Frequency Of Starts And Stops; Automatic Monitoring Devices; Checking Of Operation - Grundfos BM Serie Instrucciones De Instalación Y Funcionamiento

The pressure limits stated in the table below must be observed.
Recommended pressure
Inlet pressure
Type Min.
[bar] [psi] [bar]
BM 4" 0.5 7.25 60
BM 6" 0.5 7.25 60
BM 8" 1 14.5 60
BMhp 6" 0.5 7.25 80
BMhp 8" 1 14.5 80
1)
Contact Grundfos if higher pressures are required.
2)
Note that if the maximum inlet/outlet pressure is exceeded,
install a safety valve.
3)
Only for the R-version. For other versions, 50 bar applies
4)
Only for the R-version. For other versions, 25 bar applies.
10.1.1 Cooling
The temperature and flow limits stated in the table below must be
observed to ensure sufficient cooling of the motor.
Maximum permissible liquid temperature
Maximum
liquid
Motor
temperature
[°C] [°F]
Grundfos 4" 40 104
Grundfos 6" 40 104
Grundfos 8" 40 104
10.1.2 Flushing of the booster module
When a module is flushed, the flow rate must be reduced to
maximum 10 % of the rated flow at a minimum pressure of 2 bar.
The modules must be stopped while the system is flushed. See
section 10. Operation.
When pumping water with a salinity above 2000 ppm
NaCl, the module must be flushed through in the flow
direction as described in the following.
The flushing procedure depends on the operating condition:
• Intermittent operation
If the booster module has to be stopped for more than 30
minutes, it must be flushed through with clean freshwater for
approximately 10 minutes. The flushing must be continued
until the module is completely filled with clean freshwater. The
salinity of the flush water must be below 500 ppm on the outlet
side.
• Continuous
• Operation
BM: Once every 24 hours, the module must be stopped and
flushed through with the pumped liquid by means of the feed
pump.
BMhp: Due to an internal bypass, it is not necessary to stop
the BMhp booster modules every 24 hours.
• Interruption of operation
In case of power, pump or motor failure, the booster module
must be cooled and flushed through with clean freshwater.
The drain plug can be used when flushing the booster module.
The booster module can also be disconnected, removed,
dismantled and cleaned with clean freshwater.
12
1)
Outlet pressure
2) 2)
Max. Max.
[psi] [bar] [psi]
3)
870 80 1160
3)
725 80 1160
4)
362 70 1015
725 80 1160
362 80 1015
Minimum
flow velocity Minimum flow
past the rate
motor
3
[m/s (ft/s)] [m /h (US GPM)]
≥ 0.15 (0.49)
≥ 0.8 (3.5)
≥ 0.15 (0.49)
≥ 5.5 (24)
≥ 0.15 (0.49)
≥ 18.5 (81.5)

10.1.3 Frequency of starts and stops

Minimum 1 per year is recommended.
Maximum 20 per hour.
Maximum 100 per day.
8" modules: Maximum 20 per day.

11. Automatic monitoring devices

To protect the modules against dry running and to ensure a
minimum flow rate of cooling water past the motors, the system
must be fitted with flow and pressure monitoring devices (figures
6 to 9).
The pressure switch on the inlet side is set in accordance with the
estimated inlet pressure. At a pressure lower than 0.5 bar for BM
4" and BM/BMhp 6", and 1 bar for BM/BMhp 8", an alarm is given
and the module must be stopped without delay.
All outlet connections to the system must be fitted with a flow
switch which will stop the system at the set minimum flow rates.
The above monitoring devices ensure a correct inlet pressure and
a minimum flow rate of cooling water past the motor.
If the modules are stopped automatically, we recommend
automatic flushing. See section
module.

12. Checking of operation

Depending on the number of operating hours of the modules, the
following must be checked at suitable intervals:
• flow
• starting frequency
• control and protective devices
• liquid temperature
• minimum flow rate through modules during operation.
If any of the above checks reveal any abnormal operating details,
inspection must be carried out in accordance with section
13. Fault finding the product.
We recommend to use the log book at the end of these
instructions.
10.1.2 Flushing of the booster