Automated thermal conductivity measurements made easy

Thermal properties the simple and precise way

When you need to know how well soil or other media can draw heat or ensure thermal retention, traditional measurement options are time- and labor-intensive. In this webinar, METER product manager Shaun Weldon explores a new, more automated method of measuring thermal conductivity — The VARIOS. He will discuss:

• Why thermal properties of soil need to be measured, and how that led to the development of the VARIOS
• How to measure thermal conductivity at every moisture level
• How this technology is being used in geotechnical and research projects worldwide
• How to measure thermal conductivity and soil moisture release curves simultaneously
• How VARIOS meets compliance standards for thermal conductivity measurements
• And more

Next steps

• Link to slideshare
• Explore the geotechnical engineering solutions hub
• Watch Thermal properties of stony soils: How to get the right answer in a soil/rock mix
• Listen to We Measure the World Podcast Episode 34: Bushfires, the Great Barrier Reef, and white-bellied frogs
• Learn more about the VARIOS
• Follow us on LinkedIn: https://www.linkedin.com/company/meter-group
• Questions?

Our scientists have decades of experience helping researchers and growers measure the soil-plant-atmosphere continuum.

• Talk to an expert
• Request a quote

Transcript:

BRAD NEWBOLD 0:07
Hello everyone, and welcome to automated thermal conductivity measurements made easy. Today’s presentation will be about 30 minutes, followed by about 10 minutes of Q & A with our presenter, Shaun Weldon, whom I will introduce in just a moment, but before we start we’ve got a couple of housekeeping items. First, we want this webinar to be interactive, so we encourage you to submit any and all questions in the questions pane, and we’ll be keeping track of these for the Q and A session toward the end. Second, if you want us to go back and repeat something you missed, don’t worry. We will be sending around a recording of the webinar via email within the next three to five business days. All right, with all of that out of the way, let’s get started. Today we’ll hear from Shaun Weldon, who will discuss a simpler way to generate automated thermal dry out curves. Shaun operates as the SATURO, HYPROP, and Tensiometer product manager here at METER Group with over 12 years of experience helping researchers measure the soil, plant, atmospheric continuum. So without further ado, I’ll hand it over to Shaun to get us started.

