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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
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