Xylem GEN series firefighting booster sets - Manuale (Pagina 29)

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- When the pressure drops to the P1 value
the first pump starts.
- If the pressure drops to the P2 value the
second pump starts.
The pump can only be stopped manually by
operating the controls on the electric panel.
The pump stops only if the system pressure
has been restored to the P1s value. In the
version with automatic shut-off, the pumps
stop automatically after the system pressure
has been restored for a set time.
Pressure switch
The pressure switches are set at the factory
according to a set of values that depend on
the type of pump. The settings are shown on a
plate attached to the set or the control panel,
or enclosed in the documentation.
In order to modify the settings according to
the system’s hydraulic conditions, make
adjustments to the pressure switch:
1 Ps stop pressure
2 Ps-P differential pressure
6. Start-up
To start the set, proceed as follows:
a. Connect the water supply.
b. Connect the power supply.
c. Check the pre-charge value of the tank.
d. Shut off the pump’s delivery valves.
e. Prime the set (see pumps’ handbook) and the suction manifold.
f. Connect the power supply via the panel switch and set the unit to manual mode.
g. Start the first pump.
h. For three-phase versions, check the rotation direction. If it is incorrect, exchange two
power supply phases.
i. Open the pump delivery valve slowly and bleed the air.
j. Repeat the above operations for the other pumps.
k. Set the unit to automatic operation.
Setting a new value
In order to modify the settings within the maximum pressure limits of the pumps and/or
system, after performing the start-up operations proceed in the following manner for each
pump:
a. Adjust the activation (P start) and deactivation (P stop) pressures for each pair of
pressure switches.
P
1
P2
P1
s
P2
s
H
Q
Fig. 3
Pmax
G20_
0003_
A
_S
C
1
2
G
2
0
_
0
0
0
4
_
A
_
S
C
P1s
P2s
P1
P2