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Troubles
Symptom on pump
Cause
Countermeasures
When disch. valve
closed
When disch. valve
opened
D i s c h a r g e
capacity is
small.
Pressure gauge &
vacuum gauge indi-
cates normal figure.
Pressure is high but
vacuum is normal.
•
Too high actual
head or too large
pipe resistance
•
Check actual head of
discharge piping and
loss of pipe resistance.
Pressure is low and
vacuum is very low.
Pressure is low and
vacuum is low.
•
Motor rotates in
reverse
•
Interchange motor
wiring.
•
Lowered power
voltage
•
Check voltage or fre-
quency.
•
Overload
•
Check density and vis-
cosity of liquid
•
Too high ambient
temperature
•
Ventilate
D i s c h a r g e
capacity is
rapidly re-
duced.
Vacuum gauge indi-
cates high figure.
•
Foreign matters
clog suction piping.
•
Remove foreign matters.
•
Foundation is not
perfect.
•
Re-install the pump.
•
Loosened mount-
ing bolts.
•
Re-tighten
•
Cavitation occurs.
•
Resolve the reason of
cavitation.
•
Worn or melted
bearing
•
Replace
•
Worn bearing of
motor
•
Replace bearing or
motor
Motor is ov-
erheated.
Pump vib-
rates.
•
Broken magnet
capsule or spindle
•
Replace
•
Bad dynamic bal-
ance of drive mag-
net
•
Resolve the reason or
replace
