Xylem Vogel Pumpen LR Serie Instructions De Montage, De Service Et De Maintenance page 55

Installation, Operating and Maintenance Instruction
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■ ■ ■ Forces in pipeline too high (pump unit under strain)
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Cause
Back-pressure too high
Back-pressure too low, discharge too low
Speed too high
Speed too low
Flow too little
Flow too big
Impeller diameter too big
Impeller diameter too small
Pump and/or pipes not completely filled with liquid
Pump or suction/intake pipe blocked
Air pocket in pipeline
Suction height too big / NPSH of system too small
Air being sucked in
Air being sucked in through shaft sealing
Direction of rotation is wrong
Inner components suffering from wear
Density and/or viscosity of liquid handled is too high
■ Lines and roughness at shaft
■ Deposits on mechanical seal
■ Impeller out of balance
Electricity supply not right (2-phase running)
Sealing insufficient
Bearing damaged
Relief fittings insufficient
System-related vibrations (resonance)
Model LR, LMR, LRZ, LMZ
Solution
check facility for pollution, open discharge valve
reduce resistance in discharge pipe (e.g. clean filter if
necessary)
use larger impeller (note available motor power)
throttle discharge valve
reduce speed
compare speed of motor with specified pump speed (rating
plate)
when adjusting speed (frequency transformer) check reference
value setting
increase speed (check available motor power)
compare speed of motor with specified pump speed (rating
plate)
when adjusting speed (frequency transformer) check reference
value settings
increase min. flow (open discharge valve, bypass)
reduce flow (throttle discharge valve)
use smaller impeller
use larger impeller (check available motor power)
fill
vent
clean
vent
improve course of pipe
increase liquid level and admission pressure
reduce resistance in the intake/suction pipe (change course
and rated width, open shut-off valves, clean filters)
increase liquid level
check if suction pipe is vacuum-tight
clean sealing pipe
increase sealing pressure
replace shaft sealing
swap over two phases of power supply (to be done by an
electrician)
replace worn parts
seek assistance
replace parts
clean
replace mechanical seal if necessary
if necessary provide additional rinsing or quench
remove blocks/deposits
replace impeller if broken or unevenly worn
check shafts to ensure that they are running true
change (support pipes, use compensators, etc.)
is foundation plate/frame properly cast in place?
check voltage of all phases
check cable connections and fuses
tighten screws
replace sealing
replace
clean relief openings in impeller
replace worn parts (impeller, split rings)
adjust in line with the system pressure/intake pressure given on
ordering
seek assistance
page 51