Civil Engineering Reference
In-Depth Information
Fig. 26-19.
Combining flow—branch angle 60
—loss coefficient
K
13
(
Source:
Reference 7; cour-
tesy of the BHR Group Limited)
Cavitation of Ball Valves
The critical cavitation velocities,
U
cr
, for ball valves are
shown in Figure 26-33 (page 929). The velocities are corrected to other head condi-
tions by using:
0.4
h
h
u
v
U
U
(26-19)
c
cr
50
Cavitation of Orifices
The mean velocities associated with incipient, critical,
incipient damage, and choking cavitation are shown in Figure 26-34 (page 929).
7
The
base conditions are a pipe diameter,
D
, of 0.076 m, an upstream head of 63 m gage
and a vapor head,
h
v
,of
8.6 m gage.
To correct the velocities to other conditions, use the following equation:
0.5
h
u
v
U
or
U
CU
(26-20)
i
c
1
r
71.6
where
C
1
is taken from Figure 26-35 (page 930).
