In order to select the suitable detector, what materials should be used as sensing elements and wire materials for RTDs?
When talking about RTDs there are three main types, Thin-film elements, Wire-wound elements, and Coiled elements. Thin film elements are made of very thin material, often platinum, on a ceramic substrate. This material is then coated with epoxy or glass this is done to protect the material and add rigidity to the lead wire. With wire wound elements, they are composed of platinum wire coiled around a mandrel composed of insulating material. Lastly, coiled element RTDs are also made of platinum wires but what sets them apart is that it is wires encased in some insulative material. The wires aren’t held firmly inside the material so they are free to expand and contract as needed. The common theme amongst all three types is the use of platinum and ceramics. This isn’t the only option but platinum is a good option because of its repeatable results and wide temperature range.
How are thermocouples types and temperature ranges involved?
Thermocouples have different types based on their different attributes such as durability, chemical resistance, application compatibility, and vibration resistance. Within these categories are material considerations, type R, B, and S thermocouples are made using noble metals (silver, osmium, iridium, platinum, etc.) these metals are used because of their ability to handle high temperatures. Other types of thermocouples such as J, E, and T are made from base metals. This is a matter of price, they aren’t as high performing but they are used a lot more commonly.
Coleman, J. (2021, June 25). Types of Thermocouple: A list of the common types of thermocouple. ISSAA. https://issaa.org/types-of-thermocouple/
What types of RTDs are available? (n.d.). Https://Www.omega.com/En-Us/. https://www.omega.com/en-us/resources/rtd-types