PUMPING SYSTEM
TROUBLE ANALYSIS GUIDE |
COMPLAINT |
POSSIBLE CAUSE |
RECOMMENDED
ACTION |
| No circulation |
Set screw not tight,
coupler
loose on shaft
Impeller slipping on shaft
Air-bound system
Air-bound pump
Broken pump coupler
Clogged impeller on piping
System valve closed
Pump electrical circuit broken |
Tighten set screw in
recess in the shaft
Check to see if impeller is placed on the
key way of the shaft
Tighten impeller nut
Vent system
Vent pump casing
Replace; check alignment
Locate and remove obstruction
Open
Check all related low and line
voltage circuits |
| Inadequate
circulation |
Air-bound system
Air-bound pump
Clogged impeller or piping
Clogged strainer
Pump impeller damaged
Insufficient NPSH
(Net Positive Suction Head)
Pump too small
Partially air-bound pump
Pump running backwards (three phase)
Improper motor speed |
Vent system
Vent pump casing
Locate and remove obstruction
Remove and clean screen
Replace
Lower pump or raise pressure or relocate
Replace pump or impeller
Vent pump casing
Reverse any two motor leads
Check wiring and voltage |
| Pump or system noise |
Entrained air
Pump cavitation
Pump misalignment
Worn pump coupler
Excessive water velocity
Poor foundation (base-mounted)
Pipe vibration |
Vent system
Lower pump or raise pressure or relocate
(See note)
Re-align pump
Replace; check alignment
Install balancing cocks or parallel piping
Provide rigid foundation with adequate
grouting
Provide adequate pipe support |
| Premature failure of
pump components |
Improper pump (size)
(type)
Improper pump location
Pump misalignment
Excessive water treatment
Over-oiling of pump
Under-oiling
Pump operating close to or beyond
end point of curve
Excessive piping load |
Replace
Relocate
Re-align
Check manufacturer’s instructions
Check manufacturer’s instructions
Check manufacturer’s instructions
Balance system
Provide proper pipe support |
| Seal failures within
1 year period or less in a closed system |
Excessive dirt, sand
and oxides
Excessive or improper water treatment
Pump Cavitation:
1. Improper selection
2. Compression tank location
Air-seal without lubricant (water)
Excessive temperatures
Pumps run without fluid |
Clean system
Check for proper water treatment
recommendations from pump manufacturer
Check pump operation on its curve-overloading
High head pump must have compression tank
on suction side of pump
Vent air from pump volute
Check type of seal and maximum operating
temperature from manufacturer
Pumps must be primed before operation |
Seal Pitting
- Oxygen corrosion
- Magnetic iron oxide |
Caused by wear and
excessive amounts
of free oxygen |
Check if system has a
constant lead
Fresh water feeding carries oxygen into
the system |
| NOTE: Cavitation can be recognized by low
rumbling or sharp rattling noises. The situation is created by the lack of available net
positive suction head (NPSH). The pressure at some point in the pump falls below the vapor
pressure of the water, causing flashing and the formation of bubbles, which are carried
into the volute where the higher pressure causes them to implode. This can eventually
destroy the pump. |