Installation and operating instructions Wilo
–
SCPV pumps
18
The converter should never generate voltages
peaks to the motor connection higher than
850V and deliver voltages variations
Δ
U/
Δ
t
greater than 2500 V/
μ
s.
If the above conditions cannot be fulfilled, an
appropriate filter should be place between the
frequency converter and the motor. Please
contact the frequency converter manufacturer
for guidance in the selection of this filter.
Strictly follow the Frequency converter
manufacturer instructions.
The minimum rotation speed of the pump
should never go below 40% of the nominal
speed.
8 Commissioning
W ARNING! Danger of injury
The devices whether on pump/motor/electrical
panels must never be dismantled or disabled. They
must be checked by an authorized technician for
proper functioning before, start-up. Refer to
motor & electrical panel instruction manuals for
electrical safety & control devices information.
WARNING! Danger of pump damage!
Do not operate the pump away from specified
operating range. Operating beyond duty point may
not pose a risk to the operator but will reduce the
efficiency of the pump or damage the pump itself.
Operation more than 5 minutes, at close valve
condition is not recommended. For hot liquids this
is not recommended at all. Ensure that always site
NPSH-A is more than NPSH-R.
8.1 Cleaning prior to start
8.1.1 Pipe work flushing
Before the pumps are brought into service, either
on initial commissioning or on re-commissioning
after overhaul, the pipe work associated with the
pumps must be flushed through. This will clear
deposits or scales which may have accumulated in
the pipes, and which could damage the internal
components of the pumps.
8.1.2 Cleaning of bearings
Where possible, especially if the unit has been in
store for a long period before commissioning, the
bearings should be cleaned and flushed out with
clean white spirit or good quality paraffin. Waste
should not be used for this purpose, as particles
of foreign matter may be left behind which would
cause damage when the bearing is in service. No
need to clean ZZ bearings.
Bearings should be then filled with recommended
grade and quality of fresh lubricant.
8.2 Filling and venting
Fill and vent the system correctly, through air
cock. Brief dry running will damage the pump.
Please also note that these pumps are not self
priming, which means that the impeller & casing
must always be fully filled with fluid to be handled
before putting in operation
WARNING! Danger of injury!
There is a risk of burns if the pump is touched! The
entire pump may become very hot; depending on the
operating state of the pump or system (fluid
temperature).
CAUTIO N! Danger sealing system damage!
Any attempt to run the pump dry or partially full may
result in seizure of the rotating internal components.
8.2.1 Pumps operating on flooded suction head
When these pumps operate on a positive suction head,
all that is required to prime them is to open the air
release valve situated on top of the pump casing, open
the pump inlet isolating valve and vent the air out of
the casing. When the liquid issues from the air vent,
free of air, the pump is properly primed. The air vent
must be closed after priming and before the pumping
set is started.
8.2.2 Pumps operating on negative suction head
There are two methods of priming pumps that draw
their liquid from an elevation lower than the pump
inlet branch:
If the inlet pipe work is fitted with a non-return
foot valve, the pump casing and inlet pipe work can
be filled with liquid from an external source under
pressure. The pressure imposed on the pump by
this method must not exceed that for which the
pump is designed. In certain cases priming can be
achieved by flooding back from the delivery side of
the pump.
By extracting air or gas from the pump casing. To
enable this method to be used, the gland
arrangement must be sufficiently air-tight or it
should be liquid sealed from an external supply. For
operation details of gas exhausts reference should
be made to the manufacturer
’s
instructions. Some
form of priming indicator is usually fitted to indicate
when the priming operation is complete.
8.2.3 Pumps operating on hot liquids
Pumps operating on hot liquids are usually so
arranged that the liquid flow into the pump is under
pressure. If the saturation pressure of such liquids is
above atmospheric pressure, any attempt to prime
the pump will result in the liquid "flashing" from the
air cocks. For these reasons, the air cocks at the top
of the pump casing should be left slightly open
when priming boiler circulating pumps until air has
been driven out of the casing completely.
The cooling water services of a pump handling hot
liquids should be turned on before the pump is
primed. These services may supply cooling water to
the bearings and / or stuffing boxes. Where the
services are functioning, open the inlet valves and
start warming the pump throughout. Never cut off
the water services while the pump is "on
temperature". Where bearings are water-cooled,
adjust the cooling water supply until the bearings
have a running heat. Over-cooling may lead to
condensation of moisture from the atmosphere
inside the bearing with consequent contamination
of the oil. The suction valve, if provided, must be
fully open and the delivery valve must be closed.
