EBARA GP Operating And Maintenance Manual page 33

performance
Malfunctioning
check valve
Incorrect stop
frequency
Prolonged
inactivity resulting
in scaling,
oxidation and
limescale
STUCK PUMP
formation
Presence of
foreign objects
Blocked or
broken bearings
Worn bearings
Worn or broken
impellers
NOISY PUMP Presence of air
AND/OR
EXCESSIVE
Undersized or
VIBRATION
incorrectly
secured pipes
Wrong duty point
setting
Pump undersized
for system
requirements
Pump not
properly primed
and doesn't
achieve required
performance
Blocked or
PUMP OPERATES
obstructed foot
BUT DOESN'T
valve
DELIVER
ENOUGH
Wrong rotation
PERFORMANCE
sense (low
(FLOW RATE
performances)
AND/OR
Improperly sized
PRESSURE)
pipes (excessive
pressure losses)
Excessive height
difference (if
overhead
installation)
Excessive liquid
viscosity (if
different than
water)
Excessive wear
or mechanical
seal failure
Excessive wear
WATER
or breakage of
LEAKAGE
gaskets
Pipes not
properly tightened
at joints
PUMP RUNS IN
Unit foot valves or
REVERSE WHEN
non-return valves
STOPPED AND
not functioning
STARTS AGAIN
properly
IMMEDIATELY
Check or change the
check valve
Check and set
proper value
Careful pump
cleaning and
maintenance
Remove the foraign
objects
Change bearings
Change bearings
Change impellers
Check proper pump
priming
Correct sizing of
suction and
discharge pipes and
secure pipes
Set the proper duty
point
Check pump
performance if it
complies with
system
requirements
Properly prime the
pump and check for
air infiltration and/or
leaks
Remove obstruction or
unblock foot valve. If
necessary, replace
foot valve
Check the rotation
sense and phases
connection
Sizing the system
piping properly
Decrease suction
height
Pump model not
suitable for service
or incorrect pressure
drop calculation /
pump selection
Change mechanical
seal
Change gaskets
Check correct
tightening of joints
Check correct
functioning of non-
return valves and
replace if necessary
ENGLISH
Incorrect setting
of set pressure
and restart
pressure
parameters
Incorrect setting
and adjustment of
the pressure
switches
TOO No or incorrect
FREQUENT preloading/sizing
PUMP of pressure
RESTARTS vessel
Faulty or
defective
pressure vessel
membrane
Incorrect setting
of set pressure
and restart
pressure
parameters
Faulty or
PUMP
malfunctioning air
DISPRIMED*
supply unit
LACK OF
Air supply suction
WATER-AIR
valve blocked
EXCHANGE*
* Valid only for GP installation with air feeders on systems with
diaphragmless tanks and/or liquid assemblies
11.4. CALIBRATING THE PRESSURE SWITCHES
The pressure switches are only present in sets with an EP, SP-
EFC or SP-MFC control panel.
The pressure switches are calibrated (at ambient temperature)
according to the following standard table:
Pressure switch calibration table:
Type of
Pump
operation
sequence
Pump no. 1
Stop
(or pilot pump)
Start
Pressure switch
no. 1
Pump no. 2
Stop
Pressure switch
Start
no. 2
Pump no. 3
Stop
Pressure switch
Start
no. 3
Pump no. 4
Stop
Pressure switch
Start
no. 4
With:
P0 = max pressure in bar of pump no. 1 (or pilot pump) with
the opening closed
P1 - P8 = calibrating pressures in bar (see the following table)
ΔP = minimum differential in bar (see the following table)
NB: depending on the characteristics of certain types of pumps
(with flat curve), the pressure switch for pump no.1 (or pilot)
may be calibrated at a stopping pressure P1= P0 – 0.3 bar Any
diaphragm tanks must be calibrated by the user at a pressure
Check and set
proper parameters
(see the control
panel user manual)
Correct adjustment
of pressure switches
Install adequately
sized pressure
vessel (if absent)
and/or check for
proper precharge
Replace membrane
or vessel
Check and set
proper parameters
(see the control
panel user manual)
Replace air supply
unit
Clean valve of
possible limescale
or replace air supply
unit
Calibrating
pressures
[bar]
P1=P0-10%
Sets with
P2=P1-Pmin
1 pump
P3=P1-0.5
Sets with
2 pumps
P4=P3-Pmin
P5=P3-0.5
Sets with
3 pumps
P6=P5-Pmin
P7=P5-0.5
Sets with
4 pumps
P8=P7-Pmin
Sets
9