The Liquiphant FTL51B, FTL62 and FTL64 vibratory slide level detectors, equipped with Hart electronics, make it possible to remotely test Heartbeat Verification and Sil.
While many process transmitters today have advanced features, such as diagnostics, functional tests, modern communications, etc., there are still a few types of sensors, such as level sensors, that do not benefit from all these features.
This imposes constraints, sometimes heavy and expensive, on technicians and field workers when they have to check the proper functioning of a level detector mounted on a large tank and likely to have a problem, for example.
Endress+Hauser now offers 8/16 mA electronics with Hart digital protocol for its Liquiphant vibrating slide level detectors FTL51B, FTL62 and FTL64, which succeeded the Liquiphant FTL50/51, FTL51C and FTL70/71 respectively two years ago. "This new electronics unlocks new features. Customers can choose between two operating modes: a switching mode (8/16 mA) for conventional level sensing and a 4/20mA mode proportional to the vibration frequency of the blades," says Andréa Logos, Head of Chemicals at Endress+Hauser France.
The FTL51B, FTL62 and FTL64 Liquiphant level detectors thus become true standard 4-20 mA sensors, capable of reporting a primary value (in this case, the frequency of the vibrating blades) to a PLC. One application now made possible is to differentiate between two products with very different vibration frequencies. "In addition to the level detection information itself, the customer will be able to know, in the case of a biphasic medium, whether the sensor is located in the gaseous sky of the tank, in the first phase of mixing or in the second phase," explains Andréa Logos.
Heartbeat Technology's combination with the Hart protocol also makes it possible to define thresholds for detecting the level and changing the frequency of the signal over time. "Exceeding custom thresholds, and therefore sending alerts, can result in fouling or corrosion of vibrating blades, or a drop in resistance at the current loop. This is the role of Heartbeat Monitoring: to continuously monitor certain parameters to quickly identify a possible problem, before the device fails," explains Aurélia Genet, Team Leader Process Industries at Endress+Hauser France.
Another advantage of the new electronics is the ability for operators to remotely perform Heartbeat Verification and SIL tests according to IEC 61508 and IEC 61511. "It was already possible, with the FTL51B, FTL62 and FTL64 Liquiphant detectors, to trigger tests locally, via the Bluetooth interface and a tablet or smartphone with the SmartBlue iOS/Android app. But it is now possible to do this via the Hart signal, from an example of supervision," says Andréa Logos.
Users thus have the tools to have a real view of the health status of their level detectors and, ultimately, to know what is happening inside their tanks and processes. They no longer have to wait for a device to be defective to intervene and can plan the most appropriate action based on the information reported by the device. Since they no longer need to disassemble the device to do these tests, operators are no longer obliged to climb to the top of a tank, to plan the installation of a ladder, or even a basket, or to empty a tank. This represents significant time savings for maintenance teams.
The three vibratory blade level detectors for liquids each meet a well-defined type of application:
- Standard model Liquiphant FTL51B: process temperature from -50 to +150 °C (PN 64 or 100 bar version optional)
- FTL62 Liquiphant model with highly corrosion-resistant coating (ECTFE, PFA or enamel): process temperature from -50 to +150 °C and process pressure from -1 to 25 or 40 bar (depending on coating)
- High temperature model Liquiphant FTL64: process temperature from -60 to +230 °C and maximum pressure up to 100 bar