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3.17.6 Suction and discharge pipes
3.17.6.1 Forces and moments
Note! Excessive forces and moments on the nozzle flanges derived from piping can cause
mechanical damage to pump or pump unit.
Pipes should therefore be connected in line, limiting the forces on the pump connections.
Support the pipes and make sure they remain stress-free during operation of the pump.
z F
See table for maximum allowable forces (F
on a solid foundation (e.g. grouted base plate or solid frame).
When pumping hot liquids attention should be given to forces and moments caused by thermal
expansion in which case expansion joints should be installed.
Check after connecting whether the shaft can move freely.
3.17.6.2 Piping
•
Use piping with an equal diameter than the connection ports of the pump and shortest possible.
•
The pipe diameter has to be calculated in function of the liquid parameters and the installation
parameters. If necessary use larger diameters to limit pressure losses.
•
If the fluid to be pumped is viscous, pressure losses in the suction and discharge lines may
increase considerably. Other piping components like valves, elbows, strainers, filters and foot
valve also cause pressure losses.
•
Diameters, length of piping and other components should be selected in such a way that the
pump will operate without causing mechanical damage to the pump/pump unit, taking into
account the minimum required inlet pressure, the maximum allowable working pressure and the
installed motor power and torque.
•
Check the tightness of the pipes after connection.
Suction piping
•
Liquids should preferably enter the pump from a level higher than the pump level. In case the
liquid should be sucked from a level lower than the pump level, the inclining suction pipe should
rise upwards towards the pump without any air pockets.
•
A too small diameter or a too long suction pipe, a too small or blocked strainer will increase
pressure losses so that the NPSHa (NPSH available) becomes smaller than the NPSH
(NPSH required).
Cavitation will occur, causing noise and vibrations. Mechanical damage to pump and pump unit
is not excluded.
•
When a suction strainer or filter is installed pressure losses in the suction line must be checked
constantly. Also check if the inlet pressure at the suction flange of the pump is still sufficiently
high.
•
When the pump works in both directions, pressure losses must be calculated for both directions.
30
F
y
M
y
M z
x, y, z
TG BLOC pump size
15-50
23-65
58-80
86-100
M
x
F x
) and moments (M
) on the nozzle flanges with pump
x, y, z
A.0500.751 – IM-TGBLOC/01.00 EN (10/2020)
F
(N)
M
(Nm)
x, y, z
x, y, z
2600
675
2900
800
3550
1375
4100
1750
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