Podcast: Radar Level Measurement — Challenges, Benefits and Innovations

Joe Incontri from KROHNE explains to Processing’s Managing Editor, Daniel Gaddy, how radar level measurement devices work using high-frequency time measurement technology. He covers radar's advantages over ultrasonic alternatives, including better resolution and smaller antennas, while addressing challenges like density measurement limitations and interference from dust or agitated surfaces. The conversation highlights radar's cost-effectiveness and simplified setup processes, concluding with KROHNE's pioneering role in introducing FMCW radar technology in the early 1980s and their 50-year industry experience. This podcast originated at Ear on Processing.

Transcript

Daniel: We wanted today's conversation to focus on level and open channel flow applications with radar devices in processing and manufacturing environments. To kick things off, can you explain what radar is and how radar technology differs from other non-contact techniques in processing applications?

Joe: Yeah, certainly. So radar is basically—it's a time measurement device, and we use high frequencies to emit a signal into the air, and we wait for a reflection from something, and we measure that time it takes for that reflection to travel back. And that whole cycle is basically a measure of distance. And that measure of distance basically is what we use to measure level. In order to do so, we need to understand what the total range is. [00:01:30] So we basically subtract the distance we measured from the total range, and that gives us the level inside the vessel.

Daniel: And to follow up on that, what are some applications that are now best tackled with radar?

Joe: Well, so radar is kind of an evolutionary thing. I mean, there's been different technologies that had the same basic idea, and radar is basically a set of frequencies. So anything above the gigahertz range would be—or high kilohertz range—would be referred to as radar signals. Anything below that would be ultrasonic. So if you have something in the kilohertz or hertz range and you use it to measure the same way that radar does, we would call it an ultrasonic meter. So because it's a radar device, it's a higher frequency, and so the benefit of a higher frequency is it gives you more resolution to work with, so you get a finer signal. So in terms of how it measures, fundamentally, as I mentioned, the benefit of the higher frequencies is your antenna is smaller than it used to be back in the day because you have more concentrated frequencies or more concentrated signal size. So it allows you to fit this thing into a tighter space and use it for different applications.

Daniel: And what are some challenges that are tough to overcome with radar level?

Joe: Well, as you might expect, it's not a perfect—it's not a one-size-fits-all [00:03:00] kind of technology. There are some applications that might be a little difficult. Well, for example, we don't know what the density of the product that you're measuring is. So if you're trying to get a mass of what's inside the vessel, well, you still have to use something like a weight scale or plug in a certain density of the product to give you an approximate density or approximate mass. You multiply the volume that you would have to calculate based on the vessel that you're measuring in by some kind of density [00:03:30] to get your mass. So that's one thing that radar can't do intrinsically, except by a workaround. The other thing that sometimes is a challenge for radars is if you have a lot of dust, or if you have a lot of solids that are between the emission—the antenna—and the surface of the product in a solids application. Or if you have a very fast-moving surface or a widely varying surface, like a wavy, agitated surface, it'll measure, but you're never quite sure how accurate the measurement is because the device is trying to process all that movement into a level measurement. The other thing that sometimes is difficult for a radar device is if you have a very dense foam or if you're trying to measure an interface level inside a vessel. So sometimes you have two liquids and you're trying to measure where is that layer, how thick is that layer—the top layer on the vessel? Maybe it's oil and water. Sometimes you can do it quite readily, but sometimes, depending on the products, the fluids that you're trying to get the interface, it might be more difficult. So those are the kinds of things that you might want to consider. I'm not saying it can't be done; I'm just saying that those are the kinds of things we need to gather more information on before we can give you a definitive answer.

Daniel: And are these radar devices easy to set up and maintain?

Joe: Yes. The simple answer is, in this day and age, yes, very much so. They have a high-capacity processor inside. So the user interface is much, much simpler than it's ever been. There's only a couple of parameters you have to worry about now. So you just—as I've mentioned, generally speaking, you have to set the type of vessel you have or you're working in, and it's basically multiple choice. You don't even have to describe it very well. You pick: is it an agitated tank, is it a vertical tank, is it a horizontal cylinder, is it a silo? Basically, you pick from a multiple choice menu, and then what is the total height of the vessel and what is the range that you're trying to measure? And those are generally the parameters you need to know. Sometimes you might have to put in, like I say, the density of the fluid, or in exception cases, you might have to put in a couple more things, but it's all very simple user interface. And it can be done on a computer, a phone. Even now there's apps for setting up the devices, and it's a visual interface. You don't have to have a manual in front of you to actually guide you. And oh, by the way, there's YouTube setup videos that you can go to also to help you in understanding what we're trying to get at in terms of the setup. So yeah, it's not what it used to be.

