Good
No good
Good
Good conditions
Unacceptable conditions
No good
Good
No good
Good
No good
Air trap
Air trap
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M
Suction piping
[1]
The suction pipe should employ the flooded suction method if possible. The shortest pipe possible, with the
minimum number of bends, should be used. Arrange a proper support under the suction pipe such as an
expansion joint or the like so that the weight and thermal stress of the pipe are not applied to the pump.
[2]
Attach the coupling on the suction pipe carefully so as not to allow air inside the line. Air in the suction pipe
may damage the system.
[3]
If suction is not good (e.g., the suction tank is a vacuum, the suction head is large, or the suction pipe is long),
the condition NPSHa > NPSHr + 0.5 m should be established. For the NPSHr level, refer to the standard
performance curve.
[4]
When using an elbow pipe on the suction side, install a straight pipe with a length of at least 500 mm or 8 times
the suction port diameter before the pump suction port. Provide the largest radius possible for the R of the bend.
[5]
Do not allow any projection where air may be trapped along the suction pipe. The suction pipe should have an
ascending gradient of 1/100 toward the pump.
Air trap
Air trap
