4.2 Delivery pipe
Install a gate valve in the delivery pipe to regulate flow-rate,
head and absorbed power.
Install a pressure gauge between the pump and the gate valve.
ATTENTION
: install a check valve between the pump and the
gate valve in order to avoid reverse flow after switching off the
pump unit and to protect the pump from water hammering.
With servo-operated shut-off devices, provide an air vessel or
other protection device against surge of pressure in the case of
sudden changes of flow rate.
5. Electrical connection
Electrical connection must be carried out only
by a qualified electrician in accordance with local
regulations.
Follow all safety standards.
The unit must be properly earthed (grounded).
Connect the earthing (grounding) conductor to the terminal with
the marking.
Compare the frequency and mains voltage with the name-plate
motor data and connect the supply conductors to the terminals in
accordance with the corresponding diagram inside the terminal box.
ATTENTION
:
never allow washers or other metal parts
to fall into the internal cable opening between the termi-
nal box and stator.
If this occurs, dismantle the motor to recover the object which
has fallen inside.
ATTENTION
: with motor power rating ≥ 5.5 kW avoid direct
starting. Provide a control panel with star-delta starting or an
other starting device.
The motors with supply current directly
switched by thermally sensitive switches can
start automatically.
Install a
device for disconnection from the mains
(switch)
with a contact separation of at least 3 mm in all poles.
With a three-phase motor install a suitable overload cutout in
accordance with the rated current.
Single-phase
MXV-BM
pumps are supplied with a capacitor
connected to the terminals and (for 220-240 V - 50 Hz) with an
incorporated thermal protector.
6. Starting
6.1. Preliminary checks
Make sure the shaft turns freely when rotated by hand.
For this purpose use the screwdriver notch on the shaft end
ventilation side.
6.2. Filling
ATTENTION: never run the pump dry, not even for a short
trial run.
Start the pump after filling it completely with liquid.
When the pump is located above the water level
(suction lift
operation,
fig. 2A
) or with a positive suction head which is too
low (less than 1 m) to open the non-return valve, fill the suction
pipe and the pump through the priming hole (
fig. 3
).
To facilitate this operation use a flexible tube (or elbow) and a funnel.
During filling, the needle screw (14.17) in the drainage plug (14.12)
has to be kept loosened to allow for communication between
the pressure chamber and the suction chamber (
Fig.3a
).
When the liquid level on the suction side is above the pump
(inflow under positive suction head,
fig. 2B
), fill the pump by
slowly and completely opening the inflow gate valve while keeping
the delivery gate valve and air vent hole open to release the air.
During filling, keep the air vent hole open only if
the inflowing liquid presents no possible danger
on account of its nature, temperature or pressure.
With a delivery pipe arranged horizontally, or lower than the pump,
keep the delivery gate valve closed during the filling operation.
6.3. Starting and checking operations
Tighten the needle screw (14.17) in the drainage plug (14.12)
(
fig. 3b
) and close the air vent hole (14.04).
Start the pump with the delivery gate valve closed and with the
suction gate valve fully open. Immediately afterwards, gradually
open the delivery gate valve, adjusting the point of operation
within the limits indicated on the name plate.
With a three-phase motor, check that the direction of rota-
tion is as shown by the arrow on the external jacket (14.02):
i.e. clockwise when viewing the motor from the fan end for
MXV-B 25-32-48. i.e. counter-clockwise when viewing the
motor from the fan end for MXV-B 50.
Otherwise disconnect electrical power and reverse the connec-
tions of two phases.
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, despite
opened gate valves) or if a pressure oscillation is indicated on
the pressure gauge, make sure all the suction pipe couplings
are perfectly sealed and tighten the needle screw in the
drainage plug (
fig. 3b
).
ATTENTION: when the pump is located above the water
level
(suction lift operation,
fig. 2A
),
after a long idle peri-
od, before restarting the unit, check that the pump is
still filled with liquid and vented.
Otherwise, check for proper operation (opening and closing) of
the foot valve and fill the pump with liquid.
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
3
/h for
MXV-B 25-2
; 0.5 m
3
/h for
MXV-B 32-4
; 1 m
3
/h for
MXV-B 40-8
; 1.6 m
3
/h for
MXV-B 50-18
.
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 surface temperature is higher than 80 ˚C.
7. 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.
The special funnel-shaped lantern bracket is designed to con-
tain 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 current.
The ball bearings in the motor have permanent lubrication. No
regreasing is necessary.
See the operating instructions of the motor (if supplied).
Remove any excess grease expelled from the ball-bearing
(66.00) after the first period of operation.
4.93.306
14.12
14.17
6
Filling and
air vent 14.04
Fig.3a Filling:
Fig.3b Operating:
internal passage open
internal passage closed
