We are having some RTD's at my site.
I am having doubt on immersion and insertion length of thermo well.
U length of thermo well is 280mm and nozzle size projected from pipe is 290mm and pipe id 150mm. What should be minimum "U" length required? and pls tell how to calculate and standard of thermo well designing.

 

It does seem that the nozzle projection is very long. we usually figure on 150 mm from pipe wall. For a small pipe like that I would put the probe in half way.

For larger pipes don't go half way, just 50-75mm or the probe can vortex and eventually snap off.

 

you may find this website helpful for various thermowell installations and designs.

https://www.thermowellsoftware.com/