The example (N) value is given for the preferred operating flow region (typically this may extend to 70 to 120 % of the pump best efficiency point); outside the preferred flow region the actual vibration experienced may be multiplied by up to 2.
These standard values can vary with the rotational speed and the power absorbed by the pump. For any special case, do not hesitate to consult us. Measuring vibration at regular intervals will then show any deterioration in pump or system operating conditions.
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| Horizontal |
Vibration Velocity - unfiltered | Configuration | |
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| mm/s (in./s) r.m.s. |
Normal | N | 5.6 (0.22) |
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Alarm | N x 1.25 | 7.1 (0.28) |
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Shutdown Trip | N x 2.0 | 11.2 (0.44) |
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5.5.5 Stop/start frequency
Pump sets are normally suitable for the number of equally spaced stop/starts per hour shown in the table below. Check actual capability of the driver and control/starting system before commissioning.
Motor rating kW (hp) | Maximum stop/starts | |
per hour | ||
| ||
Up to 15 (20) | 15 | |
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Between 15 (20) and 90 (120) | 10 | |
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| |
90 (120) to 150 (200) | 6 | |
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Above 150 (200) | Refer | |
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Where duty and standby pumps are installed it is recommended that they are run alternately every week.
5.6.3 Shutdown > 1 month
a)Isolate motor.
b)Avoid reverse rotation of the pump.
c)Make sure that the discharge line pressure does not reach the foot valve.
d)Close the outlet valve. Eventually close the inlet valve.
e)Switch off external power supply, flushing/quench, cooling liquid.
f)Keep the pump fully filled with water. In case of pumped liquid other than water, drain the pump entirely.
g)Turn once per week the pump shaft of one or two turns.
h)Never restart the pump without carrying out the verifications recommended before starting (see § 5.4.1).
When ambient temperatures are likely to drop below freezing point, the pump and any cooling and flushing arrangements must be drained or otherwise protected.
5.6.4 Restarting in continuous running
a)Ensure that the pump is completely full of liquid.
b)Ensure a continuous supply with a sufficient available NPSH.
c)Ensure a backpressure so that the motor power is not in excess.
d)
Respect the starting frequency imposed by the motor manufacturer.
e)
Protect the pump against water hammer when stopping or starting.
5.6 Stopping and shutdown
According to hydraulic conditions of the installation and its automation degree, stop and restart procedures can have different forms. Nevertheless all of them must respect imperatively the following rules:
5.6.1 Stopping < 1 hour
a)Isolate motor.
b)Avoid reverse rotation of the pump.
c)Make sure that the discharge line pressure does not reach the foot valve.
5.6.2 Stopping < 1 month
a)Isolate motor.
b)Avoid reverse rotation of the pump.
c)Make sure that the discharge line pressure does not reach the foot valve.
d)Close the outlet valve. Eventually close the inlet valve.
e)Switch off external power supply, flushing/quench, cooling liquid.
5.7Hydraulic, mechanical and electrical duty
This product has been supplied to meet the performance specifications of your purchase order, however it is understood that during the life of the product these may change. The following notes may help the user decide how to evaluate the implications of any change. If in doubt contact your nearest Flowserve office.
5.7.1 Specific gravity (SG)
Pump capacity and total head in meters (feet) do not change with SG, however pressure displayed on a pressure gauge is directly proportional to SG. Power absorbed is also directly proportional to SG. It is therefore important to check that any change in SG will not overload the pump driver or over- pressurize the pump.
5.7.2 Viscosity
For a given flow rate the total head reduces with increased viscosity and increases with reduced viscosity.
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