You can't see me—this is a podcast—but I've got a lot of gray hair. So back in my day, you'd have to read a manual and you'd have to plug in the information with parameter codes and all that kind of stuff. So it was a lot more complicated than it is right now.

Daniel: Yeah, YouTube videos are always a good help. So what do people need to know before they start shopping for radar level devices, and how do they get the best bang for their buck?

Joe: Wow. So that's a great question. So as I mentioned, what you need to know is as much as possible about your application. Basically, once you have that, you can figure out: is radar the right solution? I will tell you that the technology has become much more cost-effective now. So radar devices are probably your cheapest solution at this point. If you're looking for an entry-level type device or a device for what I would call a nominally general-purpose or general application—not too complicated—radar devices are probably your most cost-effective solution. They're even less expensive than ultrasonic devices in some cases, which used to be what was most popular for simple applications. So in terms of the best bang for your buck, you're hard-pressed to find something more cost-effective and more adaptable than radar. In this day and age, I will say, as I've mentioned before, there are some applications that you might have to pick a higher-level technology to be able to handle different solutions.

For example, if it's a solid application, you would have to consider the angle of repose. When you're filling the vessel, you'll have a cone that builds up, and when you're drawing down the vessel, you'll get the inverse cone. So you basically have to teach the instrument—to be able to set up the instrument to adapt to that particular installation or that particular situation. And sometimes the low-cost versions are not your best application, or not the best tools to use for that application. So a vendor can help you discern what's the best technology for your application. Now, in terms of the bang for the buck, as I mentioned, you'd be hard-pressed to find something better adapted right now than radar technologies. The other thing you might want to know before you delve into this is what are you going to hook this thing up to and what kind of power do you have available? Because sometimes some of the technologies—most of the technologies are 24-volt DC and they're loop-powered, but in some cases you might also want to exchange information on a digital protocol of some sort. So those are the things I would recommend that you consider in terms of the technology and how to get the best bang.

Daniel: And for those who aren't aware, how long has KROHNE been in the game?

Joe: Well, so that's one of the things we're really proud of. We were the first company to actually introduce an FMCW radar. So that's a lot of letters, but FMCW stands for Frequency Modulated Continuous Wave. So just like AM versus FM—AM was basically—Amplitude Modulation was basically what AM stands for, and you basically put more power in to get more signal back. Whereas Frequency Modulated is you basically have a set of frequencies that you modulate at the same power level. So the advantage is that FM-type technology can travel further in a more challenging environment. And from an industrial standpoint, the big benefit for KROHNE was that we used less power than amplitude modulated radars before. And so that made a difference. And the Continuous Wave is basically, as opposed to sending a signal and waiting for bounce-back—so there's a time delay between the measurement that could be significant in some cases—Continuous Wave was basically always listening for the reflection.

So responsiveness to rapid changes in levels was also a big, big benefit to FMCW technology. And so KROHNE introduced that in the early eighties, which was well ahead of anybody else at the time, but we were kind of pioneers. So as a German company, most of those innovations were absorbed or really introduced in Europe and easily adapted in Europe, but it took a little while for them to be adapted here in other parts of the world—in North America and so forth. But we are very, very proud of the fact that we've been in this business for 50 years at this point.

Daniel: And lastly, how can our listeners find out more about KROHNE and its instrumentation offerings?

Joe: Yeah, so basically krohne.com is the place you want to go, and just look up the US to get our contacts here in the US or Canada, if you're from Canada, and you'll see all of the product offerings right there. You can also send an email to [email protected], or we have a phone number. It's easy to remember. It's 1-800-FLOWING—F-L-O-W-I-N-G—and you'll be able to get a hold of somebody who will be glad to get back to you. We also have, on our website, you'll be able to find your local sales channel partner by typing in your zip code on the Find Your Local Sales Channel Partner page.