2.5 Piping - suction
1.
Properly installed suction piping is of extreme importance for trouble-free centrifugal pump opera-
tion.
1.
The suction pipe should be as large or larger than the pump suction.
2.
Increasers, if used, should be eccentric and preferably at or near the pump suction
flange.
3.
A centrifugal pump should never be throttled for capacity adjustment on the suction side.
Installation with pump above source of supply - suction lift:
1.
Keep suction pipe free from air pockets.
1.
Piping should slope upwards from source of supply.
2.
No portion of piping should extend above the pump suction nozzle.
2.
All joints must be air tight.
3.
The suction pipe should always be submerged into the source of supply as shown in Figure 2.
4.
A foot valve should only be used if necessary for priming, or, if the pump is to be used on inter-
mittent service and is required to hold its prime.
5.
Suction strainers when used should have a net free area of at least three times the suction pipe
area.
Installations with pump below source of supply - suction head or flooded suction:
1.
A gate valve should be installed in the suction line to permit closing the line for pump inspection
and maintenance.
2.
The size of the entrance from the source of supply or minimum submergence over the entrance
should be calculated from the data as shown in Figure 2 for applicable condition to prevent air
from being drawn into the pump.
2.6 Piping - discharge
1.
A gate valve and a check valve should be installed in the discharge line. The check valve should
be located between the gate valve and pump to permit inspection of the check valve. The gate
valve is required for priming, regulation of flow capacity and for inspection and maintenance of
the pump.
2.
Increasers, if used in discharge line, should be placed between the check valve and the pump.
2.7 Connection of piping
Connect suction and discharge piping. Rotate the pump shaft by hand several complete revolutions to be
sure that there is no binding and that all parts are free.
If the connection of the piping causes unit to rub, correct piping to relieve strain on the pump.
2.8 Check rotation
These pumps are built in right hand construction, i.e., clockwise rotation when viewed from driver end.
The direction of rotation is marked on the pump casing. Make sure that driver rotates in the same direc-
tion.
2.5 Piping - suction
14
3655 Installation, Operation and Maintenance Instructions
