Basics About Thermocouple Types Is Use Today

By Kate McMahon

Modern technological advancements have resulted into development of many thermocouple types to suit various applications. Although there are several types of thermocouples, the working principles are the same across all of them. Basically, this device consists of dissimilar conductors, which make contact and produce a voltage when warmed or heated. The amount of voltage generated depends on the difference in temperature between the metal junction and other components of the circuit.

Thermocouples are among the most broadly used kinds of temperature sensors in use today. They are used to measure, control, and sometimes convert temperature gradients into electrical power. Commercial thermocouples are very cheap and can be interchanged if they malfunction. They are sold with standard connectors and may be used to measure a big range of temperatures. Thermocouples differ from other forms of sensors because they do not need external excitation and they are self-powered.

Certain metal alloys with repeatable and expected relationships between temperature and voltages are applied in the production of these equipment. Different ranges of temperature function best with certain metal alloys. Intermediate connections could be constructed using extension cables if the measurement points are far from the sensors. Cheaper materials may be used to make the extension.

Since there are numerous models of thermocouples, when picking, one should consider the make, insulation, and probe construction. These variables affect range, reliability, and accuracy of readings. The gadgets selected should not confine the ranges of temperature that need to be measured. Key models to select from include type N, B, E, J, S, R, and K. All these makes differ in materials of production, characteristics, and temperature ranges they can sense. Some are applied on specific applications while others are general purpose.

Type K models are low price general purpose gadgets. They are the most utilized and as such, they come in a variety of probes. They may be applied in any application except if stated otherwise. Their sensitivity is around 41 uV per degree Centigrade and are able to measure temperatures within -200 to 1200 degrees Centigrade. Alumel and Chromel metal alloys are utilized in their construction.

Type J sensors are non-magnetic and significantly sensitive. Their sensitivity is stands around 68uV per degree Centigrade. Because of their sensitivity, they are good for utilization on applications that entail low temperatures. Type J are second in popularity after K. Their metal junctions consist of constantan and iron and they can be applied for temperature ranges of between -40 to +750 degrees. Use below +760 degrees Centigrade is not advised.

Type N is designed to be an enhanced type K thermocouple. It is a good choice for high temperature applications. It is a low cost model with the ability to resist high temperature oxidation. As a result of its properties, it is gaining popularity. Types B, S, and R are referred to as noble metal thermocouples, hence they exhibit the same characteristics.

Thermocouple types vary in sensitivity hence their uses. The high stability of type S makes it to be used as a standard for calibration of gold. S model is very costly and has low sensitivity making it unsuitable for use on general applications.

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