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English (US)
14. Maintenance
14.1 Pumps
The internal pump parts are maintenance-free. It is important to
keep the motor clean in order to ensure adequate cooling of the
motor. If the pump is installed in dusty environments, it must be
cleaned and checked regularly. Take the enclosure class of the
motor into account when cleaning.
The motor has maintenance-free, greased-for-life bearings.
14.2 CU 323
The CU 323 is maintenance-free. It must be kept clean and dry.
Protect it against direct sunlight. Furthermore, the CU 323 must
not be outside the ambient temperature range. See section
15. Frost protection
Pumps which are not being used during periods of frost should be
drained to avoid damage. Follow the instructions below:
1. Close the isolating valves before and after the pump.
2. Remove the filling and drain plugs.
3. Remember to open the isolating valves and refit the plugs
before the pump is put into operation again.
Do not fit the filling and drain plugs until the pump is to be used
again.
16. Taking out of operation
Switch off the main switch to take the booster system out of
operation.
Individual pumps are taken out of operation by switching off the
corresponding motor-protective circuit breaker, automatic circuit
breaker or fuse.
17. Technical data
17.1 Pressure
Inlet pressure
Calculation of the inlet pressure is recommended in these cases:
•
Water is drawn through long pipes.
•
Inlet conditions are poor.
To avoid cavitation, make sure that there is a minimum inlet
pressure on the suction side of the booster system. The minimum
inlet pressure in psi can be calculated as follows:
H
= P
b
- NPSH - H
f
- H
v
- H
s
P
b
= Barometric pressure in feet (33.9 feet at sea level). In
closed systems, p
b
indicates system pressure in feet.
H
f
= Friction loss in suction piping in feet. (At the highest flow
the pump will be delivering.)
H
v
= Vapor pressure in feet.
NPSH = Net Positive Suction Head in feet.
NPSH can be read from the NPSH curve at the maximum capacity
at which the pump will run.
(See Grundfos CM, CME Data booklet 98435269 / L-CM-PG-001).
H
s
= Safety margin = minimum 2 feet.
If "H" is calculated as positive, the pump can operate at a suction
of maximum "H" feet. If "H" is calculated as negative, an inlet
pressure (psia) of minimum "H" feet is required.
Maximum inlet pressure
The actual inlet pressure plus the pressure when the pump is
operating against a closed valve should always be lower than the
maximum system pressure.
Operating pressure
As standard, the maximum operating pressure is 145 psi (10 bar).
17.2 Temperature
Liquid temperature: +32 °F to +140 °F (0 °C to +60 °C).
Ambient temperature: +32 °F to +104 °F (0 °C to +40 °C).
17.3 Relative humidity
Maximum 95 %.
Warning
Before starting work on the pumps, make sure
that the power supply has been switched off.
Lock the main switch with a padlock to ensure
that it cannot be accidentally switched on.
Warning
Ensure that the escaping water does not cause
injury to persons or damage to the motor or other
components.
In hot-water installations, special attention
should be paid to the risk of injury caused by
scalding hot water.
Warning
The conductors in front of the main switch are
still energized. Lock the main switch with a
padlock to ensure that it cannot be accidentally
switched on.
Caution
A positive inlet pressure is required before start-
up and during operation.
Note
Note
Flooded suction and suction lift applications are
possible on some, but not all, Multi-B systems.
Special attention must be applied to confirm inlet
conditions (NPSH
A
) is greater than NPSH
R
at the
maximum capacity at which the pump will run.
Note
Note
In this manual, the term ‘inlet pressure’ is defined
as the pressure/vacuum which can be measured
immediately before the booster system.