SHAUN WELDON 1:06
Thanks, Brad, um happy to be here today. I want to just start our presentation today, talking a little bit about just the basics of thermal conductivity, what it is and why it’s important to us. So thermal conductivity is a measurement of a materials ability to transfer heat. It’s affected by a lot of different factors, including the density of that material, the pore sizes that are present there, which which also leads to soil texture, the mineral composition of the of the sample can also cause heat to transfer differently. Certain minerals are better at transferring heat than others, and so that will need to be taken into account. But the thing that has by far the largest influence on thermal conductivity is that moisture content of the soil, moisture water, in particular, is very good at transferring heat. So the more moisture content you have in a in a material, generally, the higher that thermal conductivity is going to be. So thermal conductivity, especially in soil, is very important in a number of industries, including the ones shown here on the screen. We’re going to focus mainly on the ones on the left hand side of the screen today, just because those are the ones that we deal with most here at METER Group. We’ll talk a little bit about how it’s used in each of these industries and why it’s important to them here in the next couple of slides, and then we’ll get into the VARIOS system itself and how that’s used. So the first one that we have is agricultural applications. Probably the biggest application for agriculture of thermal conductivity is seed germination. Most seeds need a certain amount of heat before they’re actually ready to start sprouting and growing, and this the thermal conductivity of the soil directly impacts this as heat is transferred from the sun into that soil, and a soil with good thermal conductivity is going to be able to transfer that heat to the seeds to give them that energy that they need to start doing that germination process. This tells the seeds when it’s time to start to start growing, so that they don’t come out too early and get damaged by frost, and also so they don’t come out too late where they’re not going to get the moisture that they need. The next thing is soil amendments. A lot of a lot of crops are used now soil amendments, such as fertilizers, like manure, compost, biochar, is being used a ton right now in agricultural applications, because it does help hold water and also retain heat. These amendments are going to change how well that soil will transfer heat to the seeds. You want to make sure that you kind of hit that sweet spot to where there’s enough heat to get that plant the energy that it needs, but not so much that you’re drying out the surrounding area and damaging the plant material as well. Here in the northern latitudes where we live frost is a big problem, as we’re seeing right now. In Washington State, there’s a lot of frost going on. So mulch and frost protect protection are things that we use a lot of thermal conductivity to measure, as you can see in that bottom image there, there’s a lot of applications where mulch will be placed on top of of the soil to help retain that heat. Because the mulch has a lower thermal conductivity, it holds that heat in. It helps it stay in the soil so it gets where it needs to be and then kind of on the same the same vein at the end of the season right now. A lot of people are placing hoop houses up so that the crops are protected as long as they can, so they don’t get frost damage as we start to get into the winter here, your planting schedule is also going to be determined a lot by the heat of your of your system, and using different materials and methods to try and get those that soil to to retain that heat is a big thing. Environmental applications. There’s a ton of these right now that we’re we’re working with a lot of different groups to try and understand better the how thermal conductivity affects these things. For example, heat exchange with the atmosphere. As we start to see more warming due to climate change, this becomes a very, very big topic hit the wrong one there. Sorry. So that heat exchange from the Sun to the ground, from the ground out into the you know, atmosphere, as we start to see more man made materials and more bare land, that helps that causes some of that problem is that heat is that would have normally been absorbed or reflected by plants, is now being absorbed by the the other materials, and it’s just radiating out to the atmosphere, which is exacerbating the problem of climate change. Urban heat islands is another huge issue that we’re seeing as we start to spread cities and towns with more surfaces that are not natural, things like asphalt and concrete, those behave much differently than what the natural state of those would have been. They absorb heat, and then they re radiate that heat later. So you’ll, you know, a lot of urban centers or places where there’s, there’s construction and infrastructure, see several degree differences from the surrounding areas make them much warmer. Trying to find materials that have different thermal conductivities that will transfer that to the ground, or that will reflect that can help to lower those temperatures as well. Soil carbon storage is a huge issue right now, as we start to get warmer, some of those, some of that carbon storage that we see in soil is being released because as that soil is transferring the heat lower and lower, because there’s more energy in the system, we start to see greater microbial activity and greater decay of things like wood and things like that that are just in the soil, that organic material is releasing a lot more carbon dioxide into the atmosphere. And this is one of those that’s a, you know, positive feedback loop where we start to see more carbon released means more energy means warmer which means more carbons released. And it’s kind of a cycle that we’re trying to better understand and figure out how to break. Contaminants in the soil are also being affected by thermal conductivity as well. Movement of pollutants is interest is influenced rather by the thermal conductivity, seeing how water moves through systems, seeing how, how that’s affected by that it can carry these, these pollutants and contaminants through the groundwater, and that thermal conductivity does influence how that, how well that moves through there. We’re also seeing a lot of remediation efforts, which we’ll talk about here in a second, that are that are dependent on this thermal conductivity of the soil and other and other mediums that it’s moving through. And then finally, in this one, the forest canopy and soil heat exchange. As we’re losing more forest, we start to see these, these bare patches in forests that help that cause a lot more heat to build up in the forest. And it’s, it’s actually mostly designed for a lot of the forest canopies are are have evolved to reflect that, that radiation back and not heat up the area. But as we’re getting these clear cut and patches in there, that’s that’s changing the way that the forest is behaving. Some in some engineering applications. These are, this is a group that we work with quite a bit as we’re looking at insulation materials. And also, you know, this goes not just for building and things like that, but also for insulating foundations and underground um, underground buildings as well, using soil to insulate and other materials insulation materials, understanding that thermal conductivity is critical to reducing energy use and making things more efficient. We’ve done a lot of research as well and collaboration with people that are researching slope stability and landslide prevention, and we’re starting to understand better how thermal conductivity of those soils can affect the slope stability. As as things freeze and thaw, it can cause that stability to change, and that’s going to change based on how well that soil can conduct heat, primarily with with the moisture level in that in that soil. Thermal regulation is another thing that we’ve we’ve worked with a lot of people on recently.

