Equipment Maintenance and Support Systems
Pumps and drives
Centrifugal pumps dominate plant service. Affinity laws: flow scales with speed, head with speed squared, and power with speed cubed. Cavitation - rattling, dropping flow, pitted impeller - means available NPSH is too low; correct by raising suction head, clearing a clogged suction, or lowering liquid temperature. Positive displacement pumps move a fixed volume per stroke or revolution and require a discharge relief valve.
Maintenance strategy
Reactive, preventive, predictive. Preventive work is calendar- or run-hour-based: lubrication, packing or mechanical seal inspection, belt tension, impeller clearance. Predictive work is condition-based: vibration analysis, oil analysis, thermography, motor current signature. A computerized maintenance management system tracks work orders, spares, and failure history. Root-cause analysis asks why a failure occurred; replacing the same bearing repeatedly without asking is not maintenance.
Support systems
Standby generators must be exercised and load-tested. Blowers need clean filters and correct oil levels. Instrument drift is a common cause of apparent process failure - verify the meter before changing chemical feed rates. Keep spares for critical single-point failures and know the lockout/tagout points for each unit.
Traps
Confusing water horsepower with brake horsepower; assuming power rises in proportion to speed (it rises with the cube); adjusting the discharge valve while ignoring a suction-side problem.
Worked example
A pump moves 500 gpm against 40 ft of total dynamic head. Water horsepower = (500 × 40)/3,960 = 5.05 hp. If the motor draws 7.5 brake horsepower, wire-to-water efficiency = 5.05/7.5 = 67%. A vibration trend rising over several weeks calls for inspection, not a larger motor.