Excellent process control requires accurate measurements, a robust control strategy, and precise final elements such as control valves, actuators and regulators. Measurement instrumentation is an essential consideration.
In this Emerson Automation Experts podcast, Emerson’s John van Gorsel joins me to discuss these considerations in pressure and other measurements. Technology advancements have enabled new capabilities and simplified configuration, operation, and ongoing maintenance.
Give the podcast a listen and visit the Pressure Measurement and Measurement Instrumentation sections on Emerson.com.
Jim: Hi, everyone. I’m Jim Cahill with another “Emerson Automation Experts” podcast. Accurate and reliable pressure measurement is crucial in a broad range of chemical industry applications, and safety is truly a life-or-death issue due to the presence of toxic, flammable, and potentially explosive products.
I’m joined today by Emerson’s John van Gorsel to discuss some of these challenges. John is the product manager for Pressure Solutions in Europe and will share how the latest instrumentation functionality minimizes installation and operating costs and increases reliability, efficiency, and safety in chemical industry applications. Welcome, John.
John: Well, thank you, Jim. It’s a pleasure to be here.
Jim: Well, I’m so thankful that you’re here. Well, why don’t we start out by asking you if you can share a bit of your background with our listeners?
John: Yes, my background is electrical engineering and I started working for Emerson in 1986 as an inside sales engineer for the measurement products. I did it for a couple of years. I moved into an outside sales role. And in the early ’90s, I moved into a product support role for various measurement products. It was pressure, temperature, it was wireless, it was level.
The key thing in that period, which I did that for 25 years almost, was helping customers to solve problems. In 2015, I moved to the European role as a product manager for Europe, and now I would almost say I’m still heavily involved in helping customers solving applications and challenges. Now I work with a larger team of technical specialists and product managers in the countries.
Jim: Now here I thought I was a long-timer with Emerson, starting in ’88, but I guess you got me beat there. Can you highlight some of the changes and challenges in the chemical industry?
John: Yes, absolutely. I think at the moment, one of the key things that we see is that the chemical industry is moving towards a life cycle approach. We’ve seen this discussion on the Plastic Soup and the microplastics and the PFAS. We see that chemical companies are now focusing on the full cycle. In their design of chemicals, they take the raw materials into consideration, the energy used, but also the recycling. We see that that poses some challenges on the technology that we have.
And especially, as an example, the recycling that we now see happening, the advanced recycling really pushes the envelope of what we can do with the instrumentation in terms of high temperatures and high pressures and vacuum pressures. That is what we see where the chemical industry already started to spend a lot of effort in energy efficiency, reducing their energy use. We now see that they are moving towards electrification of processes, the use of hydrogen or biomass, geothermal energy, and that all will require new technologies to adapt to those new circumstances.
Now, if I would mention that what I see as the biggest challenge that we see in the chemical industry is defined skilled personnel. This is partly due to the aging of the workforce, the graying of the workforce, but we also see in Europe that in some countries, there’s still a reduced number of people moving into technical studies. The challenge is to get that personnel into the chemical industry.
I probably should mention as well that we still see that there is a little bit of an assumption that working in the chemical industry you get dirty hands and that stops people from going in that direction.
The one thing that chemical customers are doing at the moment, what the chemical industry is doing is making the chemical industry a better place to work by making tasks easier. A very important one. There is, for instance, to make sure that you don’t need to spend too much time inside the actual installation. People don’t always realize that to safely work in a chemical factory you need protection equipment, PPEs. And believe me, I’ve been there when you have to work inside a plant wearing these flame-retardant overalls, safety shoes, safety gloves, safety helmet, mufflers, safety goggles. It’s pretty tough to work under these circumstances.
So if you want to make a chemical plant a better place to work, the one thing you should try is to reduce the time that people actually need to work inside that plant. Now, what we see as a result of that is that we see requests for simpler instrumentation, easier to understand, reducing the time that you need in the plant, in the fields to configure these instruments.
Jim: Well, that sounds like a number of changes and challenges from some of the regulations that are ever evolving to, yes, that demographic challenge of a lot of us reaching the end of our working lives, and technology can play a role in that. So I guess, how does the new technology meet these challenges in chemical processes?
John: Yeah, I want to explain that. I think it’s best to split it up into two categories. On one hand, we added several features and technologies to address specific issues that we know of. And on the other hand, we make the everyday tasks that you need to do with instrumentation easier. If I start with that, the latter, if I start with that making things easier, for instance, on our 3051 series of pressure transmitters, we gave that transmitter an upgrade and now it can have a graphical backlit display.