SHAUN WELDON 10:57
This has to do with things like building underground buildings, basements, subway tunnels, things like that. If you have a soil or material that doesn’t move heat away from those sources, you can have a lot of thermal issues in those temperature issues, I should say, in those buildings and applications, that’s going to cause a lot more energy use to try and regulate that temperature, to make it comfortable for people. So making sure that we have materials that can can move that heat away is is key to making sure that we’re not using more energy than we need to. And then kind of what we touched on in this last one, there’s soil remediation. There’s several methods for removing contaminants and contaminants from the soil that rely on that thermal conductivity, such as steam injection or thermal desorption or even vitrification of of toxic materials in soils, these rely on the soil’s ability to transfer that heat to actually remove these, these contaminants from the soil. So understanding how well that soil actually transfers the heat will be a key to helping us successfully remove these contaminants. Climate change is kind of on everybody’s mind right now. There’s a lot of research going on for permafrost change and what that’s doing to increase carbon emissions right now. Everywhere up north, the permafrost is starting to thaw at higher and higher latitudes, and we’re seeing a lot of these particularly organic, rich soils, such as peat and things like that, are thawing, and as they’re heating up, then microbial activity is increasing, and it’s releasing not just trapped carbon, but also methane and other gasses that contribute to that greenhouse effect that is, in essence, just creating more heat, which is causing more to melt, and it’s moving That problem farther and farther north. So we’re seeing higher inputs of greenhouse gasses from this so understanding how thermal conductivity of those soils, particularly of permafrost, how that understanding that thermal conductivity can help us understand maybe how we can slow down this process, or hopefully even reverse it at some point, carbon storage and release, we talked about a little bit with forests, but we’re seeing that all over as a result of climate change, as a result of those, the warming of our planet, And then snow pack and glacial change. As we start to see glaciers and snow pack reduce globally, we’re starting to see other materials that are being exposed that have very different thermal conductivities than the snow and the ice do. So we’re seeing more bare ground, more stone and things like that that are going to increase the heat in those local areas, which is going to just worsen that problem that we’re seeing with the with the snow pack and glacial removal, and then finally, our last one that we’re going to talk about right here is alternative energy applications. So a lot of alternative energies, such as solar and windmills, rely on buried power cables to get the power from the source to us and those buried power. Cables carry a lot of current and a lot of voltage, and they heat up quite a bit, so you need to make sure that the materials surrounding those cables are able to handle that heat load and transfer it away from the cables. There’s been a few stories in the news the past several years where those power cables have have not been properly or, I guess, the thermal conductivity has not been properly considered, and those cables heat up too much, the shielding melts, and then you get damage to cables. You get loss of power to customers, and it it’s very costly to fix. So making sure that that’s really understood and that you’re using materials that can handle that kind of heat load is is critical. A lot of the things that a lot of new energy sources, like geothermal, also ground source heat pumps. These all require materials that are good at transferring heat to and from these heat pump systems, like you see on that top image there, they require materials that can transfer heat to and from those to either cool the house by transferring heat from the home or business or whatever to the ground, or warm it by transferring the heat from the earth back up to the buildings or other places that we’re trying to heat. So if you have materials that don’t do that, these are not very effective, and they’re not very useful to us. And then there are also applications for things like solar farms that will use the excess heat from the solar panels during the day and store it in something in some kind of reservoir underground for use later in the day or later when, when the sun’s not shining. So at night time, they can use that to generate electricity still. So you need to make sure, in those cases, that you have something with with enough thermal conductivity to get that heat into it, but that’ll hold on to it so that it doesn’t just dissipate directly to the surrounding soil. And I made the alternative energy application kind of our last one, because I wanted to talk about how this led to the development of the VARIOS, which is what we’re here to talk about today. So the VARIOS is our automated thermal dry out curve instrument. It creates these for you, and it was developed by our German office as part of a project called SuedLink, which is a project in Germany where they are trying to use more renewable energy sources. So Germany made a plan to have 80% of their electric electricity generation come from renewable sources by the year 2030 and to be completely Climate Neutral by 2045 and as part of that, they have implemented a lot of both wind and solar projects across the country to to meet these goals. So in the northern part of Germany, there’s a lot of wind farms out in the North Sea and up on the shores by the North Sea, they’re generating a lot of energy that way. And then down in the south, where it’s it’s sunnier, they’re using solar farms. You can see the triangles on this map. Here are the wind major wind farm locations in Germany at the time this product project was started, which was in 2020, and then the squares on the bottom are the major solar farm locations. The the first project of this, of this effort was called soo link, which was meant to link the energy from the energy production from the northern part of Germany to the energy production in the southern part of Germany, and then also infrastructure to get that to customers, to people. Our company, our office in Germany a bit on this project to try and to try and get involved in it, because they thought it was a great project, and we had the tools to help with this. And they won contract for this original seedling project. And what they do is they’re taking soil samples along this 700 kilometer path. They’re taking a soil sample roughly every 100 meters. It varies a little bit based on the location, but it’s roughly every 100 meters at multiple depths, so that they can get the thermal conductivity of the soils that are going to surround these power cables. We talked about just a minute ago. And because these power cable because the soil is going to change its thermal conductivity based on the amount of water that’s in the in the soil, we developed the VARIOS to be able to measure that thermal conductivity of a sample from the saturation all the way down to an air dry state. Since that project has started, our office there has done around 8000 samples that they’ve processed since about 2021 since May of 2021 when the project started, and they’ve since also started working on another project. That’s it’s the same kind of project, but it’s right it’s right next to it there called the Rhine-Main-Link, and they’re currently processing over 350 samples per month on these VARIOS systems in their lab in Munich.

