America in the 21st century is well aware that it has a considerable investment in utility infrastructure, and knowledge of the condition of these critical assets has become crucial to planning maintenance and improvements. "The problem for wastewater utilities," Carson observes, "is that often the pipe network is 100 years old and so corroded that the whole pipe network needs replacement--and it's the largest asset class in terms of replacement value."
Carson details three approaches to caring for pipes, pumps, and motors as follows:
- " 'Run to fail,' i.e., wait until the pump or motor fails and--usually--race out and fix it or replace it;"
- "Preventive maintenance, i.e., periodic maintenance of a pump or motor to avoid waiting for it to fail;"
- "Predictive maintenance - the utility determines the state of each asset and can plan for servicing, or replacement, of a pump or motor."
Carson prefers the third way, "a much more proactive approach, generally known...as Condition Based Monitoring, which in practice is the same as Predictive Maintenance." To work, however, this latter approach requires data that many plants lack, and are unsure of how to collect. He suggests five key types: insulation resistance of motor windings, pump flow rates, pump volume per cost of energy, detailed pump fault data, and vibration analysis (noting that "to get vibration data, you need...sensors.").
Carson concedes "that adopting predictive maintenance strategies doesn't mean that every failure will be known in advance." Emergencies will always be with us. However, "the benefit you have with...predictive maintenance is that you can now have a lot more confidence of the state of you assets and you run maintenance program more proactively and most cost-effectively." Best of all, because you have accurate, data-based knowledge of your system, "you can plan the most effective capital works, replacement, or service program."