PVML USER INSTRUCTIONS ENGLISH 00079591 – 01/05
®
5.6.1 Suction pressure above atmospheric
pressure
the seal flush line at the mechanical seal/stuffing box
to allow the trapped air to escape. Let liquid run out
until free from air bubbles.
De-aerate the pump via the chamber of the
mechanical seal or via the flange of a pipe connected
to the mechanical seal
5.7 Starting the pump
a)
Ensure flushing and/or cooling/
heating liquid supplies are turned ON before starting
the pump.
b) CLOSE the outlet valve.
c) OPEN all inlet valves.
d) Prime the pump.
e)
Ensure all vent connections are closed
before starting.
f) Start motor and check outlet pressure.
g) If the pressure is satisfactory, slowly OPEN outlet
control valve.
h)
Do not run the pump with the outlet
valve closed for a period longer than 30 seconds.
i) If NO pressure, or LOW pressure, STOP the
pump. Refer to section 7,
Faults; causes and
remedies
, for fault diagnosis.
5.8 Running the pump
5.8.1 Venting the pump
Vent the pump through the mechanical seal
again, to enable all trapped air to escape taking due
care with hot or hazardous liquids.
Under normal operating conditions, after the pump has
been fully primed and vented, it should be
unnecessary to re-vent the pump.
5.8.2 Pumps fitted with packed gland
If the pump has a packed gland there must be some
leakage from the gland. Gland nuts should initially be
finger-tight only. Leakage should take place soon
after the stuffing box is pressurised.
The gland must be adjusted evenly to give visible
leakage and concentric alignment of the gland ring to
avoid excess temperature. If no leakage takes place
the packing will begin to overheat. If overheating
takes place the pump should be stopped and allowed
to cool before being re-started. When the pump is re-
started, check to ensure leakage is taking place at the
packed gland.
If hot liquids are being pumped it may be necessary
to slacken the gland nuts to achieve leakage.
The pump should be run for 30 minutes with steady
leakage and the gland nuts tightened by 10
degrees at a time until leakage is reduced to an
acceptable level, normally a minimum of 120 drops
per minute is required. Bedding in of the packing
may take another 30 minutes.
Care must be taken when adjusting the gland
on an operating pump. Safety gloves are essential.
Loose clothing must not be worn to avoid being
caught up by the pump shaft. Shaft guards must
be replaced after the gland adjustment is complete.
Never run gland packing dry, even
for a short time.
5.8.3 Pumps fitted with mechanical seal
Mechanical seals require no adjustment. Any slight
initial leakage will stop when the seal is run in.
Before pumping dirty liquids it is advisable, if
possible, to run in the pump mechanical seal using
clean liquid to safeguard the seal face.
External flush or quench should be
started before the pump is run and allowed to flow
for a period after the pump has stopped.
Never run a mechanical seal dry,
even for a short time.
5.8.4 Bearings
If the pumps are working in a potentially
explosive atmosphere, temperature or vibration
monitoring at the motor bearings is recommended.
If bearing temperatures are to be monitored it is
essential that a benchmark temperature is recorded
at the commissioning stage and after the bearing
temperature has stabilized.
•�
Record the bearing temperature (t) and the
ambient temperature (ta)
•�
Estimate the likely maximum ambient
temperature (tb)
•�
Set the alarm at (t+tb-ta+5)
°
C [(t+tb-ta+10)
°
F]
and the trip at 100
°
C (212
°
F) for oil lubrication
and 105
°
C (220
°
F) for grease lubrication
It is important, particularly with grease lubrication,
to keep a check on bearing temperatures. After
start up the temperature rise should be gradual,
reaching a maximum after approximately 1.5 to 2
hours. This temperature rise should then remain
constant or marginally reduce with time. (Refer to
section 6.1.1 for further information.)
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