Product Review: FFU flow sensor from SICK

Before we tackle the FFU in today’s review, let’s talk about why we pick a device carefully instead of just sticking in the first gadget that says it’ll do the job. In an industrial process, each device has a unique position, because each position has certain requirements to fulfill its function within the process.

Nonetheless, some applications have fairly common needs or low standards. For those, you can pick conventional devices that meet the minimum requirement to work correctly in that application.

Today, we’ll revisit the world of flow, because it’s a big world with lots of nooks and crannies we haven’t checked out yet. You can find many sizes and types of flow meters, but some small flow ranges need small flow meters.

The company SICK developed the FFU, a non-contact flow meter, for this sort of application. Let’s dive into the features and figure out where it can fit in a new process – maybe yours!

Disclaimer: This product review examines only features, not performance. If you’ve used this device, feel free to share your experience in the comments. This content serves the purpose of providing information if you want a new device.

Whatcha got there?

The FFU works using the transit time method. We have an article that explains the principle, if you want to learn more.

image of Flow sensor FFU
Courtesy of SICK

Anyway, this compact device can fit in your hand. You can configure it with the local membrane keypad, and it only takes a few seconds to figure out how to navigate the menu tree.

I didn’t find the  display details on the documentation, so I can’t tell you the exact size of it, but as you can see, it’s tiny. The tiny display nevertheless shows you the data you need.

As I mentioned before, SICK built the FFU for small pipes, but you can choose from four standard sizes – DN 10, DN 15, DN 20, and DN 25.

What can it do?

As a non-contact ultrasonic flow meter, the FFU can measure non-conductive and conductive products as well as temperature. The technical documentation from SICK makes this meter sound good performance-wise. But a vendor would say that, huh? Anyway, let’s go with it until someone says otherwise.

The FFU can provide an accuracy of two percent of the final value and one percent of reading, within about three millimeters per second with the calibration report. You can see the reference conditions in the docs, but you can expect a performance similar to that.

image of Flow sensor FFU
Courtesy of SICK

You can also use the FFU in process pressures up to 16 bar for the DN 10 and DN 15 and 10 bar for the DN20 to DN25. Operating temps range from 0 to 80 degrees Celsius. And of course you need to check the wetted part and housing materials for fit in your process.

Beyond that, it has an enclosure rating of IP 67. And the website has some examples of where you can apply it without any issues, such as with cooling circuits and welding guns.

Why should I care?

Well, you have two options for input/output. For the first, you can have an analog output of 4-20mA or 0-20mA for flow and temperature and one pulse/status. You can also get PNP/NPN-transistor output where you can read flow rate, empty pipe detection, and more.

image of Flow sensor FFU
Courtesy of SICK

For the second, you get two pulse/status and a switching input which you can use to reset the dosing or the counter. These options make it easier to integrate the FFU into your control system.

Lastly, it handles a range from 0 to 240 liters per minute. Naturally, that depends on your process, but you can put your process numbers in when you scale it out.


The FFU brings a smart range of possibilities at a low cost as well as the flexibility of measuring conductive or non-conductive products. As a maintenance-free device, if you have a problem, then you’ll need to buy a new one. Some folks will consider this a plus, but as always, your mileage may vary.

If you want more options on the market to compare this meter with, check out our device directory on the right. You can also read more about the FFU on its page here at Visaya.

This video has more about the flow sensors from SICK

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