Monday, December 9, 2013

The Ultimate Background Guide To Thermocouple Types

By Tiffany Gill


Thermocouples are temperature-measuring devices which primarily consist of two non-similar conductors. Such conductors interact with each other at several locations within its structure. In the case of coming in contact with any form of matter, a voltage is created when the temperature registered by the area of contact differs from the recognized temperature of reference in other parts of the device system. The voltage created is then typically used for applications like temperature measuring activities, electronic control and production of electricity by taking advantage of temperature gradients. Due to the fact that there are quite a few of them that exist, this article will shed light on the different thermocouple types.

The reason why such devices are very much preferred is due to their low cost to acquire, their assemblies with standard wiring and connectors already, they can operate within a wide spectrum of temperatures, these require no power input to operate, and such devices are not dependent upon external excitation of any form. However, the only significant drawback for the use of thermocouples is its accuracy, making it an unpopular option in precision applications.

The number of different types of these devices are depicted mostly by simple letter nomenclature. Such classifications include the chromel-gold or iron, the platinum kinds, M, C, T, N, J, E and K. Such different versions depend particularly on the used percentage of numerous alloys. Such categories are impacted by factors like stability, output, melting point, chemical properties, availability, convenience and cost. The choice of what among these to use will depend on the innate pros and cons of such devices and their intended application.

The K type is among the most popular, and considered ideal for general purposes. Its cheap and well-known ease of acquiring the probes for its working range make it very ideal for use. The E type, highlighted by its large voltage productivity, makes it an ideal choice in cryogenic uses.

Category J features a more narrow heat sensing range than the K, but has a greater sensitivity than the latter. N categories on the other hand are used in much higher heat applications when compared to the K, but have lower sensitivities. T classifications have very small temperature ranges, but are very sensitive.

The C group may effectively work on a wide range of temperature levels, making it the favored device in vacuum furnaces. A limitation, unfortunately, is that it must not be used over a certain standard temperature when in place in environments with oxygen content.

The M type is used for similar applications as that of the C category, but at a lower maximum operating temperature. The advantage is that it is not limited by the presence of oxygen when it is used. The platinum type on the other hand uses platinum-based alloys and is considered the most stable among all variations. It unfortunately also has the worst sensitivity.

The different variations have their own advantages and disadvantages. Because of this, it is important for a user to be educated about the different thermocouple types. Knowledge is definitely critical in the effective and proper use of these devices.




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