CLIMATIC & VIBRATION TESTING: PATROL MONITORING D
ecades ago, an older colleague told me a noisy pump was caused by a defective bearing and when asked how he knew, he produced a large screwdriver, placed the
blunt end to his ear and the other end against the pump casing. “Listen to that,” he said. “Definitely the bearing.” For me it was like holding a conch shell to my ear and expecting to hear a passing trawler; he clearly had the ear for it and I didn’t. Years of dealing with plant maintenance
had tuned his ears to the point where he could make a good assessment of the defect and confidently instigate the repair. Now, there are more repeatable and
reliable options for assessing machinery vibration and analysing defects using accelerometers connected to instruments, which gather the data to be analysed by software that is able to identify defects and highlight trends.
HANDHELD VIBRATION SAMPLING One such instrument is Schaeffler’s FAG Detector III handheld vibration monitoring device. With its free of charge Trendline software, the device enables the user to collect, store and analyse vibration measurement data, based on a database of over 20,000 different bearing products from a range of suppliers. The FAG Detector III is frequently used
in patrol monitoring, a routine in which maintenance engineers can sample vibration data from equipment in a number of installations sited along a patrol route around the facility. Vibration data is measured and recorded
at each sampling point and the data analysed against three parameters, including velocity, acceleration and enveloped acceleration. Velocity is used to indicate any
mechanical issues such as imbalance, misalignment or looseness. Acceleration typically monitors gear defects and progressing bearing defects while enveloped acceleration (or demodulation) is a measure of high-frequency impact type events, typified by early bearing or gear faults.
IDENTIFYING TRENDS Explaining the Trendline software that comes with the instrument in more detail, Schaeffler service engineer Ian Pledger told me that it identifies trends in the data and can characterise the cause of the failure and the kind of maintenance that’s likely to be required. The software enables the user to analyse
the vibration trends over time and to suggest when and where a failure on a motor, pump or fan is likely to occur. This
38 /// Environmental Engineering /// March 2018 Vibration
Jonathan Newell looks at patrol sampling machinery with vibration measuring equipment to avoid costly downtime
allows maintenance to be planned and carried out at a time convenient to the user rather than having to contend with unplanned downtime in the middle of a production run. “In the hands of an experienced user, the
FAG Detector III is a very powerful predictive maintenance aid. But it can also be used by an inexperienced engineer to patrol monitor and identify increasing trends,” he explains. Such trend analysis is an important part
of keeping equipment well utilised and preventing costly, unplanned outages and maintenance. Pledger went on to explain that Patrol monitoring is ideal for many companies that have a high number of assets or machines that are critical to their production process but which may have limited maintenance budgets. Vibration
monitoring is relevant to all industry sectors, in fact anywhere where rotating equipment and machines are present. Any plant that utilises electric motors, gearboxes, air compressors, fans, conveyors or pumps can benefit from vibration monitoring of this kind. When asked for examples of the
industries in which patrol monitoring is performed, Pledger tells me: “Schaeffler has customers in the process industries, such as food and beverage, chemicals, metal processing, quarrying and cement,
but also in discrete manufacturing such as automotive and aerospace, as well
as the rail industry. In
recent years, Schaeffler has provided vibration monitoring services to the pharmaceuticals industry, which monitor the condition of very large air handling systems that must remain operational at all times in order to keep drugs production at a certain positive atmospheric pressure. Schaeffler has also provided vibration monitoring services to the Health sector where HVAC systems in blood storage facilities need to be monitored continuously.”
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