loss coeffiecients in ball valves 2

[talpacino]

hi, im looking for some help on what the typical loss coefficients for a fully open 3" ball valve might be and the response type, eg; equal percentage, linear, etc.

i cant seem to find any useful data anywhere on this, any ideas?

 

[Leclerc]

The loss coefficient for a fully opened ball valve with the opening the same area as the pipe is essentially only the friction loss of an equivalent length of pipe, typically o.o5. for reduced bore valves, when fully open, the loss coeffiecient is that of a long orifice. Atypical value is 0.5 for a valve with an opening 70% of the pipe area.

For varaition in loss coefficient with valve position:


Valve Angle (deg.)
Ball/pipe area Ball/pipe area
1.0 0.7
Loss coeff.,K
0.1 90
0.5 80 90
1.0 74 85
5 55 73
10 45 68
50 27 51
100 20 44
400 10 30

points taken from Ref. Miller D.S. (1990) "Internal Flow Systems" 2nd Ed. BHRA (Information Services)