Heed the warning
August 1st 2010

Maintenance engineers have long known the benefits of monitoring vibration; however the virtues of what can be achieved are not always appreciated by others, according to Chris Hansford, MD at Hansford Sensors.Warnings may be disregarded – sometimes with catastrophic results.

Hansford says: "Such a situation was reported to us via one of our overseas customers recently. A maintenance engineer team leader contacted our customer for advice on a potential equipment failure they had identified. The team had discovered that a conveyor pulley bearing had developed high levels of wear over a short period of time. The production department decided that, instead of an unplanned shutdown (recommended by the maintenance team), they would ignore the warning and continued to run the pulley until the planned shutdown date – three weeks after the initial bearing fault detection.

"The maintenance team purchased a stock item sensor; HS-423 (Dual output -4-20mA acceleration into the PLC and AC output via a data collector).Within 24h these were installed on the conveyor pulley bearing, giving management instant warning if the problem progressed.

The identified 'g' (acceleration) levels shown by the HS-423 sensor doubled and was sent into alarm as detected levels surpassed warning parameters. These reading were backed-up by acceleration readings taken via a hand-held data collector.

The levels increased substantially in the hours before the failure.

Operators chose to ignore the warnings. The bearing failed catastrophically, catching fire, damaging equipment and putting lives at risk. The result was expensive repairs, 24h shut down of the conveyor, and lots of paperwork.

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