Richter MNK Series, Инструкция по установке и эксплуатации

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Series MNK pedestal group 4
Page
11
9230-003-en Revision 19
TM 10458 Edition 06/2022
5.4 Piping
Before the pump is installed, both, the suction and sup-
ply lines as well as the discharge line are to be cleaned.
Dirt or damage to the sealing surfaces is best avoided
if the flange covers remain on the flanges until just be-
fore installation.
Use flange gaskets suitable for the medium.
The screw tightening torques in Section 1.1 are to be
observed for tightening the flange screws.
5.4.1 Nominal size
The operating design point of a centrifugal pump lies at
the intersection of the pump curve and the pipe curve,
see
Fig. 2 . The pump curve is provided by the pump
manufacturer. The pipe curve is determined using dia-
grams or PC programs.
picture 2
Under no circumstances can the nominal size of the
piping be derived from the connected nominal size of
the pump.
The pipe nominal size can also be determined using
the flow rate as a rough guide.
The velocity in the suction line should not exceed 2.0
m/s and 5.0 m/s in the discharge line.
When determining the suction line nominal size, the
NPSH value (net positive suction head) must also be
observed. The NPSHR value required for the pump is
specified in the data sheet.
The NPSHR available in the plant
should be at least 0.5 m higher
than the NPSHR required for the
pump. Otherwise, this will lead to a
drop in the delivery head, cavita-
tion or even failure of the pump.
5.4.2 Nozzle loads
The pump can be subjected to nozzle loads acc. to DIN
EN ISO 5199. Values see installation drawing.
Changes in the length of the piping caused by
temperature are to be allowed for by appropriate
measures, e.g. the installation of expansion joints.
5.4.3 Suction line
The suction lines must always be laid on a rising gradi-
ent towards the pump. Otherwise, gas bubbles may
form which considerably reduce the suction line cross
section. Eccentric transition elements must be installed
between different pipe diameters.
Valves which disrupt the course of flow should not be
installed directly upstream of the pump.
picture 3
5.4.4 Supply lines
Supply lines should vent towards the reservoir and are
therefore to be laid with a constant downward gradient
towards the pump. Should the piping internals up-
stream of the pump be horizontal, a low point can, of
course, be located upstream of these internals. From
here the pipe is then laid with an upward gradient to the
pump so that the gas bubbles which form here can es-
cape through the pump.
Valves which disrupt the course of flow should not be
installed directly upstream of the pump.
5.4.5 Discharge line
Do not arrange the shut-off valve directly above the
pump but initially provide a transition section.
The discharge nozzle velocity of the medium can
–
if
necessary
–
be reduced.
) m ( A
) s / m ( Q
) s / m ( v
2
3
=