Editing Resistance thermometer (section)

==Advantages and limitations==
The advantages of platinum resistance thermometers include:
* High accuracy
* Low drift
* Wide operating range
* Suitability for precision applications.

'''Limitations:'''

RTDs in industrial applications are rarely used above 660&nbsp;°C. At temperatures above 660&nbsp;°C it becomes increasingly difficult to prevent the platinum from becoming contaminated by impurities from the metal sheath of the thermometer. This is why laboratory standard thermometers replace the metal sheath with a glass construction. At very low temperatures, say below −270&nbsp;°C (3&nbsp;K), because there are very few [[phonon]]s, the resistance of an RTD is mainly determined by [[impurities]] and [[boundary scattering]] and thus basically independent of temperature. As a result, the [[Sensitivity (electronics)|sensitivity]] of the RTD is essentially zero and therefore not useful. {{citation needed|date=September 2014}}

Compared to [[thermistor]]s, platinum RTDs are less sensitive to small temperature changes and have a slower response time. However, thermistors have a smaller temperature range and stability.

===RTDs vs thermocouples===
The two most common ways of measuring temperatures for industrial applications are with resistance temperature detectors (RTDs) and [[thermocouple]]s. The choice between them is typically determined by four factors.
;Temperature: If process temperatures are between {{convert|-200|and|500|C|F}}, an industrial RTD is the preferred option. Thermocouples have a range of {{convert|-180|to|2320|C|F}},<ref>{{Cite web|url=http://www.omega.com/temperature/Z/pdf/z241-245.pdf|title=Omega Engineering &#124; Shop for Sensing, Monitoring and Control Solutions with Technical Expertise}}</ref> so for temperatures above {{convert|500|C|F}} it is the contact temperature measurement device commonly found in physics laboratories.
;Response time: If the process requires a very fast response to temperature changes (fractions of a second as opposed to seconds), then a thermocouple is the best choice. Time response is measured by immersing the sensor in water moving at {{cvt|1|m/s}} with a 63.2% step change.
;Size: A standard RTD sheath is {{convert|3.175|to|6.35|mm|in|abbr=on}} in diameter; sheath diameters for thermocouples can be less than {{convert|1.6|mm|in|abbr=on}}.
;Accuracy and stability requirements: If a tolerance of 2&nbsp;°C is acceptable and the highest level of repeatability is not required, a thermocouple will serve. RTDs are capable of higher accuracy and can maintain stability for many years, while thermocouples can drift within the first few hours of use.