Davey VM Series Stainless Steel Vertical Multistage Pumps - Manual (Page 5)

5
Trouble Shooting
Switch the pump OFF before doing any work on it
SYMPTOM CAUSE REMEDIES
PUMP TURNS BUT NO a) The internal parts are a) Dismantle the pump and clean it.
DISCHARGE FLOW obstructed by foreign bodies
b) Suction pipe obstructed b) Clean all the pipes. If suction valve fitted, ensure it is fully open.
c) Air leaks in via suction pipe c) Check the tightness of the suction pipe line, up to the pump, and
make it airtight.
d) The pump has lost its prime d) Fill the pump to re-prime. Check that the foot valve seals and
does not leak.
e) The suction lift is too high, e) Suction height too great (check the NPSH of the pump installed).
this is generally accompanied Install the pump closer to the water.
by cavitation noise
f) The pump turns the wrong way f) Check direction of rotation in main section.
g) The supply voltage to the g) Check the voltage on the terminals of the motor and the cross-
motor is too low sections of the conductors.
h) No incoming water flow h) Check water tank or mains for water.
(flooded suction)
THE PUMP VIBRATES a) Loose on its foundation a) Check the nuts of the stud bolts and tighten them fully.
b) Foreign bodies obstructing b) Dismantle the pump and clean it.
the pump
c) Pump is hard to turn c) Check that the pump turns freely without abnormal sticking.
d) Incorrect electrical connection d) Check the connections to the pump.
THE MOTOR OVERHEATS a) Voltage too low: a) Check the voltage on the terminals of the motor; it should be
within ±10% of the rated voltage.
b) Foreign bodies obstructing b) Dismantle the pump and clean it.
the pump
c) Ambient temperature above c) The motor is designed to operate at an ambient temperature of
+40°C not more than +40°C.
THE PUMP DELIVERS a) The motor fails to run at its a) Dismantle the pump and correct the problem.
INSUFFICIENT PRESSURE normal speed (foreign bodies,
defective power supply, etc.)
b) The motor is faulty b) Replace it.
c) Pump poorly filled c) Fill the pump and bleed until there are no more air bubbles.
d) The motor turns the wrong d) Alternate two wires on the motor terminal block or the
way (three phase only) circuit-breaker to reverse the direction of rotation.
e) Suction leak e) Check and reseal fittings.
THE MOTOR TRIPS OUT a) The setting of the thermal a) Check the current with an ammeter, or set to the current rating
relay is too low (three-phase marked on the motor data plate.
motor)
b) The voltage is too low b) Check that the conductor cross-sections of the power cable are
adequate.
c) One phase is open-circuit c) Check it and correct where required.
d) The thermal relay of the circuit- d) Replace it.
breaker is faulty
e) Ambient temperature above e) The motor is designed to operate at an ambient temperature of
+40°C not more than +40°C.
THE FLOW IS IRREGULAR a) The suction height is a) Reread the installation conditions and recommendations in
exceeded these instructions.
b) The diameter of the suction b) The suction pipe must be sized to suit the application and be
pipe is smaller than that of at least the same diameter as the pump suction port.
the pump
c) The strainer and suction pipe c) Remove and clean.
are partially obstructed