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Beschikbare talen
Beschikbare talen
Example 3: installation at sea level and fluid at t = 90°C
required N.P.S.H. :
3.25 m
pb :
10.33 mcw
Hr:
2.04 m
t:
90°C
pV:
7.035 m
Z1
10.33 - 3.25 - 2.04 - 7.035 = -1.99 approx.
In the last case, in order to operate correctly the pump must be fed with a positive head of 1.99 - 2 m, that is the free surface of
the water must be 2 m higher than the axis of the pump.
N.B.: it is always good practice to leave a safety margin (0.5 m in the case of cold water) to allow for
errors or unexpected variations in the estimated data. This margin becomes especially important with
liquids at a temperature close to boiling point, because slight temperature variations cause considerable
differences in the working conditions. For example in the third case, if instead of 90°C the water
temperature reaches 95°C at any time, the head required by the pump would no longer be 1.99 but 3.51
metres.
7.4.
Connecting auxiliary systems and measuring instruments.
The realization and connection of any auxiliary systems (washing liquid, seal cooling fluid, dripping liquid) must
be considered when designing the system. These connections are necessary for better and longer lasting pump
operation.
In order to ensure continuous monitoring of the pump functions, it is recommended to install a vacuum pressure
gauge don the intake side and a pressure gauge on the delivery side. To check the motor load the installation of an
ammeter is advised.
8.
ELECTRICAL CONNECTION
Caution: always follow the safety regulations!
Scrupulously follow the wiring diagrams inside the terminal board box and
those on page 4 of this manual.
8.1.
The electrical connections must be made exclusively by skilled personnel (see paragraph 6.1) as required by
the safety regulations in force.
The requirements of the electric energy supply company must be scrupulously complied with.
In the case of three-phase motors with star-delta start, ensure that the switch-over time from star to delta is as short
as possible and that it falls within table 8.1 on page 118.
8.2.
Before opening the terminal board and working on the pump, ensure that the power has been switched off.
Check the mains voltage before making any connection. If it is the same as the voltage on the data plate, proceed
8.3.
to connect the wires to the terminal board, giving priority to the earth lead.
8.4.
ENSURE THAT THE EARTH SYSTEM IS EFFICIENT AND THAT THERE IS THE POSSIBILITY OF
MAKING A GOOD CONNECTION.
8.5.
The pumps must always be connected to an external switch.
The motors must be protected with special remote-control motor-protectors calibrated for the current shown on the
8.6.
plate.
9.
STARTING UP
9.1.
Before starting the pump, check that:
-
-
-
-
10.
STARTING/STOPPING
10.1.
STARTING
Fully open the gate valve on intake and keep the one on delivery almost closed.
10.1.1.
10.1.2.
Switch on the power and check that the motor is turning in the right direction, that is clockwise when viewed from
the fan side. This check must also be performed after having fed the pump, activating the main switch with a fast
start-stop sequence. If the motor is turning in the wrong direction, invert any two phase leads, after having
disconnected the pump from the mains.
the pump has been properly primed, filling the pump body completely. This ensures that the
pump immediately starts to work regularly and that the seal (mechanical seal or stuffing box
seal) is well lubricated. Dry operation causes irreparable damage to the mechanical seal and
the stuffing box seal.
the auxiliary circuits have been correctly connected;
all the moving parts have been protected with suitable safety systems;
the electrical connection has been made as indicated previously;
ENGLISH
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