SHAUN WELDON 21:04
So this is the finished product, the VARIOS here, the VARIOS has at the top, you can see a sample ring that’s very similar to another instrument that we make, called the HYPROP. So those that are familiar with the HYPROP might recognize that it’s the same 250 milliliter sample ring that you take out to a field and you collect the sample on site. Or you can repack it if you have materials that don’t pack very well, such as sand and things like that, you can repack it to that density that you know. The sample rings are a little bit different in that they do have a hole for a needle sensor to go into on the side, which you can see on that picture as well. This sensor needle is then connected to the VARIOS box. This black box here, and that is what kind of runs the the whole process for us, these samples will be start by being saturated, and then they will dry out from the top, evaporation via evaporation on that the balance will be measuring the weight of The sample as it changes as water is lost, and from that it will collect, it will calculate, rather your water content, and it will also do your thermal conductivity as that sample dries. This is a great improvement over a lot of the previous methods that we would use. This gives you a lot of data points through that whole process, whereas before it was very hard to what we’d have to do is we’d have to take a sample, we’d saturate it, we’d take a reading with a thermal conductivity meter, and then we might put it in the oven for a little bit of time to dry it out partially. We’d let it come back to thermal equilibrium. We’d take another reading, and then we’d repeat this, 2, 3, 4 times to get some data points in there. This automatically does it for you, and it does that a much wider range of data points than just the two, three or four that you can get with the other methods where you’re doing it manually. This is all done using our LABROS SoilView Software. So it’s the same software that we use for the HYPROP and WP4C it all connects to the same one, and you can just set it up, let it run, and it does it for you. The VARIOS also automatically corrects the temperature drift that you might see for accurate results, the temperature drift before each measurement, there’s a a drift measurement taken, a temperature measurement taken to see if it’s stable. If it doesn’t meet a certain criteria, it’ll pause and wait a little bit longer for that to that reading to go, but then it’s also normalized so that you don’t have issues with your with your readings. I have a couple of images here for you to see also the insertion of that sensor. We have a tool that helps you insert it correctly into the soil, because the contact between that sensor and the soil are going to be very important to getting you good results. One of the things that we had seen when doing measurements with our other thermal conductivity sensors is that if the sensor is moved during insertion, it creates these gaps, which give you really bad data. So this installation tool was created so that you can slide that sensor into the sample in one fluid motion without the risk of having these gaps that would cause bad readings. The sample, or, I’m sorry, the sensor is then secured into the sample using these silicone retaining rings, so that there’s one on top, one on bottom, so that it’s held secure during that whole process. Down at the bottom there, we also should there’s a little diagram here that shows the transient line heat source method, which is what we use at the beginning there, there’s the gray section that says drift. That’s where it’s taking that measurement that we talked about and on our last slide, where it’s just double checking that everything’s stable. When you start a measurement, it’s going to automatically have a period of time built in for that sensor to come to thermal equilibrium with the sample. Usually, its default is set to 15 minutes you can change that to 30 minutes or an hour, depending on what your sensor, what your material might be you may need to increase that just to make sure that that temperature, the temperature of the sensor, comes fully into equilibrium with the temperature of the sample. If you if these are not in equilibrium, then