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 14
TM 9549
Edition 11/2017
1.4 Breakaway torques
Test medium: water 68 °F (20
C)
Higher breakaway torques may occur with other
media.
DN
p in psi
≤ 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“ 106 106 106
106
620
1½“ 177 177 177
221 1990
2“ 221 221 221
266 1990
3“ 531 531 575
708 4425
4“ 708 708 797
1505 4425
6“ 1770 2213 3098
-- 19470
8““ 1770 2213 3098
-- 19913
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
[%]
Characteristics
equal percentage
Rangeability 1:25
Best control range
20-90% of angle of
opening
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
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“/6“
186.4 291.25
466
8“
1165
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
