Page 217 - Shale Shakers Drilling Fluid Systems
P. 217
CENTRIFUGAL PUMPS 199
Centrifugal pump troubleshooting:
1. PUMP WILL NOT REACH DESIGN FLOW RATE 3. PUMP OPERATES BUT CONTINUALLY LOSES PRIME
A. Insufficient NPSH (noise may or may not be A. Insufficient NPSH
present) • Redesign suction piping; possibly enlarge diameter
• Redesign suction piping; possibly enlarge • Keep elbows, and so forth, at a minimum
diameter B. Check for entrained air or gas
• Keep elbows, and so forth, at a minimum C. If small whirlpools appear on top of liquid level,
B. System head requirements greater than anticipated install baffle plate
• Redesign system piping; possibly enlarge
diameter 4. EXCESSIVE NOISE—WET END
• Keep elbows, and so forth, at a minimum A. Cavitation—insufficient NPSH
• Increase impeller diameter • Redesign suction piping; possibly enlarge diameter
C. Plugged impeller, suction line, or pump casing by • Keep elbows, and so forth, to a minimum
fibrous or settled solids • Abnormal fluid rotation due to complex piping
• Clean and install strainer over suction line B. Impeller rubbing
• For fibrous material, possibly enlarge pump • Inspect and reset impeller
D. Entrained air from atmosphere • Inspect bearing assemblies for end play
• Check suction-line fittings and gaskets for leaks
5. EXCESSIVE NOISE—POWER END
• Repack pump stuffing box
A. Overloaded bearing with races flaking or pitting
• Check suction pit for vortex
• Suction pressure and/or fluid specific gravity
• Check for minimum suction-line submergence
may exceed bearing design
• Check degasser
E. RPM too slow B. Bearing contamination—raceways scoured, pitted,
or rusted
• Check motor speed
F. Wrong rotation direction • Work with clean tools and clean the area around
pump; provide cover from wash-down water
• Reverse any two of the three leads on a
• Clean pump housing before removing
three-phase motor
• Use clean solvents and flushing oil
C. Impeller worn, has improper clearance, etc.
• Protect bearings from moisture when not in use
• Inspect impeller and reset to proper clearance
(wrap in clean paper or clean cloth)
• If wnrn, replace
• Clean interior of pump housing before replacing
2. NO DISCHARGE OR FLOW bearings
A. Motor horsepower too small • Inspect oil lip seals
• Replace motor with larger size and proper rpm • Inspect plugs and tapped openings for tight
• Motor cannot rotate impeller closure
B. Not properly primed C. Worn bearings
• Repeat priming operations • Inspect and replace bearings
• Try to have a flooded suction • Improper lubrication including brown or bluish
C. Suction lift too high discoloration on races; stiff, cracked grease;
• Rearrange piping failure of ball retainer; dirty or improper amount
• Increase suction head of lubricant; improper lubricant grade(s)
• May need larger impeller • Check shaft straightness
• Check motor speed • Check bearing alignment
• May need larger pump for higher suction lift • Check housing bore for alignments
• Check suction line and pump for plugging D. Check for electric arcing from static electricity,
• Check direction of rotation; if incorrect, electrical leakage, or short circuiting.
change any two leads to motor Note: When mounting a bearing on a shaft, use a proper size
ring and apply pressure against the inner rings. When mounting
• Check for entrained air or gas
in a housing, press against the outer ring. Apply pressure slowly
• Move pump down to a lower level and evenly.
