Accurately Measure Process Temperature without a Thermowell or Process Penetration using Rosemount X-well Technology

temperature-surface-sensorUpdate: Download the whitepaper, Achieve Accurate Process Temperature Measurement with Surface Sensor Innovation for more on the Rosemount X-well technology.

Original post: In an earlier post, Online Calculation Tool for Thermowell Installations, we shared ways to avoid resonant frequencies caused by fluid flow around a thermowell inside of process piping.

But what if you could eliminate the need for the thermowell entirely?

Emerson's Ryan Leino


I caught up with Emerson’s Ryan Leino who shared Rosemount X-well™ technology, which provides an accurate, repeatable, extrapolated process temperature measurement from a surface measurement. Just imagine being able to measure process temperature with no more leak points, no more process shutdowns due to maintaining thermowells, reduced design complexity which includes wake frequency calculations (WFCs) and more flexibility as project changes occur.

Traditional thermowell installations introduce design complexity, installation expense and require ongoing maintenance. The required pipe penetration introduces a potential leak point and the thermowell is subject to corrosion, abrasion and bending stresses by the fluid flowing around it.

Traditional surface sensors are one way you can go to avoid complexity and design issues associated with thermowells. However, this method gives you the temperature of the surface you are measuring, a value that does not provide an accurate or repeatable representation of an in-pipe process temperature.

The new Rosemount X-well technology removes the challenges of a thermowell assembly while providing a process temperature measurement that a standard surface sensor cannot.

Rosemount-X-well-graph

From the chart, note the green Rosemount X-well line and how closely it tracks the process temperature as ambient temperature changes, especially in relation to the yellow surface temperature. The temperature of the process fluid is measured without the need for a process penetration or thermowell.

This process temperature is calculated via a Rosemount X-well thermal conductivity algorithm in the Rosemount 648 wireless temperature transmitter and Rosemount 0085 pipe clamp and sensor assembly.

Rosemount X-well technology works by measuring the ambient and pipe surface temperatures. These values combined with an understanding of the temperature measurement assembly’s thermal conductivity properties and information of the process pipe material and schedule provide the input for the calculations and extrapolations of the process fluid temperature inside the pipe.

Ryan explained that Rosemount X-well accuracy is a function of ambient and process temperature differential. He shared several scenarios with me where the ambient temperature and the fluid inside the pipe were at various values. When process and ambient temperatures are similar, Rosemount X-well accuracy is approximately that of a traditional thermowell assembly.

As process and ambient temperature diverge, Rosemount X-well accuracy becomes slightly less than that of traditional thermowell accuracy with a total probable error (TPE) less than 1.2% of process temperature reading at its most inaccurate level. Some good applications for the Rosemount X-well technology include:

Rosemount-X-well-assembly

  • Pipeline monitoring
  • Retrofit existing pipes that need new measurement points
  • Pipelines requiring frequent cleaning
  • High velocities
  • Slurries and heavy particulate fluids
  • Clean-In-Place (CIP) processes
  • High viscosity fluids
  • Harsh processes requiring exotic materials
  • Wellhead monitoring

And, unless the temperature measurement is part of a safety loop, custody transfer calculation or control loop, all pipeline temperature measurement applications are good candidates for the Rosemount X-well technology.

Ryan indicated that the Rosemount X-well algorithm is currently available in the Rosemount 648 as a factory assembly with the 0085 pipe-clamp sensor.

You can connect and interact with other temperature measurement experts in the Temperature group in the Emerson Exchange 365 community.

Update: A question came in about measurement delays. Ryan notes that the measurement time response is based on many factors–material of construction, thickness, type of fluid through the pipe, etc. Consult with your Emerson sales team for help with your specific application.