16
Competence in Functional Safety
Functional safety of globe valves, rotary plug valves, ball valves and butterfly valves
5.4 Butterfly valve requirements
Responsibility
On sizing actuators for butterfly valves, note that the actuator must provide suf-
ficient torque to overcome the breakaway torque and closing torque in closed
position as well as the dynamic torque in open position.
On mounting the actuator on the butterfly valve, the breakaway torque of the but-
terfly valve in relation to the differential pressure and the permissible torque of the
butterfly valve shaft must be observed.
Manufacturer
Nominal size Perm. torque
M
dmax
(Nm)
Perm. torque M
dl
in Nm at a differential pressure
∆
p (bar)
DN
NPS
0 bar
5 bar
10 bar
16 bar
80
3
280
40
43
45
51
100
4
280
48
54
59
67
150
6
505
91
106
114
157
200
8
785
190
219
269
288
250
10
785
320
364
433
480
300
12
1591
370
467
578
654
400
16
3215
690
903
1089
1239
Example: Required manufacturer specifications
Note that high dynamic torques can arise at high differential pressures in the process
medium, pushing open the butterfly disc.
Operator
Dynamic torque of butterfly valves in relation to the opening angle
