Temperature Sensors

    A temperature sensors are devices that measure temperature of a medium. As Mike S. mentions in his blog, there are many types of temperature sensors used from simple home purposes to extremely accurate and precise scientific uses. Thermocouples, resistive temperature detectors, infrared thermometers, bimetallic devices, liquid expansion thermometers, and state-of-change devices are the some of the basic types of temperature sensors used for simple or more complex purposes.

    As Mitchell Butler and John Scanlon mention in their blogs, the most basic liquid expansion thermometers, especially mercury thermometers, are the most common temperature sensors that is very easy to use and accessible to everyone. The main elements of the liquid expansion thermometers are the mercury-in-glass sensor which expands and contracts when there is a temperature change and the means of converting this change into a temperature reading. Although accurate, mercury-in-glass thermometers are delicate and mercury is a hazardous material.

    Resistive temperature detectors (RTDs) are the most common sensors used in laboratory and industrial purposes. RTDs use resistors to record resistance values as the temperature changes. They are very accurate and have a wide temperature range which is why they are used for heavy duty purposes. They are preferred over a thermocouple or a thermistor sensor because of their high accuracy and stability for many years.

    Infrared thermometers are non-contact temperature measurement devices that detect the energy emitted by the medium and convert the energy factor into a temperature reading. Infrared thermometers are very useful for temperature measurements of moving objects, or when non-contact measurements are required due to hazardous material; more conventional thermometers do not seem useful in situations like that.

    As mentioned above, temperature sensors are used for multiple purposes. One use of distributed-temperature sensors is to measure the temperature profile of oil reservoirs, which has been done for many years now. The information provided by temperature sensors are very important for the process control of the oil tanks; they provide visual data to optimize the well performance as well as detect flow and viscosity behind the reservoir casing. Nowadays, there are many temperature sensors used in HVAC systems of  buildings in order to efficiently maintain comfortable indoor conditions.


Sources:
http://www.omega.com/prodinfo/temperaturemeasurement.html

http://www.omega.com/Temperature/pdf/RTD_Gen_Specs_Ref.pdf

http://en.wikipedia.org/wiki/Infrared_thermometer

http://www.accessscience.com.ezproxy2.library.drexel.edu/content.aspx?searchStr=Temperature+sensors&id=YB980600