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Section 6.....................................................Commissioning and Operation
8. PUMPS FITTED WITH MECHANICAL SEAL
a) Before pumping dirty liquids it is advisable, if possible, to run in the pump mechanical seal using
clean liquid to safeguard the seal face.
b) External flush or quench should be started before the pump is run and allowed to flow for a period
after the pump has stopped.
c) Never run a mechanical seal dry, even for a short time.
9. STOP / START FREQUENCY
This depends on the driver manufacturers' recommendation. Check actual capability of the driver and
control/starting system before commissioning.
10. DURING RUNNING THE PUMP
Check the following and regulate, if necessary
a) The pump is running smooth.
b) The flow of sealing liquid (if external liquid is provided for sealing purpose) is uninterrupted.
c) If packed gland is used, Leakage through stuffing box is normal. There should be leakage of 60-80
drops per minute.
d) The bearings are not getting heated up excessively.
e) Head and capacity developed by the pump is as specified.
f) Power consumption is within the limit.
g) Ensure that there is no mechanical friction in the pump.
h) Check suction and discharge pressure gauges.
i) Check for excessive leakage at seal areas.
j) Check for unusual noises.
k) Check for vibrations.
l) Stop the pump immediately, if any defects are noticed. Do not start the pump unless the defects
are rectified. Report immediately to the supplier if it is not possible to rectify the defects.
11. STOPPING AND SHUTDOWN
a) The centrifugal pumps can be shut down by switching off the power to the motor, with open or
closed flow regulating valve. If there are no provisions against water hammer, it is recommended
to close the flow regulating valve at pump discharge prior to stopping the pump, but ensure that
the pump runs in this condition for no more than a few seconds.
b) Avoid the use of instantaneous shut-off valves, such as solenoid valves. These can cause
severe pump damage.
c) If a non-return valve is not fitted, or the isolating valve at the discharge side is not completely
closed, it may happen that during the shut-down the pump shaft will rotate in the opposite
direction than is normal: in such cases absolutely avoid restarting the pump until the pump shaft
has stopped rotating.
d) After the first start-stop and if necessary, check pump/motor alignment and make sure that no
external forces or moment rest on pump or piping.
e) In the event the pump is shut down for an extended period of time it is recommended to
completely drain the pump to prevent the possibility of freezing in the winter time and/or the
possibility of corrosion due to stagnant liquid left in the pump.
ISO PRO Centrifugal Pump
27
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