Lowara 10HM02P11T, Инструкция по установке и эксплуатации, Страница: 7 / 76

6
5. Operation
The converter features a power and control board connected by a cable directly to the terminal
board of the pump’s motor. All this is encapsulated between a base and an aluminium casing with
a finned top to ensure heat dissipation. Three warning lights signal the status of the converter:
POWER: Linea ; RUN: Marcia; ALARM: Allarme
A connection via serial interface allows the two variators in the pressure booster unit to converse
with each other and provide for the cyclic starting and stopping of the pumps based on user
demand.
A pressure set point must be established; then, once the unit has been installed, the entire system
will adapt to this value.
The pressure transmitters, located on the delivery side, put out a signal which is proportional to the
system pressure value. The drop in system pressure determined by the users' water consumption
causes a decrease in the value of the signal that, through the variator, starts the first pump,
regulating its speed so as to re-establish the pressure set point (operating pressure).
If the capacity of the pump is lower than the quantity of water drawn, the pressure continues to
drop until the first pump reaches the maximum operating speed and transmits a signal to the
second pump to start.
The first pump continues to run at maximum speed while the second pump modulates its operation
to meet the water demand.
If the pressure increases due to decreased water consumption, the signal from the transmitters
increases causing the pumps to stop (inverted order of the starting sequence)
.
In order to distribute the working hours and reduce the number of starts per hour of each pump, the
program switches the starting order of the pumps at each start-up.
6. Installation
The unit must be protected from the weather and especially from freezing temperatures.
The operating conditions described in our catalogue provide for the water to be supplied by a water
storage tank, with the liquid level at the same height as the suction manifold.
Whenever possible, the unit should be installed with a positive suction head, i.e. with the pump
suction port located below the minimum water level.
If the above conditions cannot be ensured the installation is described as suction lift. In this case
the suction flow resistance, suction lift and NPSH of the pumps must be taken into account.
When in doubt, please contact our technical service department.
DANGER
WARNING
DANGER
RISK OF ELECTRIC
SHOCK
DANGER
WARNING
DANGER
RISK OF ELECTRIC
SHOCK
7
The unit should be installed as close to the water source as possible.
Bends in the connection pipe to the suction manifold should be few and wide and have a positive
gradient (i.e. from below to the pumps positioned higher up).
Avoid the formation of siphons.
The suction pipes and foot valve must be of adequate size to prevent excessive flow resistance
and the consequent cavitation phenomena.
In any case, the diameter of the pipe must not be smaller than the diameter of the unit’s manifold.
Make sure there are no air infiltrations in the suction pipe.
Except in the case of installation with positive suction head, a foot valve is usually necessary.
The surge tank must be mounted between the pressure booster unit and the user. The volume of
the surge tank should be approximately 5% of the maximum capacity (l/min) of a single pump (also
for multiple pump systems), for a minimum of 8 litres.
For the same reason, when the unit serves a large water distribution network (big condominiums,
industrial plants, etc.), we recommend the installation of a diaphragm expansion tank immediately
before the check valve.
A vibration-damping joint should be installed on the delivery manifold to prevent the transmission of
vibrations to the system and undue stress.
We recommend that you install an on-off valve immediately after the unit.
We recommend that you install a cock for testing the unit if no tap has been provided near the unit.
In case of connection to the municipal water system, make sure that the maximum pressure of the
water system plus that of the pump does not exceed the maximum value allowed for the pump.
For units equipped with diaphragm tanks, the precharge pressure of the tanks must be checked
periodically to make sure that it is about 0.2 bar lower than the working pressure of the unit.
This check must be made while the system is shut down and depressurised, with at least one tap
open, or with the tank disconnected from the system.
7. Filling the Unit with Water
CAUTION: the pump must be filled with water before it is started. Dry running would cause
damage to the mechanical seal and impeller.
CAUTION: the pump can be damaged if it is left full of water and inactive in environments with
temperatures below freezing.
DANGER
WARNING