A Unembellished Handbook For Thermocouple Types And Possible Utilization In Everyday Equipment
Simply put a TC is a type of sensor that measures temperature and temperature differences. They are based on the principle that when two dissimilar metals are joined together there is a proportional amount of voltage that is produced. The Voltage is directly related to the temperature difference of the two metals the TC is composed of. Using this idea, there are several different kinds of TCs depending on their uses.
Type K is made from chromel and alumel. It is considered as the all purpose general use unit. It has a relative low cost for construction and its use can be found in many different kinds of probes. It has a sensitivity from -200 degrees C to +1200 degrees C.
Type E is constructed from constantan and chromel. Looking at the higher than average output they are generally only used for cold temperature applications. It is also used for non magnetic applications. Its counter is the type B made from constructed from rhodium and platinum. Because the output voltage curve is high they are used for temperatures ranging around 1800 degrees C.
Type N is constructed from nisil and nicrosil. It is notable for its higher stability and fantastic resistance for high temperature oxidation. Due to it not being made using platinum it has a production cost that is much lower and is often a unit of choice for most high temperature applications today. It was built as a replacement for all types K TCs and is used for everyday applications more and more.
The type R and the type S are both constructed with rhodium and platinum. Because they use platinum for constructing them they have a production cost that is higher than average. The type R's are used for temperatures of 1600 deg C. The S's are used for temperatures of 1600 deg also. The typical use for a type S is in melting gold, where the melting point is around 1064 deg C.
Type J's are made using iron and constantan. It has quite a limited temperature range at -40 deg C to 750 degrees C. This limited operational range makes it much less popular as apposed to more often used type Ks. The main use it has is for older vintage type equipment which can not use the more modern TCs.
This is a basic look at the more common of the thermocouple types and the things they are used for. Even though it seems their name makes them sound very complex or rare, nothing could possibly be further from the truth. When you take a nice hot shower just relax, your water heater's thermocouple has been working quietly to keep the water hot every hour of every day.
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