Automatic Monitoring Devices; Checking Of Operation; Service Manuals - Grundfos BM 4 Instrucciones De Instalación Y Funcionamiento

Recommended pressures
Inlet pressure
Size Min.
[bar] [p.s.i.] [bar] [p.s.i.]
BM 4" 0.5 7.25 60
BM 6" 0.5 7.25 50
BM 8" 1 14.5 25
BMB 4" 0,5 7.25 30
BMB 6" 0,5 7.25 20
BMB 8" 1 14.5 10
* Note: If the maximum inlet/outlet pressure is exceeded, install a
safety valve.
Maximum permissible liquid temperature
Maximum
liquid
Motor
temperature
°C
GRUNDFOS 4" 40
GRUNDFOS 6" 40
FRANKLIN 8" 30

9. Automatic monitoring devices

To protect the pumps against dry running and to ensure a mini-
mum flow of cooling water past the motors, the system must be
fitted with flow and pressure monitoring devices (figs. 4 to 7).
A pressure switch on the suction side is dimensioned in accord-
ance with the estimated inlet pressure. At a pressure lower than
0.5 bar for BM 4", BM 6", BMB 4" and BMB 6" and 1 bar for BM 8"
and BMB 8", an alarm is given and shortly after the pumps will
stop.
All discharge connections to the system should be fitted with flow
switches which will stop the system at the set minimum flows.
The above monitoring devices ensure a correct inlet pressure and
a minimum flow of cooling water past the motor.
Flow switch cutting-in is adjusted for a minimum time delay equiv-
alent to the maximum starting frequency of the system.

10. Checking of operation

Depending on the number of operating hours of the pumps, the
following should be checked at suitable intervals:
1. Flow.
2. Starting frequency.
3. Control and protective devices.
4. Liquid temperature.
5. Minimum flow through modules during operation.
If any of the above checks reveal any abnormal operating details,
inspection should be carried out in accordance with the fault find-
ing chart.
Outlet pressure
Max.* Max.*
[bar] [p.s.i.]
870 80 1160
725 80 1160
362 70 1015
435 60 870
290 50 725
145 35 507.5
Minimum
flow velocity Minimum
past the flow
motor
m/s m³/h
≥ 0.15 ≥ 0.8
≥ 0.15 ≥ 5.5
≥ 0.16 ≥ 18.5

11. Service manuals

For the replacement and repair of parts of the booster unit,
please refer to:
1. Service Manual for Replacement of Motor Cable and Motor
(4", 6" and 8").
2. Parts Lists with instructions for dismantling and assembly of
pump and motor.
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