And this is a big step forward from the legacy segmented display because a graphical display backlit is easier to read under all circumstances, but it also allows us, for instance, to show more information by showing, as an example, the icons that we may know from the NAMUR NE 107. So an icon indicating what the condition of an instrument is. That was never possible on the legacy displays.
In addition, the display also supports multiple languages. So we can set it to Spanish, to German, to Italian. So that is the outside of the instrument. But in the configuration, we also made some improvements in the user interface. One example, there is a lot of pressure transmitters are used for a secondary function. Think of flow, think of level. And to configure an instrument, for instance, for flow, you need to set certain parameters. You need to set the square root function. You need to maybe set the units in cubic meters per hour or liters per second.
To make that easier, we grouped all that information onto a single page. That reduces the risk of making mistakes or forgetting certain parameters, and it makes it much more easy for the person that is configuring the instrument to do this, saving a lot of time.
What also should be mentioned is that we added Bluetooth configuration or Bluetooth communication to the instrument. Bluetooth communication is a short-range communication that allows a maintenance person or an engineer to look at the condition of an instrument, to configure the instrument, to make changes in the configuration without having to physically open the instrument or climb towards the instrument. It reduces the time. It also makes it possible to do maintenance tasks without opening the instrument, so without having to power down the instrument. In general, it reduces the time that people need to be in the plant. It reduces the time that people need to be working at a certain height. That is a big step forward.
In terms of additional functionality to address specific problems, we added some diagnostics to the instrument. Plug line diagnostics is one example, but we also have loop integrity diagnostics. Both of these diagnostics address specific problems that we see in the chemical industry, being the clogging of impulse lines. You’ll lose your measurement because the impulse line is freezing up or clogging with dust. And the power diagnostics monitor the condition of the power supply or the power to the instrument. Faulty wiring, corrosion of terminals, etc., is detected by the diagnostics. And we added guided proof-testing to the instrument that help maintain a safety system.
Jim: Yeah, so that sounds like improvements in the local display there with the backlighting and organizing the tasks people need to do through the user interface and everything, are steps along the way to making it easier for them to work with and addressing the skills challenges that you brought up earlier.
Now, you mentioned proof-testing these instruments, which I know is required when they are deployed in safety instrumented systems or SIS. These can be quite a complicated, laborious, and time-consuming task. Can you elaborate a little more on why this is so?
John: Yes, it’s probably good to explain a little bit on how the instruments are selected or how safety instrumented system is designed. It’s all about the risk that you have in an installation and you try to mitigate or to reduce that risk in the engineering phase or in the design phase by, for instance, changing the hardware of the design, changing the rating of certain components, keeping people away. That all reduces the risk. But there is a certain risk that remains and you need to solve that, you need to mitigate that with a safety function, a safety instrumented function.
Now, the way that the safety works is that based on the level of risk that the process has, there is a certain requirement for the safety function. We allow the safety function to fail a certain amount of times and you have to think then that when you have a certain risk from the process, we allow the safety function to fail once every 10,000 years. So that is a little bit of what you should think about. But that is based on the reliability of the components that you use in that safety function.
Now, when you design that safety function, you can look up all those failure rates from the instruments and you have the failure rate at that day. But how can you maintain that failure rate? How can you know that after a year in bad weather and changing conditions and a vibrating environment etc., that it still has the same reliability and that there are no hidden errors somewhere in that system? And that is why you need to do proof-testing on the instruments.
If you do a proof test, what you actually do is you test the instrument for hidden failures. And hidden failures are failures that may affect the output of the transmitter, so the functioning of the transmitter, but it’s not detected by the normal safety system. It’s not detected while the instrument is in use. So you do an additional test and that additional test will reveal a certain amount of the possible failures in the instrument.
Now, we as Emerson created the procedures for our instruments and we used a third party to help us with that. So we tell exactly what you need to do to test the instrument. Now, imagine what happens when you have a lot of instruments installed and all these instruments may have a different procedure to do the proof-testing. You need to follow that proof-test that is recommended by the supplier because otherwise, you don’t know how that test will reveal failures.
So we have a documented procedure. And now when you do the proof test on a certain instrument, you have to find that procedure. You need to find the right manual. You need to verify that that manual is actually valid for that revision of the instrument. So we thought, well, this could be easier if we store that information in the instrument or in the device description, the device driver. So now if someone wants to do a proof test or needs to do a proof test, the tool that he or she uses will tell exactly what steps to take.
