TROUBLESHOOTING
DESMI Pumping Technology A/S
Tagholm 1
9400 Nørresundby
– Denmark
Tlf. nr.: +45 96 32 81 11
Fax +45 98 17 54 99
61
E-mail: [email protected] www.desmi.com
FAULT
CAUSE
REMEDY
and cables
The pump makes
noise
1. Cavitation in pump
Suction lift is too high / Suction
line wrongly dimensioned / Liquid
temperature is too high
7.1. Mechanical seal failure analysis
Description of
poosible failure
Impacts on the
pump/system
Indications of
failure
How to avoid
Pump settled (due to
seizing sliding rings
in mechanical shaft
seal) due to standstill
after storage
Mechanical seal
failure/leaking after
short time
1. Initial leaking
after first start up
that does not
stop after short
time
1. Ensure correct
storage of pumps
2. Preventive
maintenance to
be followed for
long term
storage
3. Rotate pump
carefully by hand
prior to first start
up, to ensure
integrity of mech.
shaft seal
Pump settled (due to
seizing sliding rings
in mechanical shaft
seal) due to standstill
in system / stored
with water inside for
longer duration of
time
Medium could
change properties
when standstill in
pump based on the
environment and
type of medium
1. Higher power
consumption
than calculated
short time after
startup
2. Leakage from
mech. shaft seal
after start up
1. Rotate the pump
regularly, to
avoid seizing
2. If not possible,
pumps should be
drained
Lack of NPSH
available vs. NPSH
required
Cavitation duty,
creating vibration
and mechanical
damage
1. Vibration and
noise from the
pump
2. Wear on
impeller/seal
ring, and
possible leaking
mec. seal
1. Make sure to
have sufficient
NPSHa at all
times
Summary of Contents for NSL 100-215
Page 2: ......
