Industrial safety is driven by many different reasons, but when it comes to level measurement the catalyst for increased safety measures is clear. In the days before radar, oil tankers and onshore storage tanks suffered a lot of severe accidents. Unfortunately, the older, mechanical way to measure tank levels and guard against detrimental spills wasn’t quite up to the task.
“In the old days, it was common that the measurement instruments failed and thus jeopardized the safety,” says Ingemar Serneby, solutions manager at Emerson.
As the industry turned to radar, the opportunity to enhance safety and diagnostics capabilities increased. It also made safety and diagnostic procedures more efficient.
When the primary technology consisted of mechanical instruments such as floats, users had to go out in the field and pull up the mechanical devices to make sure that they did work. With today’s radar technology, the level devices continuously test themselves. “For instance, our guided wave radar can be equipped with a reference reflector on the wire,” Serneby says. “Guided wave radar uses a wire to measure the level inside the vessel. By having a reference reflector in the vapor space where you shouldn’t have anything normally to measure, obviously at very high level, the reference reflector can trigger the instrument to measure it or to avoid it.
“This is just a very, very tiny echo generated by it. But by triggering it to measure it, we measure a physical target in the tank environment and that will serve as as a comprehensive proof-test,” he continues. “So, in that case, all that mechanical work that you had to do previously, to go out there, climb a tank, bring a bucket, lower the float down there, see if it floats, if it alarms, it’s done from the control room. That is a big help for the user.”
Essential efficiency
Such efficiency is paramount as operators aim to maintain their proper safety integrity levels (SIL). “You have to assess your safety loop and see what kind of integrity level is valid for your operation,” Serneby says of the continuous process. “The safety loop consists of different things like a level device, a temperature sensor, a pressure sensor, an actuator, a valve. To be within that safety level, you have to make sure that you maintain this level throughout the lifespan of the equipment. So, what happens is that you have an expected time until failures occur, and to ensure that you are not on the wrong side, you have to make proof tests.”
He adds that frequent proof tests mean users can maintain their integrity level. The proof test ensures being at the right integrity level that is valid for the entire loop. The weakest part of the loop defines when it’s time to do the proof tests, and to know when it’s time to perform the proof test, users have several data points regarding the instruments and that’s where the standards come into play.
Emerson’s radar products have evolved to meet the needs of continuous safety monitoring in level measurement applications.
Connectivity and diagnostics
“I would say that connectivity and diagnostics go hand-in-hand,” says Mikael Inglund, manager product management software for Emerson. “If you don’t have any connectivity, you don’t get the information you need.”
When Emerson introduced radar as a level measurement technology, the industry was mainly using conventional 4-20 mA current loop as connectivity to other systems. It limited data transfer to the measured level and some basic device diagnostics.
“However, using only the measured level can provide proactive diagnostic and maintenance solutions. Our floating roof monitoring solution, which analyzes the roof movement by tracking three or more level transmitters measuring on the roof,” Inglund says. “If the tank roof tilts or does not move smoothly it will provide early warnings in order to avoid any serious accidents.”
“When digital HART communication was introduced it enabled a new way of connectivity and allowed much more data to be transmitted,” Inglund says.
“That gave us the opportunity to develop advanced software features and the RadarMaster+ configuration tool, which drastically enhanced ease of use and enabled new powerful diagnostics. For example our Smart Meter Verification, which performs advanced integrity and self-diagnostic checks and provides a health report,” he continues. HART connectivity also enabled other features such as Signal Quality Metrics (SQM) for probe clogging detection, Power Advisory for monitoring proper power supply, guided remote proof test for functional safety and much more
The introduction of WirelessHART and Bluetooth added connectivity to level devices installed in locations previously difficult to reach, allowing for safer operation and configuration, but also added new applications and devices to Emerson’s PlantWeb Digital Ecosystem.
Connectivity is all about the device’s ability to connect into systems and to provide data to software applications, enabling advanced diagnostics and process insights. New connectivity standards such as the emerging Ethernet-APL will enable exciting solutions within cloud, built-in AI, virtual instrumented networks and much more.
Emerson is continuing to build upon its technology for the future. “By adding powerful electronics and high bandwidth connectivity, we will see data driven intelligence and advanced features moving into the level transmitter, making it even more intelligent and cybersecure,” Inglund says.
