Well thermometers work in environments that are quite extreme. They are typically placed into a piping system or tank that has a fliud under high pressure, high temperature, or is corrosive. The probe of the thermometer is coated with a heat conductive compound when it goes into the well. The fuild being measured passes its heat on to the well and is conducted to the probe of the thermometer. The probe may be made of Inconel (tm) for a number of different reasons. First, the probe may not be in a well and will have to survive the enviroment that it has been placed in. Second, even though it is in a well, at some point in its life, the well may eroded or crack and allow the fluid being measured to touch the probe. In this case the probe being made of Inconel (tm) is important because; 1. Again the probe is in direct contact with the fluid. 2. If the probe was made of something other than Inconel (tm), there would be a high chance for galvanic corrosion. Galvanic corrosion occurs when two metals of dissimiliar electronegativities come into contact through a medium that conducts electricity, and oxygen is present. These three things required for galvanic corrosion are all readily available in a typical situation where a well thermometer would be used. To eliminate one of them, the probe is made of the same material as the piping. In this case Inconel (tm).

Well thermometers come in many different shapes and sizes.