Danfoss APP 1.0 Installation, Operation And Maintenance Manual page 59

Instruction
4. Noise from pump
Cause
4.1 Air in fluid
4.2 Bleeding conditions of pump
4.3 Min/max nominal inlet pressure
4.4 Pump reversing
4.5 High rotation speed (RPM)
4.6 Outlet pressure
4.7 Soft start/stop
Trouble shooting guide for APP pumps
Remedy
4.1.1 Ensure that the entire inlet line is bled
before starting up the system.
4.1.2 Ensure that air cannot enter into the inlet
line.
4.2.1 Follow the instructions "Initial start-up"
supplied with the new pump.
4.2.2 Ensure that the pump is completely bled
before start-up.
4.3.1 Ensure that inlet pressure is between 1
and 5 bar.
4.3.2 Check the pump for internal damage.
4.4.1 Dismantle pump and check if anything is
broken or worn (See "1. No flow", item 1.2
Pump reversing").
WARNING:
The pump must not run without water
for more than a few seconds. If the pump
takes in water from the high- pressure
outlet line, it builds up pressure and will
eventually be damaged.
4.5.1 If electric motor RPM is too high, dismantle
pump and check for damage.
4.5.2 If the RPM is within the specified range of
the pump data sheet and abnormal noise
remains, dismantle pump and check for
damage.
4.6.1 If outlet pressure is too low, check set
point of outlet pressure valve.
4.6.2 If outlet pressure is lower than mentioned
in the pump data sheet, please contact
Danfoss A/S RO Solutions Technical
Support.
4.6.3 If outlet pressure has exceeded its
maximum, check set point of outlet
pressure valve.
4.6.4 Check internal parts for wear/damage.
4.7.1 Check if noise is normal when the pump is
running at operation speed.
4.7.2 If noise is abnormal at operation speed,
check internal parts (see above).
180R9262 / IOM APP 0.6-1.0 Appendices - v02 / 12.2012
Comments
Small air bubbles will accumulate and create
large bubbles causing internal cavitation and
thus making the pump very noisy.
WARNING:
The pump can only run fewminutes with air in
the fluidwithout being damaged.
The pump and the inlet line must be com-
pletely bled before start-up, otherwise the
pump will cavitate and make high noise.
WARNING:
The pump can only run few minutes with air in
the fluid without being damaged.
Too high inlet pressure causes too high
pressure inside the pump damaging the pistons
and eventually the pump.
Inlet pressure below 1 bar causes cavitation and
insufficient internal lubrication resulting in wear
on internal pump parts.
Mount a low-pressure switch before the pump
and check its set point/ function. The low-pres-
sure switch will ensure that the pump does not
start until the inlet pressure has reached 1 bar.
If pump rotates in wrong direction, it will take in
water fromthe high-pressure outlet line.
Pressure will be built up inside the pump and it
will eventually be damaged.
Higher RPM than specified in the pump data
sheet results in wear of the pistons, i.e. pistons
may be damaged.
High RPM will also increase pressure pulsations
from the pump, and the noise level will
increase.
If RPM is changed, noise frequency will also
change.
At too low outlet pressure, the pump will create
higher pressure pulsations and thus make
noise. Too low pressure also causes insufficient
internal lubrication and wear on internal parts.
Pump may eventually be damaged.
Too high outlet pressure may damage the
pump.
Noise frequency changes during soft start-up/
stop.
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