Product Review: Proline t-mass 65I

We have the Proline t-mass 65I in the house! Yeah! What? Never heard of it? Wait, never heard of thermal flow meters?! Sure, they’re not as popular as  magmeters or Coriolis meters, but these gadgets can help save money in some applications. So you should check them out!

Believe it or not, I’m pretty familiar with thermal flow meters. Yup, as a product manager in Brazil, I supported my sales colleagues in selling a bunch of these devices.

proline t-mass 65I
Courtesy of Endress+Hauser – Proline t-mass 65I

Now, this sort of meter works great – if you meet the minimum requirements. And I emphasize that because humidity and other factors can affect these sensitive little gizmos. Of course, the vendor will suggest installation tips to avoid this sort of problem, but sometimes they still don’t work as well as they should.

Back to the t-mass 65I! Don’t ask why it isn’t capitalized. Endress+Hauser does it that way on the company site, and we try to respect the official word. Anyway, let’s get into the nitty gritty about how it works and whether you can fit it in your process.

Stick with me, and let’s see the pros and cons of this thing!

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?

You’ll find the t-mass 65I in plenty of applications across segments where it has worked for a long time. It makes up a small part of the old guard, where you’ll also see brands like Fox Thermal and Sierra Instruments. As a consolidated device, you can deploy it in similar processes without problems. However, if you want new features, then you should probably shop another model.

So the first impression is positive; this meter follows Endress+Hauser’s standard design. You can add a display to read the process variable and diagnostics. The display will also help you set up locally, using the three push buttons in the front.

Proline t-mass 65I
Courtesy of Endress+Hauser

You can get an integrated transmitter or an external, which may provide easier access to your device’s data.  As for the sensor, this meter has no flanges; you insert the sensor directly in the pipe. On the upside, this type of sensor can save money in installation over the flanged solution. On the downside, you must pay attention to the length of the sensor and the flow direction. Why? Because I’ve seen problems stemming from these issues before.

What can it do?

You can measure mass flow of industrial gases and compressed air. You can also use it in a variety of segments and in pipes from 3 to 60 inches, giving you a wide range of possibilities.

It shows up a lot in energy monitoring system projects as additional devices dedicated to this solution. There, its easy installation can save money and enable the entire project.

It can also measure mass flow, volume flow, temperature, and energy flow. Not bad, right?  Its flow range goes from 20 to 720,000 kilograms per hour, with a pressure range from -0.5 to 20 bar gauge and process temperature from -20 to 60 degrees Celsius. You can opt into -40 to 60 degrees too, if your process runs a little chillier.

And now we come to the sensor and housing materials! The t-mass 65i has sensors in stainless steel or Hastelloy C22 and a housing of powder-coated die-cast aluminum. You’ll find other materials for the insertion tube, transducer guard, compression fitting, and so on.

Why should I care?

Because the Proline t-mass 65i can save you money if you can work within its limit. And you have plenty of applications where you can fit it, as the gases feature definitely expands the possibilities.

You can integrate it into your control system in a multitude of ways. If you don’t have digital protocol, then you can incorporate it using analog, pulse, frequency, or status. Now, if you want to get the field data digitally, then you can select HART, PROFIBUS DP or PA, FOUNDATION Fieldbus, and Modbus. Besides those outputs, you can pick analog or status for your inputs. Pretty good, huh?

The transmitter has an integrated gas engine, although you can define the gases mixtures yourself if you prefer to get more hands-on. You can select air, ammonia, butane, carbon dioxide, chlorine, ethane, neon, nitrogen, and a bunch of others.

Last but not least, you have several approvals and certifications, such as ATEX II 2GD, NEPSI Ex de IIC, stuff like that.


The Proline t-mass 65i brings a bunch of experience in different segments and applications. You can scale out the device online and see how it does with your specs or call a sales rep to help you.

Buy the Proline t-mass 65I in our online shop


Find and buy the right thermal flow meter for your application

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