Figure 32: Neither Recommended
Min O
C
= 45°
Preferred O
C
= 75°
Figure 33: Recommended
Figure 34: Not Recommended
The velocity of the water approaching the pump suction pipe should be kept to a maximum of one foot
per second to avoid air being drawn into the pump. Pump suction inlet velocities and submergence (the
height of the water above the pump inlet) are two additional factors that must be considered. These fac-
tors vary so greatly with the size and capacities of the individual pumps and systems that past experi-
ence, or a good reference, should be relied upon in arriving at these values.
The suction pipe should be sized to obtain a flow velocity of 4 to 7 feet per second. Changes in flow di-
rection should be avoided wherever possible, especially near the pump suction. A reducer at the pump
suction flange to smoothly accelerate and stabilize flow into the pump is desirable.
Refer to the nearest Goulds representative for further information.
4.8.1 Installations with Pump Above Source of Supply - Suction Lift
1.
Keep suction pipe free from air pockets - See
Figure 26: Incorrect Piping on page 26
2.
Piping should slope upwards from source of supply.
3.
No portion of piping should extend above the pump suction nozzle.
4.
All joints must be air tight.
4.8.2 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 of the line for pump inspection
and maintenance.
4.8 Suction Piping Design for Large Pumps
28
3175 Installation, Operation and Maintenance Instructions
