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Temperature
Non-invasive temperature measurement
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Redefining non-invasive temperature measurement!
For demanding applications typically needing a barstock thermowell thermometer, the non-invasive thermometer iTHERM SurfaceLine TM611 is a great alternative.
The alternative for harsh process conditions.
Superior accuracy and response time comparable to invasive temperature measurement! Process temperature measurement without the risk of leakage and flow disruption. True measurement! No electronic compensation, no calculations.Optimized thermal conductivity: Advanced geometry of the thermal coupling element for excellent heat transfer.Minimized heat transfer resistance: For optimal accuracy and response time.
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©Endress+Hauser
For demanding applications across all industries
High flow velocities High process pressures Highly viscous media Corrosive media Abrasion Pigging Small pipe diameters
©Endress+Hauser
For energy and safety monitoring
Greenfield projects Subsequent installation Temporary measurements Additional measurements Flexible positioning at various points on one pipe... ... or across different pipes in a plant
Discover how our innovative surface thermometer enhances safety in hydrogen processing, even for small pipe dimensions.
Learn how the non invasive thermometer successfully meets the challenges of temperature monitoring of a heat exchanger.
TM611 is the optimal solution for the challenges of temperature control in steam power plants in stand-by operation.
Product at a glance
Unlock superior accuracy, enhanced safety and remarkable time and cost savings with iTHERM SurfaceLine TM611. Discover its versatility across heavy-duty industries and learn how it can help you overcome application challenges.
Unique product design - leading to superior accuracy and response time!
Unique product design iTHERM SurfaceLine TM611 is designed with carefully selected materials, precise surface finishes, and advanced geometry to ensure the most uniform heat transfer possible.
Superior accuracy A comprehensive thermal analysis, qualified by extensive testing, and the significant reduction in heat transfer resistance result in superior accuracy, even compared to invasive thermometers.
Our study shows that the response time of the Endress+Hauser TM611 is better than many invasive thermometers with straight thermowells, and has fewer measurement errors at shallow immersion depths.
Marc Schalles
Research engineer, TU Ilmenau
It could hardly be easier to determine the ΔT of a heat exchanger without making any changes to the pipework. Direct comparison measurements show a deviation of ±1°C, which is sufficient for us.
Andreas Kohrs
I&C Planning, Sasol Germany GmbH
iTHERM SurfaceLine TM611 enables the integration of precise temperature measurement - without any mechanical modification / plant downtime. A very interesting solution for our ongoing production.
Maximilian Lindinger
EI&A Engineer, Clariant Produkte Deutschland GmbH
FAQ - frequently asked questions
Is the response time slower than with an invasive thermometer?
The fastest way to measure temperature is with a thermometer that is in direct contact with the process (without a thermowell), e.g. an iTHERM QuickSens or grounded thermocouple. However, this is not feasible in many applications.
As soon as a thermowell is used, the response time becomes significantly slower. Although there are several optimization options for thermowells, e.g. TM131 with fast-responding thermowell QuickLink, in most of the applications standard thermowells (barstock with bore diameter 7 mm / 0,039 in) and standard thermometers are used.
A comparison of iTHERM SurfaceLine TM611 with a barstock thermowell with standard bore diameter results in the same response time for both variants. The insulation of the measuring point has not yet been taken into account, but will improve the results even further.
If response time is a decisive factor for the application, an optimized invasive thermometer can be the right solution, however there might be the need for a customized design.
How can the accuracy be the same as for invasive thermometers? What about convection and conduction errors?
The heat transfer from the medium to the sensor element is the decisive factor for fast and accurate temperature measurement. In pipes or containers, this can usually be achieved with a direct immersion thermometer without a thermowell. However, this type of application has various disadvantages and cannot be realized in all applications, because the sensing element would be damaged by all sorts of influences.
For this reason, indirect measurements are used. Even a direct contact thermometer uses a mineral insulated metal cable to protect the sensing element to some extent. An indirect measurement in a thermowell is therefore similar to a surface measurement but has to cope with additional thermal masses and transitions. The influencing factors are identical for these measurements: heat transfer resistances at every boundary layer, heat conduction and heat dissipation errors in every material, influences from heat radiation as well as influences from convection. The overall target must be to guarantee optimum heat transfer to the sensing element and at the same time reduce the environmental influences as much as possible.
