5.5 Running the pump
5.5.1 Venting the pump
Vent the pump to enable all trapped air to escape taking due care with hot or hazardous liquids.
SAFETY INSTRUCTIONS WHEN THE PUMP IS RUNNING:
If hot or freezing components of the machine can present a danger to operators, they must be shielded to avoid accidental contact. If a 100 % protection is not possible, the machine access must be confined to the maintenance staff only.
Under normal operating conditions, after the pump has been fully primed and vented, it should be unnecessary to
If the temperature is greater than 80 °C (176 °F), a warning plate must be clearly placed on the pump.
5.5.2 Pump fitted with a stuffing box
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 pressurized. 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 restarted. When the pump is restarted it should be checked to ensure leakage is taking place at the packed gland.
When adjusting an operating stuffing box (shield grids removed for this operation), the operator must be very careful. Safety gloves are compulsory and loose clothes are not allowed (above all to the arms) to avoid being caught by the pump shaft.
The pump should be run for ten minutes with steady leakage and the gland nuts tightened by 10 degrees at a time until leakage is reduced to an acceptable level.
The temperature of the gland should be checked after each round of tightening. If the temperature starts to climb rapidly then back off the gland nuts until the temperature drops down. Wait for the temperature to stabilize before tightening again. The leakage must not be reduced below a rate of 20 drops per minute. Bedding in of the packing may take several hours.
Shield grids being removed during installation of the gland packing, it must be ensured that they are replaced as soon as this operation is completed.
It is strictly forbidden to open switch cupboards, switch boxes, or all other live electric equipment. If it is necessary to open them in order to take readings, to carry out tests or adjustments for example, only a skilled technician may do them with adapted tools. Make sure that physical protection against electrical risks are used.
5.5.3 Bearings
If the pumps are working in a potentially explosive atmosphere, temperature or vibration monitoring at the 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
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.
5.5.4Normal vibration levels, alarm and trip For guidance, pumps generally fall under a classification for rigid support machines within the International rotating machinery standards and the recommended maximum levels below are based on those standards.
Alarm and trip values for installed pumps should be based on the actual measurements (N) taken on site on the bearing housings of the pump in the fully commissioned as new condition.
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