43
180R9263 / IOM APP 5.1-10.2 Appendices - v02 / 01.2013
Instruction
Trouble shooting guide for APP pumps
8
5.
Noise from installation
Cause
Remedy
Comments
5.1 Inlet/outlet connections (hoses/pipes)
5.1.1 Use flexible hoses at inlet/outlet connec-
tions. Danfoss A/S can provide flexible
hoses. Please contact Danfoss sales office
for further information.
5.1.2 Mount the connections to the frame by a
vibration damper mounting plate.
Non-flexible connectionsmounted directly on
the frame will cause even small pressure
pulsations from pump and create vibrations in
the system/plant.
5.2 Length/dimension of inlet/outlet line
5.2.1 Increase pipe diameter and/or reduce the
number of bends.
Too small pipes or too many bends may create
too fast flow/turbulence through the pipes and
thus increase the noise level.
5.3 Hose stiffness
5.3.1 Use amore flexible hose. Danfoss A/S can
provide flexible hoses. Please contact
Danfoss sales office for further informa-
tion.
Too stiff hoses cannot damp the small pressure
pulsations from the pump, and subsequently
vibrations occur in the system/plant.
5.4 Hoses/pipes mounted directly on frame
5.4.1 Mount the connections to the frame by a
vibration damper mounting plate.
If the hoses are mounted directly on the frame,
the small pressure pulsations from the pump
can be transferred to the frame and the rest of
the system/plant.
5.5 Vibration damper under the electric motor
5.5.1 Mount a vibration damper below the
motor/pump.
When no damper is installed below the electric
motor, vibrations from the motor and pump
may be transferred to the frame/r est of the
system/plant.
Instruction
Trouble shooting guide for APP pumps
9
6.
Typical signs of wear
6.1 Valve plate
Picture 1
A normally worn valve plate has no marks/scratches but only a slightly
polished surface.
No scratches or marks should be felt. The surface must be flat and level.
Picture 2
Scratches
A worn valve plate has scratches, and/or a polished surface. Even small
scratches will give a loss of flow.
Picture 3
A good way to identify a worn valve plate is to hold a straight knife edge
over the valve plate. When holding it up to the light, it will be possible to
see any space between the knife edge and the valve plate. See picture 3.
If any light can be seen between the two arrows on the picture, the valve
plate is worn.
If any scratches or marks can be felt by running a fingernail over the surface,
the valve plate is worn.
The valve plate on picture 3 is highly damaged.
