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Pump Minimum Speed and Impeller Dia

Pump Minimum Speed and Impeller Dia

Pump Minimum Speed and Impeller Dia

(OP)
Hi,
Can any one expalin indetail from where these values are taken for the calculation of pump minimum specific speed and impeller dia.
1-N=LogQ/2.3026-0.75/.0025
2-D=1840*1.15*SQRT of Head/N
Where,
in equation one, i can't understand about 2.3026 and 0.0025 and in equation 2, 1840, 1.15?
Thanks
MIANCH

RE: Pump Minimum Speed and Impeller Dia

It might help if you told us where these formula came from.

RE: Pump Minimum Speed and Impeller Dia

(OP)
These are from worleyparsons design data file.

RE: Pump Minimum Speed and Impeller Dia

I had to dig into the old memory bank to come up with the relevant formulae.

1.  V = sq rt (2gh) ft/sec  ( peripheral speed)
 where g = 32.2 ft/sec squared
       h = head in feet

2.  V=  3.14d * N/(12*60)
      where d= dia in inches
            N= RPM
      DIVIDE BY 12 FOR FEET
      DIVIDE BY 60 FOR FT/SEC

combine & solve both formulae for d.

Worley parsons 1.15 constant is an unknown source, probably an allowance factor.

The specific speed formulae i have no knowledge of its source at present.

Offshore Engineering&Design

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