Pump Supply; Suction Line; Filtration - Pratissoli KV Serie Manuel D'utilisation Et D'entretien

9.5

Pump supply

KV pumps require a positive suction head (NPSHr) of between
5 and 7 bar measured at the head inlet.
The booster supply pump must have the following features: at
least twice the flow rate of the plunger pump's rated flow rate
with a minimum pressure of 5 bar.
These supply conditions must be observed at all operating
speeds. The operation of the booster pump must be
independent from that of the plunger pump.
The booster pump must always be started before
the plunger pump.
It is advisable to install a pressure switch on the
supply line downstream of the filters protecting
the pump.
9.6

Suction line

For smooth operation of the pump, the suction line must have
the following characteristics:
1. Minimum internal diameter as indicated in the graph in
par. 9.9 and in any case equal to or exceeding that of the
pump head.
Localized restrictions should be avoided along the
piping, as these can cause pressure drops resulting
in cavitation. Avoid 90° elbows, connections with
other piping, restrictions, reverse gradients, inverted
U-curves and Tee connections.
9.7

Filtration

The permissible filtration for this series of pumps must be max. 20 μ (micron). It is normally obtained with a bank of at least three
filters, positioned as shown in Fig. 7.
Inlet
Supply tank
Drain
The filters must be installed as close as possible to the pump,
be easy to inspect and have the following characteristics:
1. Minimum flow rate at least 3 times the nominal flow rate
of the pump.
2. Inlet/outlet port diameters no smaller than the inlet port
diameter of the pump.
3. Degree of filtration:
Filter 1: 250 μ
Filter 2: 100 μ
Filter 3: 20 μ
For smooth pump operation, regular filter
cleaning is necessary, planned according to the
actual use of the pump in relation to the quality
of water used and actual clogging conditions.
In order to ensure the required supply pressure
(see par. 9.5) make provision for a pressure
switch.
2. The layout must be such as to prevent cavitation
problems.
3. Completely airtight and constructed to ensure a perfectly
hermetic seal through time.
4. Prevent the pump from emptying when it is stopped,
including partial emptying.
5. Do not use 3 or 4-way hydraulic fittings, adapters, swivel
joints, etc. as they could jeopardize pump performance.
6. Do not install Venturi tubes or injectors for detergent
suction.
7. Avoid use of foot valves or other types of unidirectional
valves.
8. Do not recirculate the by-pass valve drain directly to the
suction line.
9. Provide for proper guards inside the tank to prevent that
water flow from the bypass and the tank supply line can
create vortexes or turbulence near the pump supply pipe
port.
10. Make sure the suction line is thoroughly clean inside
before connecting it to the pump.
11. Install the pressure gauge for checking the booster
pressure near the plunger pump suction port and always
downstream from the filters.
1 Filter 1
2 Booster Pump
3 Filter 2
4 Filter 3
5 Pre-Filter Pressure Switch
Pressure Gauge
Bypass
26
6 Pre-Filter Pressure Switch
Pressure Switch
7 Pre-Filter Plunger pump
8 High pressure gauge
9 Safety valve
Fig. 7