Monday, May 5, 2014

The Working Of Resistance Temperature Device

By Tracie Knight


Measurement of temperatures in different environments depends on prevailing circumstances. The use of resistance temperature device or RTD is informed by the principle that temperature affects the resistance of an electric conductor. A known element is used in the correlation to calibrate and standardize the RTDs.

Platinum is a common metal because it displays a constant reaction over a wider range of change in heat. This gives an incredible accuracy level which is important for industrial processes. Temperature sensitivity is likely to affect the results of a production process.

Heat is a vital element in processing and extraction of industrial products. Sensitivity to heat changes and response speed are important in achieving desired results. The metals must be studied carefully alongside the environment where the RTDs will be used. Sending the right information or signal to the control tower ensures that accurate steps are taken. This will prevent compromise on the processes.

Some of the sectors using this technology include automotive, HVAC, control sections and manufacturers of electronic appliances. It also is installed in testing and measuring units for production plants that need to monitor temperatures. The conductor used must be highly sensitive to achieve reliable levels of accuracy. Other metals used as conductors include nickel and copper.

The properties that make an element favorable for this purpose include the heat range and how it responds to fluctuations. Processes such as extraction are sensitive to changes in temperature. Any distortion due to heating or cooling is likely to damage such appliances and compromise their operations.

There are limitations to the use of these devices. They arise out of their behavior when exposed to heat in different circumstances. RTDs are not used where the heat levels go beyond 660 degrees Celsius. Platinum is easily and readily contaminated by impurities at such conditions. These impurities come from the sheath of such thermometers.

Conductors behave different when contaminated by impurities. The impurities alter temperature changes and the trend can be noted at 3 Kelvin or 270 degrees and below. This is attributed to the presence of few phonons. It makes the conductors less sensitive.

The challenges posed by the use of RTDs include accuracy when converting the readings. The relationship between resistance and temperature is a delicate one and easily affected by other conditions. Sensitivity changes depending on heat. This is likely to give erroneous results.

Exposing conductors to continuous heat is likely to alter their properties. This leads to inconsistencies during a thermal cycle. This is defined as hysteresis and threatens to push RTDs out of some operations. It also affects their sensitivity thus limiting their use. The conductors, however, respond well to lower temperatures.

Heat is likely to be lost through the sheath and because of impurities that come into contact with conductors. The presence of foreign current is likely to affect the accuracy of reading given. Use of multiple wires is likely to affect the outcome. Metallic conductors used respond very slowly to changes during heating which is not appropriated for some sensitive operations.




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