7.3. Starting and checking operations
Close the air vent holes (1), (2) (fig.3), for MXV-B,
MXV(L) 25-32-40 e MXV(L)4 25-32-40 Tighten the needle
screw (14.17) in the drainage plug (14.12) (fig. 3b) and clo-
se the air vent hole (14.04).
Start the pump with the delivery gate valve closed and
with the suction gate valve fully open. Immediately after-
wards, gradually open the delivery gate valve, adjusting
the point of operation within the limits indicated on the
name plate.
Check that the direction of rotation is as shown by the
arrow: i.e. counter-clockwise when viewing the motor
from the fan end for MXV-B 50, MXV(L)50-65-80,
MXV(L)4 50-65-80, i.e. clockwise when viewing the
motor from the fan end for MXV-B 25-32-40, MXV(L)
25-32-40 e MXV(L)4 25-32-40; Otherwise disconnect
electrical power and reverse the connections of two phas-
es.
Check that the pump works within its field of performance
and that the absorbed current shown on the name-
plate is not exceeded. Otherwise adjust the delivery
gate valve or the setting of any pressure switches.
If a priming loss occurs (interruption of delivery flow, de-
spite opened gate valves) or if a pressure oscillation is in-
dicated on the pressure gauge, repeat the venting opera-
tion on the suction side (2), make sure all the suction pipe
couplings are perfectly sealed and tighten the air vent
plug (2) and the draining plugs (3) on the suction side
(fig.3).
ATTENTION: when the pump is located above the
water level (suction lift operation,fig. 2A), after a
long idle period, before restarting the unit, check
that the pump is still filled with liquid and vented.
Otherwise, check for proper operation (opening and clos-
ing) of the foot valve and fill the pump with liquid (see
section 7.2.).
Never run the pump for more than five minutes
with a closed gate valve.
Prolonged operation without a change of water in
the pump causes dangerous increases of temperature
and pressure.
In systems in which it may be possible to operate with a
closed delivery gate valve, install a bypass valve (fig. 2)
to ensure a minimum flow of about:
0,3 m
/h for MXV(B) 25, MXV(L) 25, MXV(L)4 25,
3
0,4 m
3
/h for MXV(B) 32, MXV(L) 32, MXV(L)4 32,
0,5 m
3
/h for MXV(B) 40, MXV(L) 40, MXV(L)4 40,
1,0 m
3
/h for MXV-B 50, MXV(L) 50, MXV(L)4 50
1,5 m
3
/h for MXV(L) 65, MXV(L)4 65
2,6 m
3
/h for MXV(L) 80, MXV(L)4 80
When the water is overheated due to prolonged operation
with a closed port, stop the pump before opening the gate
valve.
To avoid any risk of danger to users and the creation of
harmful thermal stress in the pump and system due to
large temperature differentials, wait until the water has
cooled inside the pump before starting again or before
opening the drainage and filling plugs.
Care must be taken when the pumped fluid
has a high temperature. Do not touch the fluid
when its temperature is higher than 60 ˚C. Do
not touch the pump or motor when their sur-
face temperature is higher than 80 ˚C.
8. Maintenance and monitoring pump operation
Under normal operating conditions the pump-motor unit
will not require maintenance.
Conduct routine inspection on the pump and connected
parts to check for a perfect seal.
Check the seal on the shaft from the outside through
the coupling guard.
The special funnel-shaped upper cover is designed to
contain any small initial leaks.
Keep the pump and surrounding part clean so as to be
able to immediately detect any outward leakage.
Clean the filter in the suction pipe and/or foot valve at
regular intervals; check performance and absorbed cur-
rent.
The ball bearings in the motor and the ball bearing in the
pump (66.00 - see section 9.2) have permanent lubrica-
tion.
No regreasing is necessary.
See the operating instructions of the motor (if supplied).
Remove any excess grease expelled from the ball-bear-
ing (66.00) after the first period of operation.
In the case of water containing chloride (chlorine or sea
water) the risk of corrosion increases in stagnant water
conditions (also with an increase in temperature and
decrease of pH value). In these cases, if the pump re-
mains inactive for long periods, it must be emptied com-
pletely.
For good measure, as for temporary operation with
dirty liquids, run the pump briefly with clean water to remove
deposits.
Or, after draining, perform the washing operation, insert-
ing clean water (at least 40 litres) into the filling hole (1)
on the delivery side and allowing it to come out of the
draining hole (3) on the suction side (fig.3).
When the pump remains inactive it must be emp-
tied completely if there is a risk of freezing. Remove
both plugs (14.12), (position 3, fig.3).
Before starting the motor again fill the pump completely
with liquid (see section 7.2.) and make sure the shaft is
not jammed by encrustation, sticking of the faces of the
mechanical seal or other causes. In the event that the
shaft cannot be moved by hand, the pump has to be dis-
mantled and cleaned.
Disconnect electrical power before any servic-
ing operation and make sure the pump
cannot be accidentally switched on.
9. Dismantling
Before dismantling, close the gate valves in the suction
and delivery pipes and empty the pump casing (fig. 3).
For dismantling and re-assembly refer to the section
drawing (section 14.) and figures 4, 5.
Dismantling and inspection of all internal parts can be
carried out without removing the pump casing (14.00)
from the pipeline.
Sequence for dismantling MXV-B:
By removing the nuts (61.04) from the tiebolts (61.02) the
motor can be taken out complete (99.00), with all internal
parts of the pump without removing the pump casing (ex-
ternal jacket 14.02) from the pipeline.
Sequence for dismantling MXV(L), MXV(L)4:
1. Mark the position of the motor on the lantern bracket
(32.00), and the position of the lantern bracket on the
upper cover (34.02), ... on the external jacket
(14.02), ... on the pump casing (14.00).
2. Remove the screw (32.32) with the washer (32.31) and
the coupling guard (32.30).
3. Loosen the screws (64.25) of the coupling (64.22).
ATTENTION: to avoid compressing the spring of the me-
chanical seal (36.00) because of axial shifting of the
shaft (64.00), we recommend to loosen the screws
(64.25) of the coupling (64.22) even only for removing
or replacing the motor.
Afterward reposition the shaft (64.00) as indicated in section
10.2.
14