your readings are going to be very skewed, especially those first ones. So it’s really critical to make sure that that that takes place after that initial drift period. There’s a measurement time where the beginning of the measurement happens, where the needle starts to heat up, and this is going to the interval of that’s going to change depending on how long you have your your measurement interval. You can adjust that in the in the VARIOS settings, but half of that time that you put for measurement interval is going to be the time period where the needle is heating up inside that the center of that needle, there is a heater, and there’s also a temperature sensor, so it’ll measure the temperature change as heat is applied, and then for the second half of that measurement, the heat is turned off, and it measures the change in temperature as that, as that sample starts to cool in that immediate vicinity of the needle. From this, we calculate the thermal conductivity of that soil at that moisture level at that certain point. This is repeated as long as that sample is running at a set interval that you that you determine you may want to change the interval if you have a soil that’s going to take longer to run. So generally, those some our sample lengths are going to go from, I’m sorry, our test links are going to go from maybe 4 or 5 days up to 10 to 12 days, depending on the soil sample. Particle size and porosity, are going to play a big role in that, because it’s going to affect that rate of evaporation. So you’ll you’ll be able to see real time data in the software as you’re doing this, so that you’ll be able to determine how long this is going to take, the data is automatically saved into our LABROS SoilView Software, and it’s automatically put into a file for you when it’s done. This is what that file is going to look like, these are your results here the top image is going to show you that raw data that we have, which is the detailed thermal conductivity readings that happens at every point. It’ll tell you your heater power temperature change, and it’ll show you that calculated thermal conductivity at that point. The bottom part is going to show you that weight and the change in weight as the evaporation takes place. And then on the bottom, this is the actual model that’s been fit to the to the curve. You can see on the bottom one that there’s different models selected. You can choose whichever one you want, and then hit that fitting button that’ll show up, and it will fit that data to that model and see how well it fits. And you might want to look at different models to see if it fits better to yours. One of the great things about this as well is that in the power user mode, you can also go in and and change some of this data. So if you have an outlier that you know is obviously wrong, because, for example, you bump the balance in the there’s one weight reading that’s just way off. You can actually go in and delete that point and delete the corresponding thermal conductivity point so that you can get clean data to actually get really, really great results and a better fit for that. And then the last thing here is just that we now also have a way to connect that HYPROP and the VARIOS together, because both the HYPROP and the VARIOS rely on evaporation methods to dry the soil sample these can take, as I said, several days to maybe a little over a week or week and a half running a separate HYPROP and a separate VARIOS sample can take a lot of time. You can now put these together and do the HYPROP and the VARIOS at the exact same time. So you can be measuring thermal conductivity, water content, get a soil moisture release curve, and get your unsaturated hydraulic conductivity all at the exact same time, and this is what it looks like together. You can see the the balance, and then the VARIOS unit, and then the HYPROP sitting on top, running both the thermal conductivity and the hydraulic conductivity at the same time. This can this can save you a lot of time if you’re running a lot of these samples, and it also gets rid of some uncertainty based on the difference between the sample when you’re running it on one machine versus the other, because you’re running them together in this one.

