Unitech instrumentation manufactures high-temperature sensors with noble metal conductors. These sensors are widely used in glass, ceramic, lime kilns, annealing furnaces, steel industries, power plants, and petrochemical industries. Standard element combinations for thermocouples such as type `r` [pt rh 13%-pt], type `s` [pt rh 1o%-pt], type `b` [pt rh 6%-pt rh 30% or pt 18] and type `c` [tungsten 5%, rhenium/tungsten 26%, rhenium] are available in various element diameters starting from 0.25 to 0.5 mm to suit customer requirement. The temperature ranges are: type `r` [pt rh 13%-pt], type `s` [pt rh l0%-pt] - up to 16oo°c; type `b` [pt rh 6%pt rh 30% or pt 18] is for temperatures up to 1800°c max; and type `c` [tungsten 5% rhenium/tungsten 26% rhenium] for temperatures up to 2300°c max. The standard construction uses high-purity alumina insulators to house the thermocouple element pair followed by protection tube of single or dual ceramic sheaths of various grades depending upon working process temperature and environmental conditions. Type ker 610 - alumina tube with 60%, 80%, 95% a1203; type ker 71u - recrystallised - high alumina tube with 99.5%, 99.9%a1p3 available in 6, 8,10,12,15,20, and 24 mm od. Ceramic outer sheaths are held together with head by holding tubes made of ss 304/ss 316 of 32, 25, and 20 mm diameter.
