This is another area where Thermocouples excel over RTD'S, and it's a simple matter of physics to understand why. Contact temperature sensors do not indicate the temperature of the area around them, they indicate their own temperature along their own sensitive area. In order for any contact temperature sensor to indicate the temperature it is in contact with, the sensor must first come to thermal equilibrium with that environment. Let's not discuss the theoretical aspect that the two never actually attain the same temperature, but just the fact that after some time the two are approximately at thermal equilibrium.
The most basic of Thermocouples is merely a junction of the two dissimilar metal wires. This could be a beaded junction, or a butt-welded junction which turns out to be nearly the same diameter as the Thermocouple wire itself. In order to indicate the surrounding temperature, the junction must be at that temperature. That junction might only be .010" in diameter (for a 30 AWG wire thermocouple), or smaller if finer wires are used. RTD's require either a length of fine Platinum wire wound around or within a former, or a layer of platinum deposited upon a substrate. In all cases, there is an area of Platinum (which is the sensitive portion of the RTD) in contact with this inert, insulating former, and both are physically larger than a weld junction (generally speaking). Both the Platinum and the insulator have thermal mass that must come to equilibrium with the surroundings before the sensor can give an accurate reading. Since there is generally more thermal mass involved here than with the thermocouple junction, the thermocouple will respond faster when put in a similar environment.
The aforementioned statement is true only when reaching for the extremely fast response times of each type and working with bare resistance elements and exposed thermocouple junctions. If both sensors are encapsulated within metal sheaths, and the thermocouple junction is isolated from the sheath (as an RTD circuit always is), then response times will be quite similar.
If your application has to do with temperature measurement, chances are there is information here that is ideal for the application. From rugged industrial thermocouples to precisely accurate RTDs, there is information on temperature sensors for most industry applications
Basically the resistance thermometers is also called RTDs (Resistance Temperature Detectors), and these are sensors used to measure the temperature. If you are looking rtds meters and rtd temperature probes, then please contact us.
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