Exhaust Back Pressure; Mechanical Installation; Priming And Recirculation Circuit; Electrical Installation - Grundfos Hydro EN Installation And Operating Instructions Manual

Section and path of the exhaust gas duct is vi-

tal to the proper functioning of the engine. The
design and execution must be properly carried
out by specialists commissioned by the client,
who will assume specific responsibility for the
work.
All the due precautions for making the dis-

charges free in air compliant with the regula-
tions in force at the place where the pumping
set is installed using filters, hoods, mufflers
and everything else adequate for the purpose
must be taken.
The exhaust gas duct and its insulation must

be suitably supported so the weight has not to
burden on the exhaust manifold of the engine.
The gas exhaust ducts must be arranged so as to allow the gas
to exit directly to the outside or through a pipe, depending on
the regulations in force at the place of installation.
In any case the exhaust must be protected from the weather
conditions.
The exhaust gas outlet must be positioned in order to ensure
that it does not cause disturbance to people or damage to
things.
The exhaust gas ducts must be made of steel, sufficiently
strong and perfect sealed.
Use of compensation joints to adequately meet the thermal
expansions of the exhaust gas ducts is always suggested.
Creation of a suitable condensation collection and drain point is
also required.
9.7

Exhaust back pressure

As previously stated, the exhaust gas must be conveyed
outside the installation room through pipes more or less long
according to the system.
This creates a back pressure in the engine exhaust duct that,
if too high a value, makes the outflow of the gases difficult and
reduces the efficiency of the motor.
After having used all the precautions for evacuating the exhaust
gas in an optimum manner, it is necessary to check the back
pressure value at the exhaust by measuring it in the following
work conditions:
• with the exhaust gas system in its final configuration,
• after a preliminary period of warming up the engine,
• at full load,
• at the nominal speed of the engine defined for the specific
model.
The value found must not be greater than the maximum value
recommended by each motor manufacturer and integral part of
the product documentation.
9.8

Mechanical installation

The diesel pump control panel has to be de-

tached from the motor frame and fixed to the
ground, this in order to avoid propagation of
vibrations to the electrical components.
A robust electrical earth connection between
the engine frame and the control panel stand
must be carried out with a cable of generous
section or metal braid.
The fuel tank can, if necessary, be removed

from the motor frame. In this case make sure
that the tank is positioned on the same founda-
tion of the engine, or at least the same height,
to ensure that the fuel feeds the injection pump
by gravity.
A robust electrical earth connection between
the engine frame and the control panel stand
must be carried out with a cable of generous
section or metal braid.
If the sets are supplied in macro components, it is necessary to
reassemble the structure of the set before performing any other
operation.
The pumping set must be placed on a flat and smooth surface,
for example, a floor or concrete foundation.
The pipes connected to the pumping set must be of adequate
size and especially the suction pipes must be such as to
observe the criteria prescribed by the norm EN 12845 regarding
the water speed in the pipes (1,8 m/s for positive head installa-
tions and 1,5 m/s for those in suction lift).
Special attention must also be paid to choosing components
and the suction path route, which must be executed in order to
ensure that the NPSH available at the pump suction port is at
least 1 m greater than the NPSH required by, with the maximum
flow rate required.
Always prevent the suction pipe from having reverse gradients
such as to create a drain trap effect.
To prevent resonances or mechanical tensions due to incorrect
alignment, expansion joins must be installed on the discharge
manifold (and on the suction manifold, if present).
Installation of pipe supports is always required, following the
instructions provided by the EN 12845 on pumping set dis-
charge and suction side so as to not have the weight of the
pipes rest on the manifold (including the suction manifold, if
present) or on the pumps.
9.9

Priming and recirculation circuit

In accordance with the requirements of the EN 12845 standard,
the pumps are equipped with connections for both the priming
and recirculation circuits.
The connection should be made taking into account the follow-
ing:
• use the 2" connection on the pumping set to connect the
priming circuit (hydraulic components not included in the
scope of supply of the pumping set),
• in case of electrically driven pumps or diesel driven pump
with direct air cooling system use the 1" plug available on
the discharge to connect the circulation circuit to the suction
storage tank,
• in case diesel driven pumps with water/water heat exchanger
cooling system the circulation is performed through the cool-
ing system (see dedicated paragraph),
• connect the priming tank to the suction tank through an over-
flow drain.
Use the functional diagram as reference.

9.10 Electrical installation

The terminals and wires upstream of the panel

mains switch are supplied even if the switch is
in the OFF position.
Cut off the voltage by using the mains general
switch and block it in the OFF position to en-
sure that it cannot accidentally reactivate.
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