Deciphering Thermowell Use In Chemicals


Thermowells are extremely versatile pieces of equipment. They have to be, what with all of the materials into which they are immersed. They serve to protect the heat sensing element of a thermometer, and very often of a thermocouple unit. What is important to recognize is that not all thermowells are created equally. This isn’t to say that each thermowell doesn’t do the job it is supposed to do, but rather that the materials into which you will be immersing your thermowell will affect how well the thermowell works, if at all.

There aren’t many materials a thermowell can’t work with, but before you use the thermowell in a vat of acid, for instance, you want to check to make sure the thermowell is rated for such a task. There are resources for figuring out which thermowell will work in which application, so be sure to consult them before going to work on measuring. For example, there are a multitude of chemicals into which you can immerse a thermowell, and the various chemicals require the use of different metal material out of which the thermowell should be constructed.

For chemical applications stainless steel thermowells work the best, as stainless steel has enough of a chromium content to stop the steel from corroding in the chemical. Hindering corrosion is of course important since the thermowell protects the heat sensing element. If the thermowell gets corroded the heat sensor is jeopardized and more than likely compromised as well. It would be impossible to get an accurate temperature reading in that situation. The chemicals into which you can place a thermowell range the chemical alphabet from acetic acid all the way to zinc sulfate. Most of the chemicals will work well with standard level of 304 stainless steel but of course there are always variations depending on the concentration of the chemical.