And when the test is done, where you know exactly that you did the right test, it will also store the result of that test in the form of fail or pass in the transmitter. So you can always see when the test was done and what the result of that test was.
So the 3051 with guided proof-testing saves you a lot of hassle in finding the right documentation. So it reduces the potential errors that you make by using the wrong procedure. So it’s easier to keep your safety system within the tolerable limits.
Jim: Yeah, that sounds like instead of hunting down manuals to see what you need to do with that stored in the instrument, and basically tells you and guides you through the process. Yeah, I can see that being huge time savings when it comes around to proof-testing all those instruments.
Now you had mentioned diagnostics, the built-in diagnostics. I’ve heard some about the changes in diagnostics. So can you tell us some more about this?
John: Yes, absolutely. I think there were several changes that we’ve seen with diagnostics. In the initial versions of instruments, when instruments became smart, the diagnostics were all around the health of the instrument. So the diagnostics would check, is the instrument still working within its parameters? Is it still good, or did it fail?
At a certain moment, we realized that we could do a lot more with the instruments, that we could actually help customers to identify issues with that process rather than only with the instruments. And the current transmitters, the current 3051 that we have has a couple of these diagnostics. So it does have the self-diagnostics that tell you that the instrument is still functioning well.
But it also has what we call process alerts. Process alerts are alerts that an operator or an engineer can set in the instrument completely separate from the primary 4 to 20-milliamp signal. So it’s not interfering with the control loop at all. But you can set some process alerts where you can monitor if the pressure is above or below certain thresholds. And when the pressure comes above that threshold, it writes it in the log. So afterwards, you can look in the instrument and see, hey, I’ve seen that the pressure was five times above the limit that I set or the alert limits that I set where it was below that pressure. So it gives you an opportunity to do some root cause analysis when there is an issue with the installation.
We cannot do this only on the pressure. We can also do that with the temperature sensor that is in the pressure sensor. So we have a pressure or a temperature sensor in there. We use that for compensation. But you can use that as well. And there you can see that maybe the temperature of the transmitter was high for a certain amount of time, or it was low with the risk of freezing of the impulse lines, for instance. So that is an added diagnostics that tell you a little bit about the surroundings of the transmitter rather than the functioning of the transmitter itself.
Some other diagnostics that we have. One was already available for a while in the 3051 series of transmitters is the loop integrity diagnostics. The one critical thing with 4 to 20-milliamp instruments is that the whole loop is a milliamp signal that goes through that loop. And the advantage is that if there is a voltage drop somewhere because of issues in the line or whatever, it doesn’t affect that milliamp signal going in that loop. And that is a big advantage.
Now, the challenge is that when there is too much resistance in that loop, or there is a leak current, at a certain moment, you may see issues with the measurements. A transmitter needs to have a certain voltage at its terminals to operate. Once the voltage is below that limit, which is typically between 10 and 12 volts, when it comes below that minimum voltage, the transmitter will stop working. So you lose your measurements. The diagnostics will tell you well in advance that the voltage is becoming too low. And the voltage becomes lower when there is, for instance, corrosion or moisture in the terminals. So it’s warning for a situation that could potentially make you lose your measurements.
And the second of the advanced diagnostics is the plug line diagnostics. And this is completely new for the 3051. It’s a technology that we already used for something like 15 or 16 years in a different transmitter. And we now have it implemented in the 3051. And what we do, well, if I simplify it, then I would say we use the pressure sensor as a microphone.
And I once made a comparison that I said, “Well, we’re actually mimicking what the older engineers did.” They listened to the process and they said, “Well, hey, I listened and I hear that there is something wrong in the process. There is a valve cavitating,” or, “A pump is losing its bearings.” And we do the same with the pressure sensor. We listen to the noise of the process and that noise of the process will change if something happens in the process.
So there is a certain almost like a fingerprint noise of the process. And when that changes, we know that the impulse lines are clogging, for instance, because that will give a damping on that noise. And it’s a very powerful type of diagnostics because it warns you that you’re about to get a problem with your measurement. But it warns you before the actual problem occurs. So that makes it a very useful addition for situations where there is a risk of clogging and losing the measurement.
Jim: That’s so interesting how technology has advanced where it’s not just looking internally to itself, how are all the components and the transmitter doing, but look externally at the process like some of those examples you gave and the electrical side of things of what you’re doing to power it up, all the things that could spot problems. Maybe the device itself is fine, but there’s issues outside. So that’s very powerful diagnostics there.
John: Yes, it is.
Jim: Now, I know differential pressure level measurement is used in many chemical process applications. What are some of the benefits of using electronic remote sensor-based DP level measurement?
