45
180R9265 / IOM APP 16-22 Appendices - v02 / 01.2013
Instruction
Trouble shooting guide for APP pumps
Cause
Remedy
Comments
2.1 Wear on pump
Large internal leakage due to:
- Pre-treatment
- Main
fi
ltration
- Fluid type
- High
fl
uid temperature
2.1.1 Dismantle the pump.
2.1.2 Check valve plate.
Valve plate has marks/scratches on the
surface facing the port plate. Minor wear
on valve plate can cause large internal
leakage. See Index 6.1
2.1.3 Check port plate.
Port plate has marks/scratches on the
surface facing the valve plate. Minor wear
on port plate can cause large internal
leakage. See Index 6.2
2.1.4 Check cylinder barrel.
Liners in cylinder barrel may be scratched
or worn. Insert a piston in the liner and
check the
fi
t. If there is any space
(clearance) between liner and piston, liner
or piston is worn.
2.1.5 Analyse
fl
uid for content of particles.
2.1.6 Check that
fi
lters are OK and working
correctly.
2.1.7 Install correct pre-
fi
lter (1
μ
m nom.
string-wound
fi
lter).
2.1.8 Check that the correct
fi
lter type is used
(particles in
fl
uidmust not exceed 10
μ
m).
Danfoss RO Solutions supply
fi
lters.
Please contact Danfoss sales o
ffi
ce.
2.1.9 The APP pump is designed for seawater
operation; for any other
fl
uid, please
contact Danfoss sales o
ffi
ce for further
help.
2.1.10 If
fl
uid temperature is above 50°C, stop
the pump immediately.
2.1.11 Check internal parts (see above).
See instruction on replacement criteria
(521B0925).
Are available on www.ro-solutions.com
Typical signs of wear:
Polished surface all over the swash plate.
Normally, only half of the swash plate = the
pressure side is polished. See index 6.3.
If the ring is missing, the piston is very worn.
The
fi
lters can be bypassed, even if they are
correctly mounted. Some
fi
lters can create
channelling where particles can pass trough the
fi
lter in tunnels. String wound
fi
lters are
typically channelling
fi
lters. A string wound
fi
lter may have a
fi
ltration e
ffi
ciency of only
50%, which will cause internal wear and
must
always be followed by a main
fi
lter
.
Insu
ffi
cient
fi
ltration means that too many or
too large hard particles can pass the main
fi
lter
because it is damaged, bypassed or simply too
poor. Filtration e
ffi
ciency must be 99.98%
(Beta = 5000) at 10
μ
mto prevent abnormal
wear of the pump.
Temperature > 50° C will cause wear on internal
pump parts. Mount a temperature switch and
check its set point / function. The temperature
switch will ensure that the pump stops at
fl
uid
temperatures > 50° C.
2.2 Low inlet pressure
2.2.1 Check that booster pump supplies the
right pressure/
fl
ow.
2.2.2 Check if
fi
lters require replacement.
If the pressure drop across the
fi
lters is too high,
the booster pump does not deliver su
ffi
cient
fl
ow/pressure. No pressure or low pressure
results in cavitation and insu
ffi
cient internal
lubrication causing wear on internal pump
parts.
Mount a low-pressure switch before the pump
and check its set point/ function. The low-
pressure switch ensures that the pump does
not start until the inlet pressure has reached
1 bar.
2.3 Rotation speed (RPM)
2.3.1 If VFD-operated, check frequency.
2.3.2 Check that rotation speed of the electric
motor is as stated on name plate on
electric motor. Check that the motor rotor
winding is not damaged.
Speeds below 700 rpm result in insu
ffi
cient
internal lubrication causing wear on the
internal pump parts.
2.
Reduced
fl
ow/reduced pressure