4 breakaway torques, 6 flow values kv in, 7 flow values kv100 in m3/h – Richter KNARP-S/F Series Control Ball Valves User Manual
Page 5: Breakaway torques, Cv/cv, Flow values kv in, Flow values kv100 in m, Series series knar/f, knarp/f, knar-d/f, knarp-d/f, Knar-s/f, knarp-s/f, 5 cavitation coefficient z for 75% duty (cv/cv
Series Series KNAR/F, KNARP/F, KNAR-D/F, KNARP-D/F,
Page 5
KNAR-S/F, KNARP-S/F
ASME
9520-082-en
Revision 04
TM 7377
Edition 11/2008
1.4 Breakaway torques
Test medium: water 68 °F (20
°C)
Higher breakaway torques may occur with other
media.
DN
p in psi
F 45
85
145
235
max.
adm.
[inch] [in-lbs] [in-lbs] [in-lbs]
[in-lbs]
[in-lbs]
½“
71
71
71
89
620
¾“
71
71
71
89
620
1“
106
71
71
89
620
1½“ 177
177
177
221
1990
2“
221
221
221
266
1990
3“
443
443
549
708
4425
4“
708
708
814
974
4425
6“
1770
2036
2390
2744
19470
8““
1770
2036
2390
2744
19915
The breakaway torque of the actuator must be at least
just as high as the breakaway torque of the valve but
better would be 20% higher.
With highly viscous media and/or solids in the medium
it may be necessary to consider other safety
allowances in dimensioning the actuator.
This applies in particular to non-Newtonian fluids, such
as high polymer substances, suspensions, pastes,
lubricants, resins, paints etc.
Admissible safety allowances are in the range of 20-
25% of the breakaway torque.
In order to avoid damage to the valve, it is imperative
to observe the max. admissible breakaway torque!
1.5 Cavitation coefficient z for
75% duty (Cv/Cv
100
=0,75)
There are at least 3 different V-control ball/stem units
for each nominal size
DN
z1
z2
z3
z4
z5
z6
½“
0,65
0,60
0,60
0,60
0,58
0,43
¾“
0,65
0,60
0,60
0,60
0,58
0,43
1“
0,65
0,60
0,60
0,60
0,58
0,43
1½“
0,53
0,50
0,35
2“
0,47
0,39
0,32
3“
0,31
0,29
0,22
4“
0,27
0,24
0,16
6“
0,15
0,13
0,08
8“
0,15
0,13
0,08
X
F
z
:
non-critical conditions
X
F
1,4
x
z
:
tolerable cavitation
X
F
> 1,4
x
z
:
inadmissible cavitation
1.6 Flow values Kv in %
Opening
[%]
Kv
[%]
10
5,5
20
7,6
30
10,5
40
14,5
50
20,0
60
27,6
70
38,1
80
52,5
90
72,5
100
100,0
Characteristics
equal percentage
Rangeability 1:25
Best control range
20-90% of angle of
opening
1.7 Flow values Kv100 in m
3
/h
There are 3-6 different V-control ball/stem units per
nominal size
DN
Cv
[inch]
[USgpm]
½“
0.93 1.86
4.66
9.32
16.3
23.3
¾“
0.93 1.86
4.66
9.32
16.3
23.3
1“
0.93 1.86
4.66
9.32
16.3
23.3
1½“
18.64
29.12
46.6
2“
18.64 29.12
46.6
69.9
3“
46.6
93.2
139.8
186.4
4“
69.9 116.5
186.4
291.25
6“
186.4
291.25
466
8“
186.4
291.25
466
X
F
= Differential pressure ratio
p
= Differential pressure input/outlet
p
1
= Absolute pressure at inlet
p
v
= Vapour pressure at operating temp.
X
F
p
p p
v
=
1