Samson 3724, Монтаж и эксплуатация

Страница: 17 / 40

EB 8395 EN 17
Mounting and start-up
FA: actuator stem extends (air to open/
ATO)
Fail-close (for globe and angle valves):
Required supply pressure = Upper bench
range value + 0.4 bar, minimum 1.4 bar.
FE: actuator stem retracts (Air to close/ATC)
Fail-open (for globe and angle valves):
For tight-closing valves, the maximum signal
pressure pst
max
is roughly estimated as fol-
lows:
pst
max
= F +
d² · π · ∆p
[bar]
4 · A
d = Seat diameter [cm]
∆p = Differential pressure across the
valve [bar]
A = Actuator area [cm²]
F = Upper bench range value [bar]
If there are no specifications, calculate as
follows:
Recommended supply pressure =
Upper bench range value + 1 bar
The signal pressure at the output (38) of the
positioner can be restricted to approx.
2.3 bar by setting P9 parameter code to
ON.
Note