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Caution
Caution
Multitec
9
5.4 Connecting the piping
Suction lift lines shall be laid with a rising slope towards the
pump and suction head lines with a downward slope towards
the pump, to prevent the formation of air pockets.
With short pipelines, the nominal diameters should be at least
equal to the nominal diameters of the pump nozzles. For long
pipelines, the most economical nominal diameter has to be
determined from case to case.
Adapters to larger diameters should have a diffuser angle of
approx. 8° in order to avoid any pressure losses caused by the
formation of air pockets or gas.
It is recommended to install check and shut-off elements in the
system, depending on the type of plant and pump.
Never use the pump itself as an anchorage point
for the piping. The piping-induced forces and
moments acting on the pump flanges (e.g. due to warped
pipelines or thermal expansion) must not exceed the
permissible forces and moments.
The pipelines shall be anchored in close proximity to the pump
and connected without transmitting any stresses or strains.
Their weight must not be carried by the pump.
If welding work must be performed on the piping
when the pump is already installed, the electric
welding equipment must not be earthed on the pump or
baseplate, to prevent current flowing through the rolling element
bearings, which could cause their premature destruction (pitting
effect).
Thermal expansions of the pipelines must be
compensated by appropriate measures so as not to
impose any extra loads on the pump.
Expansion joints may have to be used. An excessive,
impermissible increase in the pipeline forces may cause leaks
on the pump where the fluid handled can escape into the
atmosphere.
Danger to life when hot fluids are handled!
Fig. 9 Max. nozzle forces and moments
Direction of forces:
X = horizontal, parallel to the pump axis
Y = vertical to the pump axis
X = horizontal, at a right angle to the pump axis
Direction of moments:
X = around the horizontal axis, parallel to the pump axis
MY = around the vertical nozzle axis
X = around the horizontal axis, at a right angle to the
pump axis
Suction and discharge nozzle are regarded separately.
Max. permissible pipeline forces
(material codes 10, 11, 12, 13)
Nom. nozzle diameter (DN)
32 50 65 80 100 125 150 200 250
Vertical nozzle, at a right angle to the shaft (N )
Fx 245 510 640 700 1015 1470 1780 2700 -
Fy 410 635 800 970 1270 1850 2220 3490 -
Fz 265 415 520 625 830 1220 1465 2220 -
Horizontal nozzle, at a right angle to the shaft (N )
Fx 245 510 640 800 1015 1470 1780 2700 -
Fy 265 415 520 625 830 1220 1465 2220 -
Fz 410 635 800 970 1270 1850 2220 3490 -
Axial nozzle, parallel to the shaft (N )
Fx - - 800 - 1270 1850 2220 3490 4760
Fy - - 520 - 830 1220 1465 2220 3180
Fz - - 640 - 1015 1470 1780 2700 3810
Moments for all nozzles (Nm )
Mx 260 330 460 680 950 1235 1640 2520 3580
My 160 250 350 520 715 930 1260 1840 2710
Mz 190 170 240 340 490 660 840 1260 1740
Example:
Multitec 50 with radial suction nozzle
- forthesuctionnozzle,the valuesgiven intablecolumnDN80
apply
- for the discharge nozzle, the values given in table column
DN50 apply
Max. permissible pipeline forces
(material codes 20 to 30)
The values given for material codes 10, 11, 12,13 shall be
multiplied by the factor 1.4.
Protection against foreign matter
Before commissioning new installationsthoroughly clean,flush
and blow through all vessels, pipelines and connections.Often
welding beads, scale and other impurities only come off after a
certain period of operation. Fit a strainer in the suction line to
preventthem fromentering the pump.The total cross-section of
the holes in the strainershall be three timesthe cross-sectionof
the pipeline in order to avoid excessive pressure loss across
the strainer due to clogging. Conical strainers with laid in wire
mesh having a mesh width of 0.5 mm and a wire diameter of
0.25 mm, of corrosion-resistant material, shall be used.
1 Strainer housing
2 Fine screen
3 Perforated plate
4 Pump suction nozzle
5 Differential pressure gauge
Fig. 10 Conical strainer for the suction line