- 21 -
12. Causes of Trouble and Troubleshooting
Problem
Cause
Countermeasure
● Wiring contact is bad.
● Thermal protector is activated
by overload.
● Earth leakage breaker is acti
-
vated by leak.
● Dry running without liquid on
suction side
● Air enters through suction side.
● Suction port is crushed.
● Pressure in inlet portion is
as low as or lower than vapor
pressure of the liquid.
● Liquid viscosity is too high.
● Valve is closed.
● Piping resistance is too high.
● Gear is worn out.
● Dry running without liquid on
suction side.
● Lock due to gear swelled
● Locking due to expanded gear
● Foreign matter sticks to gear
● Gear is damaged.
● Magnet capsule hits rear cas
-
ing.
● Valve is closed.
● Piping resistance is too high.
● Pump selection on
chemical(corrosion) resistance
is wrong.
○ Examine and repair defec
-
tive part.
○ Lower viscosity of liquid or
discharge pressure.
○ Examine and repair or replace.
○ Supply liquid or open suction
side valve.
○ Examine suction side piping
and repair.
○ Replace with a new, uncrush
-
able pipe.
○ Lower liquid temperature or
piping resistance.
○ Lower viscosity.
○ Open valve.
○ Adjust piping.
○ Replace with new gear.
○ Supply liquid or open suction
side valve.
○ Select a correct pump mate
-
rial.
○ Lower liquid temperature.
○ Disassemble and remove for
-
eign matter.
○ Replace with new gear case
unit.
○ Disassemble and repair or
replace parts.
○ Open valve.
○ Adjust piping.
○ Select a correct pump mate
-
rial.
Motor stops
while in opera-
tion.
Liquid cannot be
pumped up, or
capacity is insuf-
ficient.
Magnet coupling
disconnects.
Problem
Cause
Countermeasure
● Plug is out of socket.
● Contact is bad or there is a
break in wiring.
● Motor is malfunctioning, wire
in motor is broken.
● Earth leakage breaker is acti
-
vated by leak.
● Breaker is activated due to lack
in power capacity.
● Dry running without liquid on
suction side
● Foreign matter sticks to gear.
● Gear is damaged.
● Magnet capsule hits rear cas
-
ing.
● Gear is worn out.
● O ring is damaged.
● Bolt is loosened.
● Corrosion resistance is unsuit
-
able.
● Dry running without liquid on
suction side
● Air enters through suction side.
● Suction port is crushed.
● Inside of pump is dry.
● Pressure in inlet portion is
as low as or lower than vapor
pressure of the liquid.
● Gear is worn out.
● Suction height is too high.
○ Insert plug into socket.
○ Examine and repair defec
-
tive part.
○ Repair or replace.
○ Examine and repair or replace.
○ Increase capacity.
○ Supply liquid or open suction
side valve.
○ Disassemble and remove for
-
eign matter.
○ Replace with new gear case
unit.
○ Disassemble and repair or
replace parts.
○ Replace with new gear.
○ Replace with new O ring.
○ Fasten tightly again.
○ Select correct pump material.
○ Supply liquid or open suction
side valve.
○ Examine suction side piping
and repair.
○ Replace with new, uncrush
-
able pipe.
○ Supply liquid through dis
-
charge side or suction side.
○ Lower liquid temperature or
piping resistance.
○ Replace with new gear.
○ Lower the suction height.
Motor cannot be
started.
Too much noise or
vibration
Liquid leaks.
Self-priming can-
not be made
