Pratissoli MK2 Serie Manual De Uso Y Mantenimiento página 53

17.1.4 Dimensions and weight
For the dimensions and weight of the pumps, refer to the
diagrams in chapter 6.
17.1.5 Pump supply
The pumps must always be installed with a suction head,
that is they must receive the water by gravity or by forced
feeding, but never draw it from a lower level.
The pumps are able to withstand minimum suction heads of
even 1 metre, however, for the best volumetric efficiency and
above all to avoid cavitation, the available positive suction
head (NPSH avail) measured at the suction flange in the head
must be equal to or greater than the values below.
NPSH
MK2R/MK2SR40 4.5
MK2R/MK2SR45
5.5
MK2R/MK2SR50 6.5
MK2R/MK2SR55
7.5
MK2R/MK2SR60 8
MK2R/MK2SR65
9
For the greater displacements, of the pumps with piston
Ø 55 - 60 - 65, forced feeding by a booster pump is highly
recommended in order to avoid cavitation, considering the
geometry of the hydraulics and the considerable flow rates.
The booster pump must have at least twice the flow rate of the
rated flow rate of the plunger pump and pressure of between
2 and 3 bar.
These supply conditions must be observed at all operating
speeds.
The booster pump must always be started up
before the plunger pump.
It is advisable to install a pressure switch on the
supply line downstream of the filters protecting
the pump.
17.1.6 Filtration
Our technical or customer service departments are at the disposal of our customers in order to define the system better; by way
of example, we provide the following layouts (Fig. 12 and Fig. 12/a).
With a manually activated control valve
Inlet
Supply tank
User specific lay-out
(m)
r
53
1 Filter 6 Safety valve
2 Pressure gauge 7 Accumulator
3 Pressure switch 8 Control valve
4 Plunger pump
5 Pressure gauge
Bypass
Fig. 12