| There are many industries that utilise temperature | | | | produce a voltage that can be converted into a |
| sensors in day to day operations. Mostly there are | | | | temperature reading. Where the two metals meet is |
| two distinct varieties of contact sensor used for the | | | | called the sensing junction, this junction can be |
| purpose; these are the thermocouple and resistance | | | | connected to extension wires meaning that the |
| temperature detector or RTD. Measurement usually | | | | physical range of the thermocouple is large. Any two |
| takes place in liquids or with contact with the target | | | | metals can be used in the construction of |
| surface. Contact is not however a prerequisite, there | | | | thermocouples making them more affordable than |
| are some temperature sensors out there that | | | | RTD sensors. Thermocouples however can produce |
| operate without contact with the target material; | | | | inaccurate results if other components are introduced |
| instead measuring the ionisation of the air caused by | | | | into the electrical circuit as they rely upon voltage to |
| heat. | | | | measure temperature. |
| When selecting which type of sensor to use there a | | | | As previously stated there are other forms of sensor |
| myriad of considerations that must be made | | | | on the market although the two aforementioned are |
| depending specifically on the application. Additionally | | | | predominant. Increasingly infrared thermometers are |
| however when selecting a sensor it is important to | | | | being used for temperature measurement. These |
| consider the temperature range, the required | | | | work through a non contact method and are |
| accuracy and response time as these will vary with | | | | subsequently used for specific applications that |
| different measuring methods. When accuracy is of | | | | require remote temperature measurement. Usually |
| prime importance an RTD sensor is preferable | | | | they consist of a lens to focus the infrared light on a |
| although for those with an eye on finances, | | | | source and then using the light to take a |
| thermocouples are clearly the cheaper, more | | | | temperature reading. As they do not need contact to |
| affordable option. Hopefully the following break down | | | | measure they are frequently used as a control |
| of the RTD, thermocouple and infrared thermometer | | | | thermometer when calibrating thermostats and inbuilt |
| will help operatives make the decision. | | | | thermometers. As well as this the infrared technology |
| The basics of RTD operation rely on the increase of | | | | is often used in researching the heating and cooling |
| resistivity that occurs when the temperature of a | | | | properties of certain materials. |
| material is increased. Normally RTD sensors are | | | | Hopefully this information has given the uneducated a |
| manufactured from metals such as platinum, nickel | | | | clearer idea of the types of temperature sensor out |
| and copper. Predominantly copper and nickel variants | | | | there on the market today. Depending upon which |
| are used for measuring lower temperatures while | | | | applications they are to be used for, all three have |
| platinum, although more expensive has a wide | | | | various benefits and restrictions. Cost naturally varies |
| temperature range that is useful for a variety of | | | | but in most cases the extra cost is a necessary |
| purposes. Normally RTDs are constructed simply, a | | | | sacrifice to achieve greater levels of accuracy. |
| sensing element is connected a non-conducting | | | | Whether using RTDs, thermocouples or infrared spot |
| element made from ceramic, glass or mica. The | | | | thermometers all can produce valid and accurate |
| element measures the resistance and from this | | | | results; once you have decided which will suit your |
| reading a temperature result is gained. | | | | needs most effectively take time to research the |
| Thermocouples differ from RTDs in that they utilise | | | | models out there to find the perfect solution to your |
| two different metals that are joined at one end to | | | | temperature measurement requirements. |