Process and Device Diagnosis
Modern Flow Meters Also Monitor The Immediate Process Environment
Less Is More
Even today, there are a great many things that can be done to facilitate fault detection and troubleshooting for operating and maintenance personnel in the event of a fault. “Corrosion or coatings that could result in changes to the end product are already reliably detected and signaled with Coriolis mass flow meters. Vortex meters, too, are able to identify and detect them,” adds Walter Staudt, Manager Business Development Flow Solutions at Yokogawa Germany. And in its RAMC rotameters, for instance, Yokogawa also supplies a patented suspended solid-particle detection system, while the ADMAG magnetic inductive flow meters can recognize coatings and the vortex flow meters can detect production controls.
Where the media to be measured are difficult (abrasive, corrosive, deposit-forming), diagnostic functions can be used to detect changes in the measuring system at an early stage. For Endress+Hauser devices, this is covered by the Advanced Diagnostic add-on software, which can be retro-installed for every device. Recording selected process and device parameters such as mass, density, temperature or pipe damping allows comparison with prescribed reference values.
Each of these diagnostic parameters can already be assigned a freely adjustable limit which, if violated upwards or downwards, will result in an immediate warning message being output. “Such limit value functions not only make it easier to plan the maintenance intervals, but also facilitate the real-time exchange of devices in critical applications or for essential cleaning cycles,” says Dietrich when describing the additional benefits.
The user normally profits as soon as the extensive diagnostic functions are implemented. ABB flow measurement technology, for instance, includes a grounding check that assesses the quality of the connection to ground and reveals possible sources of faults.
In addition, insulating or conductive coatings on the inside wall of the pipe have an effect on the precision of measurement. A trend record of the coatings can be taken to ensure better control over a specified period of time and hence a consistent product quality and measuring precision. “This makes maintenance plannable and avoids sudden down times,” according to Giebhain-Wagner.
Simple Handling Of Information
At ABB, the emphasis is on the ease of handling the information. Whatever the type of diagnostic function, the user receives comprehensible error messages in text form, including information on possible causes as well as instructions for dealing with them.
Siemens has implemented new algorithms for this. “Intensive research in the laboratory and in systems in the field has enabled us to record and identify the various signal patterns,” says Niemann Gøbel, describing an important step. Future Coriolis flow meters from Siemens are to permit air/gas monitoring. This will allow the user to set a limit for the air or gas volume fraction, for instance, after which the measuring device goes into safety mode. As the device can also record the measurement deviation, the user retains flexibility when it comes to programming the diagnostic function according to his requirements.
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