Pump Maintenance & Operations

Dave Krebs – Wilfley

David Hyde – Thurston Machine Inc.

Outline (information is dangerous)

Pump systems Pump selection & sizing Pump performance vs. System curves Pump selection issues Installation issues Startup / Operation Maintenance Issues Trouble shooting (performance changes)

Pump Systems Clear liquid Slurries – settling vs. non-settling Minimum stable pumping velocities Pipeline system stability

Pump selection & sizing Flow (gpm or M3/hr) – determines size Head (TDH) – determines speed/impeller size Specific gravity (concentration/% solids) –

affects HP demand Maximum particle size – sets impeller design NPSH – available vs. required Material of construction – alloys, hard irons,

non-metallics or elastomers Motor selection – HP considerations

Formulas PSI = (feet x SG)/2.31 Feet of slurry = (PSI x 2.31)/SG Specific Gravity = 1

% solids by wt+ % liquid by wtSG of solids SG of liquid

TPH = (GPM x % solids x SG)/3.998 GPM = TPH x 3.998/% solids x SG Velocity = .4085x GPM/pipe ID x pipe ID (inches) Water SG = 1.0 Aggregate SG = 2.65 $ electrical costs = .746 x cost/kw x operating hours x HP

Pump performance vs Pipeline System curve – “the key”

Centrifugal pumps always operate at the intersection of the pipe line’s system curve and the pump curve.

When? ALWAYS Place conservatism in motor HP (not

head or flow figures), do not use safety factors.

Installation considerations

Allow access for maintenance on pump Pumps do not support piping, use

flexible connections Supply adequate foundations for pump

& motor assemblies Sump design is important – consider 2

minute retention minimum

Startup & operation

Check for proper rotation Check and remove debris from sump

and pipes Check valves (open) After startup check sump level (stable)

Maintenance

Adjustment of pump internals Replacement of hydraulic components Lubrication Record keeping

Trouble shooting (determine root cause) If conditions change, adjustments in pump speed

and/or impeller diameters may require changes. Flow rate increases – check if system head

decreased, is motor tripping on overload? Flow rate decreased – check if system head is

increased, obstruction in pipe, worn impeller, check pump speed is as specified.

Vibrations – check obstruction in suction, cavitation, impeller with solid particle logged in vane.

Dynamic seal leakage – while running or at shut down? – check suction conditions, wear in parts, pump speed, changes in system?

The End – questions?