Product Review: Endress+Hauser iTHERM TrustSens TM371

Let’s talk temperature! Today, we have an outstanding device for the food and beverage or pharmaceutical industries. Endress+Hauser has launched a new thermometer and kindly sent us one so we could learn more about it.

Furthermore, Endress + Hauser Messtechnik GmbH + Co. KG wins the HERMES AWARD at Hannover Fair 2018, one of the most prestigious industrial awards in the world. You can read more about the nomination here.

Hermes award 2018
Endress + Hauser Messtechnik GmbH + Co. KG wins the HERMES AWARD 2018 – Courtesy of Hannover fair website

Stick around and see the pros and cons of the new iTHERM TrustSens TM371!

Disclaimer: This product review examines only features, not performance. If you’ve used this device, feel free to share your experience in the comments.

Whatcha got there?

The newest thermometer from Endress+Hauser, the TM371’s simple design hides some of the fanciest tech for temperature calibration on the market. But wait, we’ll get to that later. Let’s go back to its design.

We often crack jokes about design because it doesn’t matter much in other applications, but it does here. Big E created the TrustSens TM371 for hygienic and aseptic processes, and its compact design reflects this purpose, allowing you to fit it almost anywhere to reduce contamination risks.

If you want a local display, it doesn’t have one built in, but you can get a standard solution, the loop-powered RIA15. Frankly, I like Endress+Hauser’s efforts to promote the RIA15 as its top solution for local visualization and setup. Keep in mind, though, that it won’t do setup on all devices.

In general, the RIA15 provides a good user experience and flexible installation. You can integrate the TrustSens into the control system with analog or HART communication. Considering its focus, those options are more than enough. However, some companies offer PROFIBUS and Ethernet. These protocols would make a nice upgrade on this device.

Courtesy of Endress + Hauser

What can it do?

It can measure temperature using the principle of resistance temperature detection or RTD. It uses a PT100, which means it can measure from -40 to 160 degrees Celsius. Pretty nice range – you can cover most applications in the hygienic/aseptic industries. It can also withstand process pressures up to 50 bar.

You can request the maximum immersion length, and the order form gives you plenty to choose from. Some of the numbers don’t match, though. The website has the max length up to 900 millimeters, but the configuration tool only goes to 700.

TrustSense TM371
Courtesy of Endress + Hauser Max. immersion length

Answer from Endress+Hauser: “The immersion length up to 900mm is on request while the 700mm is available as a standard.”

You can ask your local sales rep about it if you need to know now. Anyway, you can configure the device to have a straight or reduced tip. On the technical documentation, you can see the difference between these options.

Finally, you can get the sensor with the thermowell included or not. The order form lets you tweak the thermowell external diameter, the external diameter and length of the insert, and other options.

Why should I care?

Usually, thermometers have slowpoke response times. Your PID control of the process will need faster action on the final element. However, even though the temperature doesn’t change fast, the sensor should detect this change quickly.

The TrustSens TM371 has some zip. The manual has nice tables with the values according to IEC 60751, with and without heat transfer paste. Take a look at the table with the heat transfer paste.

TrustSens TM371 heat transfer table
Courtesy of Endress + Hauser

Hygienic and aseptic applications require different process connections, but for either you should avoid adapters. Big E has been around this block a time or two, so the TrustSens TM371 has an extensive list of process connections: clamp, weld, compression fittings, and others.

But never mind all that. Check this out! This device calibrates itself! A reference calibration in the sensor means you don’t need to pull it and dunk it in a bath. So awesome.

The self-calibration uses the Curie Temperature (Tc) procedure and a ceramic body for its reference. At 118 degrees Celsius, the ceramic body will change. During sterilization in plant (SIP), you need to heat the process above 118. When the temperature drops back to 118, the ceramic body changes, and the device will use that to calculate the deviation of the sensor.

A local green LED indicates the calibration, and the sensor will save the results automatically. Through a plant asset management system, you can see the report and print it out if necessary.

Last but not least, you have the option to choose the iTHERM QuickNeck to install and remove your sensor easily. You can also choose your protection classes, such as IP67, 68, and IP69K.


Yep, the iTHERM TrustSens TM371 brings a lot of innovation to the humble thermometer. However, I wish it had the new Bluetooth protocol Endress+Hauser put in its other devices.Still, if you have a simple application and temperature is critical to your product, then you should compare the cost benefits.

Buy the iTHERM TrustSens TM371 in our online shop


Find and buy the right thermometer for your application

This video has more info about TrustSens technology:

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