Thermocouples are widely used across a number of industries and in commercial air and gas applications to measure temperatures. Custom resistance temperature Detectors or RTDs as they are also known, provide a better alternative to Thermocouples when high accuracy measurements of temperatures are required. RTDs are sensors that measure temperature, functioning on the norm that the electrical resistance of a material changes with a change in temperatures. The material of the RTD being known, they provide for high precision measurements of temperatures.
Consisting of temperature sensors, RTDs work on the basis that the current resistance of a material will change with a change in temperatures. As the change in resistance for known materials can very easily be predicted, this correlation is used to perform highly accurate measurements of temperature.
Not only higher efficiency, RTDs also provide better repeatability and are slowly rendering thermocouples obsolete especially in any application below 600 degrees Celsius. RTDs are also manufactured in a number of form factors and are also more stable. However, if any process requires a fast response time, thermocouples are preferred. Thermocouples are also used at temperatures above 660 degrees Celsius, wherein the element of RTDs tends to get contaminated and at temperatures below 270 degrees Celsius whence the sensitivity of the RTD drops to zero. Also, thermocouples are smaller in size as compared to RTDs and are used in size critical applications.
The most common types of RTDs are based on the features that may be a thin film, coil, or wire wound type. Some other types of RTDs include carbon resistor elements and strain free custom shaped elements.
However, in case of critical applications involving quick response time, thermocouples are ideal. Thermocouples are also used when the temperatures are not appropriate for RTDs, that is, above 660 degrees Celsius. At these high temperatures, elements of RTDs incline to get contaminated. Also at temperatures below 270 degrees Celsius, the sensitivity of the element drops down to zero. Thermocouples are smaller in size as likened to RTDs and are also used in applications where size can prove to be a concern.
Commonly classified on the basis of the structure of the elements, RTDs are broadly classified into wire wound, coil, or thin film types. Another type of RTD has carbon resistor elements. RTDs are usually provided by manufacturers in custom shaped, strain free forms. RTDs are also available in different shapes corresponding to various applications in which they are to be used. The element material used is platinum, in case the range of temperatures to be measured is high and is otherwise the nickel in the case of higher precision measurements over lower temperatures distribution.
Most manufacturers are also the designers and assemblers of all the components of RTDs. That is why manufacturers have come to offer customized modules which not only prove to be lower in cost, but also efficiently fulfill various client demands. RTDs also come with accessories for connections and additional mounting hardware and enclosures.
Thermocouples, although having been extensively used for temperatures sensing applications across industries, have their limitations. Resistance Temperature Detectors provide for higher precision and a better repeatability for similar applications. RTDs, however, only working over a given temperature range and are fragile, but are nonetheless, the device of choice for some industries and many applications and may soon replace thermocouples altogether.
Consisting of temperature sensors, RTDs work on the basis that the current resistance of a material will change with a change in temperatures. As the change in resistance for known materials can very easily be predicted, this correlation is used to perform highly accurate measurements of temperature.
Not only higher efficiency, RTDs also provide better repeatability and are slowly rendering thermocouples obsolete especially in any application below 600 degrees Celsius. RTDs are also manufactured in a number of form factors and are also more stable. However, if any process requires a fast response time, thermocouples are preferred. Thermocouples are also used at temperatures above 660 degrees Celsius, wherein the element of RTDs tends to get contaminated and at temperatures below 270 degrees Celsius whence the sensitivity of the RTD drops to zero. Also, thermocouples are smaller in size as compared to RTDs and are used in size critical applications.
The most common types of RTDs are based on the features that may be a thin film, coil, or wire wound type. Some other types of RTDs include carbon resistor elements and strain free custom shaped elements.
However, in case of critical applications involving quick response time, thermocouples are ideal. Thermocouples are also used when the temperatures are not appropriate for RTDs, that is, above 660 degrees Celsius. At these high temperatures, elements of RTDs incline to get contaminated. Also at temperatures below 270 degrees Celsius, the sensitivity of the element drops down to zero. Thermocouples are smaller in size as likened to RTDs and are also used in applications where size can prove to be a concern.
Commonly classified on the basis of the structure of the elements, RTDs are broadly classified into wire wound, coil, or thin film types. Another type of RTD has carbon resistor elements. RTDs are usually provided by manufacturers in custom shaped, strain free forms. RTDs are also available in different shapes corresponding to various applications in which they are to be used. The element material used is platinum, in case the range of temperatures to be measured is high and is otherwise the nickel in the case of higher precision measurements over lower temperatures distribution.
Most manufacturers are also the designers and assemblers of all the components of RTDs. That is why manufacturers have come to offer customized modules which not only prove to be lower in cost, but also efficiently fulfill various client demands. RTDs also come with accessories for connections and additional mounting hardware and enclosures.
Thermocouples, although having been extensively used for temperatures sensing applications across industries, have their limitations. Resistance Temperature Detectors provide for higher precision and a better repeatability for similar applications. RTDs, however, only working over a given temperature range and are fragile, but are nonetheless, the device of choice for some industries and many applications and may soon replace thermocouples altogether.
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