Installation and operating instructions WILO Mather and Platt – VT pumps 33
10.3 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).
CAUTION! Danger sealing system damage!
Any attempt to run the pump dry or partially full may
result in seizure of the rotating internal components.
10.3.1 Availability of liquid
Efficient operation of the pump depends upon fine running
clearance that is lubricated by the pumped fluid. Sufficient
fluid must be available to ensure that the pump is flooded
at all times to prevent seizure of the internal components.
Wherever external flushing/lubrication is provided it should
be available before starting the pump.
If on starting, a pump fails to generate at its rated delivery
head, as indicated on the pump nameplate, it must be
stopped immediately; the cause must be ascertained and
rectified, before re-starting.
Ensure that minimum submergence is available as
recommended. Open all ancillary inlet and outlet isolating
valves such as, bearing cooling systems, gland sealing, or
cooling systems, air vents, leak-off connections etc. The
efficient operation of a centrifugal pump depends upon fine
running clearances, which are lubricated by the pumped
liquid. These pumps must therefore be properly primed
before starting, with venting of all the air, gases, vapor etc.
10.3.2 Pumps handling hot liquids
Pumps handling 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
hot media 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 delivery valve must be in closed condition.
10.4 Starting the pump
10.4.1 Direction of rotation
Disconnect the drive coupling and run the motor to check its
direction of rotation. A directional arrow is provided on the
pump unit.
10.4.2 Pre-starting checks
• Check that sufficient submergence level is maintained.
• Check that there is no blockage in the strainer at the suction
bell end.
• Check for free rotation of the unit when coupled.
• Check that delivery pressure gauge is connected.
• Check that discharge line is having non-return valve & get
valve installed.
• Test and make available all protection devices like alarm,
signals, interlock systems incorporated in the auxiliary and
main pumping control system.
• Ensure that all electrical checks on motor, relay setting in
panel etc. have been carried out in accordance with the
instructions of motor manufacturer.
• Ensure that cooling water arrangement is provided bearing
cooling and stuffing box.
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