Filtration; Outlet Line; Calculation Of The Internal Diameter Of The Duct Pipes - Pratissoli SKH Serie Manual De Uso

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 baffles inside the tank to prevent the
water flow from the bypass and the tank supply line from
creating vortexes or turbulence near the pump feeding
pipe port.
9.6

Filtration

The permissible filtration for this series of pumps must be max. 20 μm (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 No. 1: 250 μm
- Filter No. 2: 100 μm
- Filter No. 3: 20 μm
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. 9.4) make provision for a pressure
switch.
9.7

Outlet line

For correct design of the outlet line comply with the following
installation prescriptions:
1. The internal diameter of the pipe must be sufficient to
ensure correct fluid velocity, see graph in par. 9.8.
2. The first section of the line connected to the pump outlet
must be a flexible hose, in order to isolate vibration
produced by the pump from the rest of the system.
3. Use high pressure pipes and fittings to ensure high safety
margins in all operating conditions.
4. The outlet line must always be provided with a Max.
pressure valve.
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 Pressure gauge
Bypass
5. Use pressure gauges capable of withstanding the
pulsating loads typical of plunger pumps.
6. During the design stage, keep in mind the line pressure
drops that lead to a pressure reduction at the user with
respect to the pressure measured on the pump.
7. For those applications where pulses produced by the
pump on the outlet line may prove harmful or unwanted,
install a pulsation dampener of sufficient size.
9.8 Calculation of the internal diameter of the
duct pipes
To determine the internal diameter of the duct, refer to the
following diagram:
Suction duct
With a flow rate of ~ 99 l/min and a water velocity of 0.5 m/sec.
The graph line joining the two scales meets the central scale,
showing the diameters, corresponding to a value of ~ 65 mm.
Outlet duct
With a flow rate of ~ 99 l/min and a water velocity of 5.5 m/sec.
The graph line joining the two scales meets the central scale,
showing the diameters, corresponding to a value of ~ 19 mm.
Optimal speeds:
- Suction: ≤ 0.5 m/sec.
- Outlet: ≤ 5.5 m/sec.
22
6 Pressure switch
7 Plunger pump
8 High pressure
gauge
9 Safety valve
Fig. 7