SHAUN WELDON 30:54
The VARIOS does conform to the ASTM Standard for thermal conductivity. We do have an app note on our website that talks about exactly how it complies, since the sensor is relies on the exact same principles as the TEMPOS, which is our handheld spot check, thermal conductivity meter, this this document works on that as well. The difference, though, is that the VARIOS currently does not conform to the IEEE standard for thermal resistivity, and this has to do with the sample size that is called out in the IEEE standard. The VARIOS in every other way, meets, but doesn’t meet with that sample size that’s called out thermal resistivity is going to be an option to choose for reporting on the VARIOS with the next version of our LABROS SoilView Software, which should be released here in the next month or so. And that’s all I have today. So if there are any questions I had to thank you all for coming and attending.

BRAD NEWBOLD 32:02
All right, thanks Shaun. So we’d like to use the next 10 minutes or so to take some questions from the audience. Thank you to everybody who’s already submitted some questions. There’s still plenty of time to submit them, and we’ll try to get to as many as we can before we finish. If we don’t get to your question live, we do have them recorded, and Shaun or one of our other METER experts will be able to respond directly to your question via the email that you registered with. All right, so looking at our questions today, our first one here, they’re asking about the the measurement time, and if there’s ways that they can speed up that measurement time so they’re not having to take measurements over the matter of a week or so?

SHAUN WELDON 32:48
Yeah, that’s that’s a great question. And we actually get this question quite a bit, because it does take some time. The best method for doing this is to put the entire unit, the balance and everything, into a compartment that you can put desiccant into, which will lower that ambient humidity and allow that evaporation to speed up a little bit. We often get people asking if you can put a fan on it, or put a heat lamp or something like that, to speed up that that evaporation, and we don’t recommend that, because it does cause a lot of vibration, which can cause noise in the readings. Putting a heat lamp, especially with the VARIOS, can be problematic, because you’re introducing other heat sources. And you know, the balance also doesn’t do really well with a direct heat source on it, because there’s expansion of the metals and things like that, and it causes a lot of variation, and especially in the weight readings. So the best method we’ve seen a lot of people put the entire system into like a glove box that you see in biological research labs, and then just put desiccant in there to lower that that humidity, and that does speed it up. With with some soils and samples, you can knock off a day or two with that. So that’s that’s what we recommend for that.

BRAD NEWBOLD 34:15
Awesome let’s see here, this next individual is asking if so you had mentioned there at the end that last slide, talking about the standards, and they’re asking about sample sizes, and can they use different sample sizes, or does it have to be that using the official sample ring that comes with the instrument?

SHAUN WELDON 34:42
Yeah so in the software, there is an option to use a custom sample size. Basically, there’s an option, it’ll says the 250 milliliter ring, or you can do custom. And when you do custom, it will ask you for the surface area of the sample and then the height of the sample so it will use that then to calculate the water content. There are a couple of considerations, though, the biggest one is the weight limit of the balance. So the balance will only take 2.2 kilos, which is a little over what’s almost five pounds. So if you have a large if you have a sample of something that’s very dense that you’re trying to measure, then that might be over that weight limit. If you have a larger sample, you also need to make sure the other consideration is that you have enough material to get the needle all the way in. If you have that needle sticking out, either on the far end or on the close end, at any point, you’re not going to get as accurate or readings, because you’re not going to be in the center of that of that sample.

BRAD NEWBOLD 35:52
All right, good to know. This is a question that we’ve had with other instruments as well, is can you use the VARIOS in the field, as opposed to in the lab, or it being able to do both, but primarily they’re asking about using the VARIOS in the field?

SHAUN WELDON 36:10
So using it in the field is usually problematic. We have had a couple of people that have kind of a field shed that’s that’s somewhat climate controlled, and you can use that. You can use it in that kind of instance, but the biggest issues that you’re going to run into using it in the field are climate stability. So if you have, for example, you’re running it for a couple of days, if you have large temperature swings between day and night, it’s going to cause a lot of variation in those readings, which can cause problems. The second thing is that that balance needs to be level to take the to take accurate weight readings. So if you are trying to use it in a place that doesn’t have, you know, a sturdy level table, that can cause some problems with the readings. And then, I guess. The third thing is that the balance itself does require a power source, a stable power source, because we are heating things up. It needs that full it doesn’t work well with a battery normally, and there’s no real interface for the balance, for the balance of the battery, as is, you’d have to do some heavy modifications, which voids warranties and can cause other electrical problems.

BRAD NEWBOLD 37:24
All right, this next question they’re asking, does the sample need to be a virgin undisturbed sample, or does it need screening?

SHAUN WELDON 37:34
So this is a great question. Normally, what we recommend is trying to use as close of a sample to what you’re trying to measure in the field. This can be tricky. If you have a very cobbly soil, obviously that’s not going to that’s not going to work very well with trying to insert a needle into it. So if you have soils that have large stones or cobbles, you can remove those and just and just repack it to the density that you that you might have had naturally. There are also some materials that are just not going to be able to you’re not going to be able to collect in the in the the ring, trying to collect sandy soils with these is is a pain because it just doesn’t stay in the soil in the ring. So in those cases, you’re going to have to repack it. You can’t do the undisturbed method. And so what we recommend, in that case, is trying to know that density, that bulk density of the soil, and repack it as closely as you can in the ring.

