Pratissoli SN64 Serie Manuel D'utilisation Et D'entretien page 32

9.4 Hydraulic connections
In order to isolate the system from vibrations produced by
the pump, it is advisable to make the first section of the duct
adjacent to the pump (both suction and outlet) with flexible
piping. The suction hose must be sufficiently rigid to prevent
deformation due to the negative pressure exerted by the
action of the pump.
9.5 Pump supply
A positive head of at least 0.20 meters is required for the best
volumetric efficiency with the fluid at ambient temperature
(see par. 9.6).
While with the fluid at high temperature max. 85°C, observe
the diagram below that defines the minimum supply
pressures according to the different temperatures.
Water temperature
For negative prevalence contact our Technical
Office or Customer Service Departments.
9.7 Filtration
1 filter must be installed on the pump suction line, positioned as indicated in Fig. 6 and Fig. 6/a.
With a manually activated control valve
Inlet
Supply tank
9.6 Suction line
For smooth operation of the pump, the suction line must have
the following characteristics:
1. Minimum inside diameter as indicated in the graph in par.
9.9 and in any case greater than or equal to the diameter
at the pump manifold.
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.
2. The layout must be made so as to ensure a minimum
positive head under all operating conditions of 0.20 m
(0.02 bar) and a maximum one of 80 m (8 bar) measured
on the pump supply; this minimum value applies for
cold water with temperature up to 20°C, for higher
temperatures refer to the specific graph (par. 9.5).
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.
Head
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.
1 Filter 1
2 Plunger pump
3 Pressure gauge
4 Safety valve
5 Manual control valve
Bypass
32
Fig. 6