Instruction Manual

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
m
edia.
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 : n
on-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“ 0.931.86 4.66 9.32 16.3 23.3
¾“ 0.931.86 4.66 9.32 16.3 23.3
1“ 0.931.86 4.66 9.32 16.3 23.3
1½“ 18.6429.12 46.6
2“ 18.6429.12 46.6 69.9
3“ 46.6 93.2 139.8 186.4
4“ 69.9 116.5186.4 291.25
6“ 186.4291.25 466
8“ 186.4291.25 466
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
pp
v
=


1