Pump Minimum Speed and Impeller Dia

[MIANCH]

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

 

[Artisi]

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

 

[MIANCH]

These are from worleyparsons design data file.

 

[chief]

http://www.ramueller.com/handbook/centrifuge.html

ALL YOU NEED TO KNOW

Offshore Engineering&Design

 

[chief]

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