With iTHERM SurfaceLine TM611, this is achieved by optimizing the geometry of the coupling element, which serves as a “heat collector” and “heat conductor” to the sensing element. The thermal contact to the pipe is close to perfect (surfaces, contact pressure, geometry). In addition, the thermal mass of the sensor is reduced. Environmental influences can reduced through the recommended insulation of the measuring point.
Does the transmitter compensate ambient influences electronically and correct the measurement result?
No. The transmitter converts the measurement signal into a standardized and stable output signal. Due to the optimized heat transfer design, iTHERM SurfaceLine TM611 is measuring highly accurate – there is no need for electronic manipulation of the measured values.
How can measurement results be improved and negative influences by ambient conditions be reduced, especially outdoors?
Every temperature measurement, whether invasive or non-invasive, is influenced by its environment. The key factors to significantly reduce these influences in non-invasive temperature measurement are proper insulation and an intact heat transfer material on the coupling element. iTHERM SurfaceLine TM611 performed better than comparable products in both laboratory, climatic chamber and outdoor field tests, with all measured points insulated.
The type of insulation material depends on the operating conditions. Our tests, which delivered very good results, have been carried out with an U-value of 1.33 W/m²K. We recommend heat insulation of the coupling element against the environment over a length of 100 mm (3.94 in) on both sides of the coupling. The maximum permissible thickness of the insulation depends on extension neck length E and can be calculated using the formula in the technical documentation.
Are there any restrictions regarding the material or surface of the pipe?
The thermal conductivity of the pipe material plays a key role for accurate and fast non-invasive temperature measurement. Materials with higher thermal conductivity enhance heat transfer, leading to improved measurement results.
To achieve optimal heat transfer to the coupling element, a smooth, clean surface is essential. Coated surfaces, by contrast, have a lower heat transfer coefficient. However, depending on the application, special coatings (e.g. for corrosion protection) may be necessary, which can result in less accurate or slower measurements.
What are the communication protocols available with the device?
iTHERM SurfaceLine TM611 includes all Endress+Hauser iTEMP temperature transmitters with standard communication protocols (4-20 mA, HART, FOUNDATION Fieldbus, PROFIBUS PA, IO-Link, PROFINET over Ethernet-APL) and optional Bluetooth® connectivity.
Can individual components (e.g. insert, transmitter, housing) be replaced or should the entire assembly be replaced?
As iTHERM SurfaceLine TM611 is a modular device, several options are possible. The complete thermometer can be replaced, only the transmitter, or the connection head. The measuring insert is not replaceable. In case of sensor drift over time, we recommend ordering a new TM611 without the coupling element and transmitter. This way, those parts can be reused to save on OPEX costs.
In addition, we offer different spare part sets with mounting material like the screw clamps and the heat transfer material that fits in between the coupling element and the pipe.
What should be considered for the installation on the pipe?
Coupling element in the right size. The pipe diameter must be accurately reflected in the coupling element! Measuring with a bigger or smaller pipe diameter would not work well. Our tests showed significant deviations. Smooth and clean pipe surface. Smaller tolerances and damage on the pipe surface are largely compensated by the heat transfer material (foil) on the coupling element. Please watch out for weld seams, dust and corrosion. Intact heat transfer material. When using TM611 as temporary measurement you need to make sure the heat transfer foil is still properly attached before using the device at a different spot. If the foil is damaged during removal, you can replace it with the appropriate spare part.
I have more questions about iTHERM SurfaceLine TM611!
For detailed technical information, installation guidelines, certifications, and more, we recommend the technical product documentation .
For further questions, feel free to contact us via the contact form below, and we’ll be happy to answer them.
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iTHERM SurfaceLine TM611
Explore the product in detail and use the configurator to discover all available options, from temperature transmitters and sensors to approvals.
Technical documentation (TI)
Access detailed technical specifications, information on mechanical construction, mounting and insulation, and more.
iTHERM SurfaceLine TST602
Discover our alternative, fundamental surface thermometer for basic monitoring applications.
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