68
180R9270 / IOM APP S 674 - v01 / 03.2013
Instruction
Trouble shooting guide for APP and APP S 674 pumps
8
03.2013
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 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 connections mounted 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 a more flexible hose. Danfoss 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 and the rest of
the system/plant.