John: Yeah, that’s really a very good question, Jim. And I do need to go back in time a little bit to explain this because this is something that the whole development took decades to happen. Differential pressure transmitters have always been used for level measurements. And the reasons are, it’s simple. Everyone understands how a pressure transmitter works and it’s easy to calibrate, etc. And any liquid in a vertical column, the weight of that liquid will generate the pressure. So when you measure that pressure, you can find out what the level is. So it’s a simple, straightforward measurement with a few exceptions, but it will always work.
Now, there are some measurement challenges, and one of the challenges is when you have a tank that is pressurized, so it’s not connected to the vapor, the vapor space is not connected to the atmosphere, you need to compensate for that pressure that is present in the tank. And the easiest way to do that is you have a pressure transmitter, you mount it to the bottom of the tank and you connect the reference side, the low-pressure side of that pressure transmitter, that differential pressure transmitter, all the way to the top with an impulse pipe and you connect it there.
Now, in some applications that works, but in a lot of applications, what happens there is that you still have some evaporation from the process, it condensates in the impulse line, and over time you get liquid in that impulse line, and that gives you a measurement error. So you need to train it, so that means you have additional maintenance work on that tank.
Then someone very clever came with the idea of what if we already fill up that impulse line so that we already have liquid so we don’t have an issue with the condensation. That works, but you need to make sure that the liquid is always at the same level. So you need to control the level, and that’s also another maintenance task. Someone needs to climb up to the top of the tank and check the level in that impulse line.
And there are some other issues as well, even apart from the fact that making an installation with impulse lines is very expensive because it’s a lot of work. It’s sometimes complicated work too, what you do, you need a specialist to do it. But the fill fluid that was used in those wet lag systems, as we call them, is usually glycol and that’s slightly hygroscopic, so over time it will pollute with water, it changes the density, etc.
The most common solution to all of this is the use of remote seals. A remote seal is a capillary connection, a capillary of a certain length connected to the transmitter, and then an external additional diaphragm. The transmitter is mounted to the bottom of the tank and the capillary runs all the way to the top of the tank and there we connect a reference site. Now, a capillary filled with a certain fluid will create issues when the temperature changes, so that fill fluid will expand, it will contract, it will change the pressure.
One bright idea was what if we have exactly the same capillary on the high and the low-pressure side? Because that will cancel out the effects on both sides. That works to a certain level, but there is still an effect that is called the head effect and that has to do with the vertical distance on the low-pressure side. So if the temperature changes, you still have an effect. And just to give you a number, in a normal-level application, that effect will probably give you a 5% error on the measurement.
And the other thing, and I haven’t even mentioned that, is that when you have a transmitter with two remote seals, and I know a lot of people will recognize this, where a standard transmitter is something like 2, 3 kilograms, one person can pick it up and go into the plant, install it, etc. A transmitter with two remote seals can… First of all, the remote seals are supposed to be flexible, but it’s bendable at most. So it’s really a tough construction. You need two people to carry that. It can be 25 to 35 kilograms depending on the types of remote seals. So you need two people to install it.
Can you imagine how it is if you need to climb up a tank to install such an instrument? So it’s a lot of work. You need a lot of safety measures in addition to what you normally do. You probably need scaffolding.
So we got this question, is there a possibility to do these measurements, but then electronically? So have the two seals so we don’t have the issues with the dry and wet leg systems, but have the measurement at the top of the tank and at the bottom of the tank, but not all the disadvantages of the capillaries. So we designed what we call the Rosemount 3051S Electronic Remote Sensors. So instead of having a capillary, now you have two separate sensors where one is the master, one is the slave, and the master calculates the differential pressure, but we only connect these two sensors with a four-wire electrical connection.
So one person can install it, can install one sensor, run the cable down, connect it to the second sensor at the bottom of the tank, and you have a very accurate measurement not affected by temperature changes. And the main thing is that it’s much, much easier to install with less time needed at height. You don’t need to climb with a very awkward construction. So the electronic remote sensors really solved big problems that we saw in the chemical industry. The applications where we see it, everything of more than 3-meter height there is already an advantage.
Now, think of distillation columns. They can be 30, 40 meters high. If you want to cover that distance with a standard transmitter, with capillaries, capillaries, in reality, you cannot make them longer than 10 meters. That’s more of a practical limit. So you need to find a different solution. When you look at electronic remote sensors, we could put them 100 meters apart if needed. We can have more than 100 meters of electrical cable between the sensors. So we’re not limited at all there. So it’s a big change and it solves a lot of the disadvantages that were traditionally connected to differential pressure level measurements.
