Series MNKA,
acc. to ASME
Page 11
9250-050-en
Revision 11
TM 7903
Edition 07/2010
A distance depending on the coupling used is to be
observed between the pump and motor shafts.
See installation drawing.
Use supports in the direct vicinity of the bolts
foundation/base plate.
Ensure that the unit cannot be started during
work without the coupling guard.
5.4 Piping
Before the pump is installed, both the suction and
supply 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
before 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 diagrams or PC programs.
Fig. 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.
)
ft
(
A
x
449
)
gpm
(
Q
)
s
/
ft
(
v
2
=
)
m
(
A
)
s
/
m
(
Q
)
s
/
m
(
v
2
3
=
The velocity in the suction line should not exceed
6,56 ft/s (2 m/s) and 16,4 ft/s (5 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 shee
The NPSHR available in the plant
should be at least 1,64 ft (0,5 m)
higher than the NPSHR required for
the pump. Otherwise, this will lead to a drop in the
delivery head, cavitation or even failure of the pump.
5.4.2 Nozzle loads
The pump can be subjected to nozzle loads in
accordance with ANSI/HI 9.6..
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
gradient 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.
Fig. 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
upstream 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 escape 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.
