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The version can only be modified by trained and
authorized personnel and carefully following the
instructions below:
1. Separate the hydraulic part from the mechanical
part as indicated in the repair manual.
2. Turn the mechanical part 180° and reposition
the rear casing cover in such a way that the oil
dipstick is turned upward. Reposition the lifting
bracket and the plugs with their ventilation hole
closing caps in the upper part of the casing.
Finally, properly reposition the specification
label in its housing on the casing.
Make sure that the lower casing draining
holes in correspondence with the pistons
are open and not closed by the plastic caps
provided for the previous version.
3. Unite the hydraulic part to the mechanical part
as indicated in the repair manual.
In addition it is possible to position the reduction unit in 4
different positions as per Fig. 7.
The position of the reduction unit can only be
changed by authorized specialized personnel
meticulously following the instructions in the
repair manual.
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
VKH 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.
In order to ensure the seal durability it is
recommended, if necessary, to operate the pump
at a minimum pressure of 25-30 bar.
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.
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
Fig. 7
downstream from the filters.
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