Product Review: KROHNE OPTIMASS 7400

I have an interesting case to share with y’all. In my routine traveling through Brazil to promote flow devices, I visited a customer to get his feedback on the performance, technology, and features of his purchase.

I asked him how he liked setting up the transmitter using the ethernet port and built-in web server. To my surprise, the customer answered, “Ethernet port? Web server?” I told him about these fantastic features before he bought the devices! But apparently, he didn’t care enough to even remember, much less use these features.

If the company doesn’t have the mindset for new technology, then the finest new tech in the world won’t make a lick of difference. So don’t choose a device based on the features if you or your company aren’t ready to handle them. Focus on accuracy and repeatability.

Today, we have the KROHNE crew coming to Visaya again with a premium flow meter for this review, the OPTIMASS 7400. Let’s check it out to see if it can fit in your application!

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?

I like the KROHNE design for this meter. It feels robust! Moreover, it has an amazing display and white backlight that you can use to configure the transmitter in the field. This LCD screen is 256 by 128 pixels! I really like the color and the size of it; the data shows up clearly on the screen.

Courtesy of KROHNE

The front of the device has four push buttons to set up locally without software or tools. The company offers compact and remote versions too. The touchscreen – called the optical key – provides a good user experience for the configuration. It also touts an infrared interface to set up the device without opening the housing. That’s fine, but I’d rather see Bluetooth or wireless here.

Integration can tip the balance between Brand A or Brand B. But since most processes still run on analog, you can always get seamless integration! Am I right? Anyway, the OPTIMASS 7400 can integrate with your control system through HART, FOUNDATION Fieldbus, PROFIBUS PA, PROFIBUS DP, and Modbus RTU. It also comes with good old analog, pulse, frequency, and status. They still lack Ethernet protocol for this model, but you can have EtherNet/IP in another model.

Courtesy of KROHNE

The OPTIMASS 7400 ranges from a quarter inch to three inches, and you have extended list of wetted material for chemical compatibilities, such as titanium, stainless steel, Hastelloy®, or tantalum.

What can it do?

Easy, right? The OPTIMASS 7400 can measure mass flow, density, and temperature! And you can also figure out volume flow, referred density, concentration, and velocity! Just what you expected. The accuracy looks pretty good, though. Mass flow in liquid application has an accuracy of +-0.1 percent of flow rate plus zero stability, and gas has +-0.35 percent of flow rate plus zero stability.

Courtesy of KROHNE

The standard density accuracy is +-2 kilograms per cubic meter, but if you decide to pay to have the meter calibrated on site, the accuracy jumps from +-2 to +-0.5. Nice, huh? The standard temperature accuracy is +-1 degree Celsius.

In general, the OPTIMASS 7400 brings good accuracy and repeatability. You can read all details in the datasheet or the manual.

The wetted material of the measuring tube affects the temperature range on this one. Titanium gives a range from -40 to 150 degrees Celsius and stainless steel from 0 to 100, with an extended version up to 130 degrees Celsius. The Hastelloy and tantalum versions bring similar temperature ranges, from 0 to 100 degrees Celsius.

Same goes for pressure. Titanium supports from -1 to 100 bar, and the stainless steel, Hastelloy, and tantalum from -1 to 50 bar.

Why should I care?

Because this device has some nice features. If you have sporadic air entrainment, you probably struggle to measure flow correctly in that part of your process. The OPTIMASS 7400 has Entrained Gas Management, or EGM™, that allows the meter to work with gas and liquid mixtures, slurries with gases, and more.

Courtesy of KROHNE

The device also offers advanced diagnostics with NAMUR NE 107. Of course, you can find this perk in other flow meters on the market, but it’s worth mentioning. Last but not least, you have redundant data storage, decreasing the chances of losing your data.


The OPTIMASS 7400 has both good performance to support your process and fancy features to improve it. If you’re in the market for a high-end Coriolis meter, give this one a look. You might like it.

This video has more details about KROHNE’s OPTIMASS:


Recommended articles

Product Review: Ecofrog from E-Sensorix

Featured Level Product Review

Product Review: NOVUS Logbox Wi-Fi

Articles Product Review