14. What size thermowell is appropriate for my application?

Based on the design of your system you need to know:

  • Operating temperature (°C)
  • Operating pressure (bar), Specific volume (m3/kg)
  • Velocity (m/s)

Once those are established then you’re ready to consult ASME standard PTC 19.3 TW-2010 Thermowell section, which goes through the calculation for the design of the well.  

Here are some basic rules you can follow*:

  • In general, higher flow velocity requires shorter thermowells.
  • Make sure the thermowell material is compatible with the medium in which it is immersed.
  • Economical welded thermowells may be used in low flow applications such as some HVAC chiller lines (typically less than 1-3 ft/sec).
  • Tapered thermowells are typically better suited for high flow velocities than step (reduced-tip) thermowells.

*Because Minco’s products are used in a wide variety of applications, the above information is provided for general consideration purposes only. Consult the expert for your specific application or end use prior to implementing any solution.  Minco assumes no liability for damages resulting from this information provided.

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