Outlet Line; Calculation Of The Internal Diameter Of The Duct Pipes; Start-Up And Operation; Preliminary Checks - Pratissoli SK Série Manuel D'utilisation Et D'entretien

9.7

Outlet line

For the correct laying of the outlet line, the following
installation rules must be followed:
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 the vibrations
produced by the pump of 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.
5. Use pressure gauges suitable to withstand pulsating loads
typical of the plunger pumps.
6. During the design stage, keep in mind the line load losses
which result in a drop in pressure during use 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.
The graph does not take into account pipe
resistance, valves, load loss produced by the length
of the ducts, the viscosity of the liquid pumped or
the temperature itself.
If necessary, contact our Technical or Customer
Service Departments.
10

START-UP AND OPERATION

10.1

Preliminary checks

Before start-up, ensure that:
The suction line is connected and pressurised
(see chapter 9): the pump must never run dry.
1. The suction line ensures a hermetic seal over time.
2. Any shut-off valves between the supply source and
the pump are fully open. The outlet line during is free
discharge, to permit air present in the pump head to come
out quickly and therefore favour fast priming.
3. All suction and outlet fittings and connections are
properly tightened.
4. The coupling tolerances on the pump/transmission axis
(half-joint misalignment, Cardan joint tilt, etc.) remain
within limits required by the transmission manufacturer.
5. Oil in the pump casing is at the required level, verified with
the level indicators at the sides of the casing (pos. , Fig. 8).
In case of prolonged storage or long-term
inactivity, check proper functioning of the
suction and outlet valves.
10.2

Start-up

1. At first start-up, verify that the rotation direction and the
supply pressure are correct.
2. Start-up the pump without any load.
3. Check that the supply pressure is correct.
4. Check that the rotation rpm during operation does not
exceed the nominal rpm of the pump.
5. Let the pump run for a period of no less than 3 minutes,
before putting it under pressure.
6. Before each pump stop, reset pressure by means of the
control valve or with any relieving devices and reduce to a
minimum rpm (activation with combustion motors).
10.3

Seal packing cooling circuit

During operation, a certain amount of water coming from the
seal packing cooling circuit is discharged from the port 1 (Fig. 9).
The draining of this circuit must be sent back to the suction line
before the booster pump (Fig. 9), or to a tank for collection.
22
Fig. 8
Fig. 9