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Type K Thermocouple provides widest operating temperature range. It consist of positive leg which is non-magnetic and negative leg which is magnetic. In K Type Thermocouple traditional base metal is used due to which it can work at high temperature and can provide widest operating temperature range. One of the constituent metal in K Type Thermocouple is Nickel, which is magnetic in nature.
The characteristic shown by K Type Thermocouple is that they undergo a deviation in output when magnetic material reaches its Curie Point, at around 185°C. K Type thermocouple work very well in oxidizing atmosphere at temperatures up to 1260°C (2300°F) and its tolerance class is ± 1.5 K between -40 and 375°C.
One of the major advantage of K type thermocouple over other thermocouple's is it can function in rugged environmental condition & in various atmospheres.
It has integrated composition of Chromel and Alumel wires has a range of -270 °C to 1260°C and an output of -6.4 to 9 mV over maximum temperature range.
Also known as general purpose thermocouple due to its wide range of temperature.
Type K has a longer life than Type J as in Type J Fe (iron) wire oxidizes rapidly, especially at higher temperature.
They are inexpensive.
Have a fast response.
Small in size and are reliable.
Generally used at temperatures above 540 degrees C.
In K Type Thermocouple positive leg is composed of 90% nickel, 10%chromium and a negative leg is composed of 95% nickel, 2% aluminum, 2% manganese and 1% silicon. These are the most common general purpose thermocouple with a sensitivity of approx 41µV/°C.
To find appropriate range of thermocouple we should use appropriate wire because different wires measure various temperature ranges. Of the four major thermocouple types, type K covers the widest range:-
Thermocouple grade wire, –454 to 2,300F (–270 to1260°C)
Extension wire, 32 to 392F (0 to200°C)
Standard: +/- 2.2°C or +/-.75%
Special Limits of Error: +/- l°C or0.4%
They are mostly used for applications at temperatures above 550 °C up to the maximum working pressure of the thermocouple.
They are used in many industries like Steel & Iron to monitor temperature & chemistry through out the steel making process.
Used for testing temperatures associated with process plants e.g. chemical production and petroleum refineries.
Used for Testing of heating appliance safety.
Type K is commonly used in nuclear applications because of its relative radiation hardness.
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