLPE to be more heat resistant than PVC. Furthermore, the material does not soften at elevated temperatures. LS0H stands for Low smoke, zero halogen. This means that if a cable is being exposed to high sources of heat, the material does not emit high levels of smoke and no halogen. Max temperature XLPE cables should be used in is 90°C.
Silicone rubber is a common choice for thermocouple extension cables, especially for extension grade and compensation grade. Sillicone rubber thermocouple extension cables have excellent flexibility at both low temperatures and high temperatures. Furthemore, silicone rubber cables have accomplished electrical insulation properties. Silicone rubber thermocouple extension cables can be used for temperatures up to 180°C. the thermocouple extension cables with silicone rubber HT can even be used at temperatures of 205°C.
Hyflon® MFA is a type of PFA (similar to teflon) insulation that is often used for thermocouple extension and compensation cable in all 3 grades: thermocouple grade, extension grade and compensation grade. The material is heat resistant, chemically inert, and has great dielectric properties. The max temperature of MFA is 250°C.
Extruded PFA cables is similar to MFA, but has a slightly different chemical composition, allowing it to withstand even higher temperatures than MFA. Max temperature of PFA is 260°C.
The PTFE thermocouple extension and compensation cables are produced through taping and sintering. The PTFE cables Kamet supplies, can withstand temperatures up to 280°C.
For application in the plastics industry, sometimes thermocouple extension cable is insulated with Kapton® Polyimide tape. Kapton® Polyimide tape is a transparant resistant and amber tape that has superior physical electrical and chemical properties within a broad temperature range. Max temperature the material can be used in is 400°C.
For even higher temperatures, often glass fiber is used as insulation material for thermocouple extension and compensation cable. Usually this type of insulation is either spiralled or braided, and impregnated with varnish. This makes the cables very strong. Furthermore, the material is incombustible.
We distinguish 3 types of glass fiber. The difference between the 3 types is the addition of alumina oxide (Al2O3). Type E glass fiber contains about 14% of alumina oxide (Al2O3), whereas in type R glass fiber this percentage is around 24%. Although type E glass fiber is among the most common type of glass fiber, type R glass fiber can withstand higher temperatures up to 650°C. Quartz glass fiber can even go up to 900°C.
Kamet even supplies cables insulated with ceramic fiber. This material is often used in thermocouple grade. Its’ maximum temperature is around 1200°C, which often exceeds the melting point of the alloy it insulates. When a specific application requires flexible insulation whilst measuring the extreme limits of type K and N thermocouples, ceramic fiber is often used.