A new future for non-invasive temperature measurement [sponsored]

Historically dismissed as inaccurate, surface-mounted temperature measurement has evolved. Now it can offer the same accuracy and response times as invasive temperature measurement – without process interruption.

Temperature measurement sits at the heart of industrial process control, with accurate data underpinning safety, quality, efficiency and regulatory compliance. For decades, invasive temperature measurement techniques have been favoured, yet these are not always suitable for demanding applications with high pressure, high flow velocity or corrosive/abrasive media. Now advances in technology have renewed interest in surface-mounted, non-invasive temperature sensors.

Downtime and contamination risks

Traditional methods offer direct contact with the process fluid, typically delivering high accuracy and fast response. However, installation requires downtime, cutting and welding, and contamination risks arise in regulated industries. On the other hand, surface-mounted measurement – placing the sensor on the exterior of the pipe or vessel – removes process intrusion. Once dismissed as imprecise, in part due to the effect of external influences such as ambient temperature, surface-mounted measurement is increasingly viewed as a viable, low-risk alternative.

Manufacturers have taken different routes to try to reduce the impact of external influences on surface-mounted temperature sensors. One approach takes two measurements and uses a mathematical algorithm to calculate a synthesised process temperature. However, as this is an artificially produced value, inaccuracies can result, prompting concerns around safety and regulatory requirements.

A new approach

Endress+Hauser’s iTHERM SurfaceLine TM611 takes a different approach. The sensor is based on an enhanced thermal coupling element, which is shaped to match the outer diameter of the pipe and coated with a heat-transfer material. This material deforms during installation, ensuring that any imperfections in the pipe – scratches, pitting or corrosion – are filled. This stops air pockets from forming and affecting heat transfer.

Field trial data from the power & energy industry shows that the TM611 reliably follows the temperature development of the process, comparable to invasive temperature measurement, whereas the sensors relying on electronic compensation are affected by environmental influences such as wind and ambient temperature changes.

For organisations balancing safety, cost, uptime and energy management goals, non-invasive solutions offer compelling advantages – particularly in retrofit and high-risk environments.

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