Interpump Group 70 HT Serie Manual De Uso Y Mantenimiento página 24

9.6 Suction line
For a smooth operation of the pump, the suction line should
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.
Localised restrictions should be avoided
along the run of the duct, as these can cause
load losses resulting in cavitation. Avoid 90°
elbow bends, connections with other piping,
constrictions, counterslopes, inverted U- curves and
T-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 (chapter 7,
Operating Instructions).
The pumps can also operate with a lower supply pressure,
under certain operating conditions expressly authorized
by our Technical or Customer Service Departments.
3. Completely airtight and constructed to ensure sealing
over time.
9.7 Filtration
On the pump suction line it is necessary to install a filter, located as near as possible to the pump (diagrams Fig. 6 and Fig. 6/a)
and easy to inspect, with the following features:
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. Filtration grade between 200 and 360 µm.
With a manually activated control valve
Inlet
Supply tank
4. Prevent that pump stopping causes emptying, even
partial.
5. Do not use 3 or 4-way hydraulic fittings, adapters, swivel
joints, etc. as they could jeopardise pump performance.
6. Do not install Venturi tubes or injectors for detergent
suction.
7. Avoid use of base valves or other types of unidirectional
valves.
8. Do not recirculate by-pass valve discharge directly into
suction.
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 Booster pump
2 Filter
3 HT series pump
4 Pressure gauge
5 Safety valve
6 Manual control valve
Bypass
24
Fig. 6