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Vibration Monitoring Gives Impressive ROI at Tampa WWTP

Career Vibration Analysts Tom LaRocque, Gary Kaiser, and Joe Spencer co-authored "Continuous Vibration Monitoring of Wastewater Pump Stations" in the August 2008 online monthly trade journal Pumps & Systems "the voice of the pump and rotating equipment industry," with "more than 42,500 readers across the globe."

"The City of  Tampa's Howard F. Curren Wastewater Plant uses vibration analysis hardware and process controller equipment to protect critical machinery against damage from mechanical failures or environmental changes, ensure survivability, and prevent unscheduled downtime and costs.  This system uses relays to trigger alarms, or shutdowns, and is integrated to the main plant's Supervisory Control and Data Acquisition (SCADA) system.

The plant is "a state-of-the-art facility that treats all wastewater discharged from approximately 100,000 accounts in the City of Tampa system.  The plant has a permitted capacity of 96 [million gallons a day], with an average daily flow of 60mgd."  The stakes are high; "Pump failures can often be damaging to the pumps and auxiliary equipment.  Moreover, the cost of a new pump motor can be as high as $450,000, and the cost to repair an existing unit can approach $175,000 after a catasrophic failure."

However, "A protection system that monitors the vibration levels and can be integrated to a shutdown circuit minimizes flow interruptions and the amount of damage to that equipment...The Wastewater Department installed on unit as a trial on a large (700 hp) pump and motor combination at a major pump station.  Vibrations were detected and repairs were made for less than $500 that saved damage to the expensive pump and motor.  Plans are in place to install monitors at all major pump stations over the next two years."

"Periodic monitoring might be sufficient to identify general, long-term machinery conditions, but to capture transient conditions that can cause catastrophic failures the team determined that continual monitoring was required.  Given the unmanned pump stations, an integrated system that could alert a technician at the plant of an issue with the pump station equipment."

The report gives serious consideration to how each of the hardware components and locations in Tampa's wastewater monitoring system were carefully selected.

"Comparing the cost of repairing a pump station with with an 800-hp motor ($175,000) with the price of a typical monitoring system (a two-channel system is approximately $2,500, or approximately $1,500 per measuring point) justified the project.  The initial approval to outfit one major lift station was decided in 2006, and a unit has been in service since then.  Another pump motor failure costing an estimated $160,000 further justified the project and renewed interest in a relatively low-cost 24-hour protective device."

The study concludes with a list of "factors...critical in convincing management of the benefits of vibration monitoring to the predictive maintenance program and the need to expland the program to other pump stations."  Leading the list is this: "Cost of the [monitoring] equipment is much less than the cost of repair or replacement of pump and motor."

Click for a Virtual tour of the Howard F. Curran Advanced Wastewater Treatment Plant.

1 comment :

  1. It's hard to believe that "the cost of a new pump motor can be as high as $450,000," but that certainly makes the case for protecting it with a $1,500 to $2,500 monitor. And pump motors for some large dredges do cost almost half a million dollars.

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