BRAD NEWBOLD 38:36
I guess, similarly to that you had mentioned, you’ve mainly talked about working with soils. Can you talk a little bit about working with non soil materials? You’d mentioned insulation and other things along those lines?

SHAUN WELDON 38:50
Yeah, absolutely. So we have a lot of people that have used the VARIOS as well in materials that are not, are not soil. They’ve used them in some, you know, poured synthetic materials, plastics and things like that. We’ve had some people use them with with poured concretes or stone or things like that as well, which you can you can do those harder materials are going to need a pilot hole drilled. We do have the specifications for what kind of pilot hole you’d need to drill, and then you’re going to want to use some kind of thermal grease just to make sure that you’re maintaining that good contact. Like we said before, that’s that’s probably the most important part of a good thermal measurement is contact between the sensor and the materials. So those are going to be the things that you’re really going to want to pay attention to when you’re using other materials.

BRAD NEWBOLD 39:50
All right, we’re getting close to the end of our time here there. There was a another question, asking about frozen samples that would go into that same same consideration with drilling pilot holes and, thermal grease. There are a couple questions asking about the temperature sensor itself, can you describe you know how it works? Is it a single needle, dual needle, those kinds of considerations there?

SHAUN WELDON 40:12
Yeah. So the sensor, the temperature sensor, is a thermistor that’s in the in the needle there, it’s in center, inserted into there. It’s encapsulated in thermal epoxy, but it’s in, it’s in the center of that needle there. So when you’re using this, this sensor, you want to be really careful with not bending that needle, making sure that you’re being really careful with the cables as well, so you’re not bending them sharply. You’re not causing, you’re not causing any kind of damage to those cables, because that will affect the readings of that. But as long as you’re, you know, taking care of that, making sure it’s not getting bent any weird directions, that those needles, they last for a really, really long time.

BRAD NEWBOLD 40:59
And with that, so with the transient, was a transient-line heat source so it’s, it’s the two needles it’s sending heat up the one and measuring with the other one is that how it’s working?

SHAUN WELDON 41:12
No, so the VARIOS is only single needle. Sorry, yeah, I should have mentioned that earlier. Yeah, the VARIOS is only a single needle so the both the heater and the temperature sensor are both in the same needle.

BRAD NEWBOLD 41:24
Thank you for that clarification. All right, I think our final question here, and then we are going to wrap up. Thank you again for for everybody who has submitted questions. Again, if we did not get to your question, we do have them recorded, and Shaun or somebody else from our METER team will be able to you to to answer those. The, the final question here is, I guess, what are, what are some of the and there have been a couple questions here. We don’t want to turn this into a sales discussion here, but why would somebody choose the VARIOS over a potential other competitor or a another product line from from a different instrument provider?

SHAUN WELDON 42:07
Yeah, that’s a great question. At the moment, there isn’t really another instrument out there that does the full thermal dry out curves like we do. Most of the other methods that people are using are those, the ones that we kind of discussed earlier, where you’d take the sample. You take the initial reading when it’s saturated, dry it out a little bit in an oven. Then you have to wait for it to come back to to the same temperature as the room. Take the other reading, and then just repeat that, however many times you want. The great thing about the VARIOS is you do that initial saturation, you put it in there, and then you determine how long, how often it’s going to measure. So you’re not just getting those four, five points. You’re getting hundreds of points as it goes through and creates this curve. And with some soils in particular, there are different behaviors that you might see with that thermal conductivity as they dry. We have a couple of sample files included where you can see some of that behavior with different soil types, with sand versus clay versus silt, so you can see that and you really capture that different behavior with these.

BRAD NEWBOLD 43:18
All right, that’s going to wrap it up for us today. Thank you everybody for joining us. We hope that you enjoyed this discussion as much as we did, and thank you again for such great questions. Please consider answering the short survey that will appear after the webinar is finished, just to let us know what types of webinars you’d like to see in the future. And for more information on what you’ve seen today, please visit us at metergroup.com. Finally, look for the recording of today’s presentation in your email, and stay tuned for future METER webinars. Thanks again, stay safe and have a great day.