Jim: Yeah, it sounds like the installation challenges we’re able to overcome, as well as the accuracy of that electronic connection between the sensors sounds like a great solution for many applications in chemical processes.
Now, I know pressure gauge applications are another thing commonly seen for local visual display within the process. Can you share some of the innovations in this area, such as Rosemount Wireless Pressure Gauges?
John: Yes, I can. The Wireless Pressure Gauge, it all started with customers coming to us and explaining some of the challenges that they saw with gauges. A gauge is usually a mechanical device and it’s based on what is called a Bourdon tube. And a Bourdon tube is really a hollow tube, elliptical tube, slightly bent. And when you pressure on it, then it will stretch and that movement is used to drive a needle on the dial.
And the big advantage there is that it’s a mechanical device. And so it gets damaged pretty easy. It is not protected against overpressure. Now, the big risk that customers also see is that when there is a leak, that Bourdon tube… So the process is behind the dial, meaning that the operator that is looking at the dial of a mechanical pressure gauge is almost looking at the process.
So right behind the dial is the process pressure. So whenever you have a risk of these gauges failing, then you need to take other measures to protect the gauge by adding a remote seal, for instance. By the way, all the mechanical gauges have a plug on the backside that if there is a pressure buildup, that it can blow in the opposite direction away from the operator.
So gauges fail quite often. Metal fatigue, they’re not very good in dealing with overpressure. They’re not very good in dealing with vibration, for instance. And the one thing that I remembered is that customer was really concerned. He said, “Well, if that gauge says 0, and I want to do an operation, I want to start a pump, gauge says 0, how do I know if it’s really 0, if there’s really no pressure or that gauge failed?”
And when we heard that, we thought, “Well, we need to design something else. We need to go back to the drawing board and not try to make a better gauge but use a different design.” So we started with a pressure sensor, the one that we already know because a lot of what we do is based on pressure sensors. And we made the gauge electronic and electronic in a way that it’s battery-powered but it will work for 10 years or more. Because we use a separate pressure sensor, it’s protected against overpressure because this pressure sensor that we use can deal with up to 150 times the pressure that is present in the process. So there’s no risk of leakages or an overpressure incident.
The other thing that we solved with this solution to pressure gauge application is that the dial that we have, the needle that we have is driven by a stepper motor. When you see a traditional gauge on a vibrating application, you see that needle moving up and down and it’s just a gray area where that needle is somewhere. When you see the gauge that we have, the needle is perfectly still indicating the right pressure. And if there is a failure, you will see it because there is an LED indicating the condition of the instrument. So we solved a number of the big problems that customers have.
And in addition, we added the WirelessHART communication to the Wireless Pressure Gauge. So that gives an additional possibility of reading both the measured value, but also the condition of that gauge in a central location. Or you can use it to strengthen a network if it’s already there.
Jim: Well, that sounds like it solves issues around potential safety problems. And then adding the WirelessHART component, you’d be able to get that remote reading in addition to the local one you’d get through the display there. So that’s really, I think, valuable for a lot of the applications there.
Well, John, this has been a really great discussion. Can you kind of summarize for our listeners some of the key takeaways from our conversation?
John: Yes, I can try to do that. So we heard that the chemical industry has several challenges and these challenges are all around, how do I keep my plant safe? And how can I reduce the amount of time and effort that is needed to keep a plant safe? And we also heard that the chemical industry is sometimes struggling with the complexity of instruments and they need simpler instruments that are more user-friendly. And we designed and improved some of our instruments to address specifically these challenges that the chemical industry have. And we also have some advanced solutions like the Wireless Pressure Gauge and electronic remote sensors that address specific challenges that exist in the chemical industry.
Jim: That’s a great summary of things. And I guess to close things out, where can our listeners go to learn more about some of these things we’ve discussed?
John: Well, I would suggest to use our website, emerson.com. And you could even use rosemount.com, and you can use the search function for 3051, and it takes you to multiple pages with information, including an interactive 3D animation of the instrument where you can test all the features that it has. Or you can search for the 3051S ERS or Wireless Pressure Gauge to go to the respective pages of these products. And you’ll find a lot of information, documentation, manuals, user experience with these technologies, information about applications, etc.
Jim: And I know for some of the things that you mentioned along the way, I’ll add hyperlinks in the transcript, make it easier to get to some of those. Well, John, thank you so much for sharing your expertise with our listeners today.
John: It was a pleasure. Thank you, Jim.
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