Samson 3271-5, Монтаж и эксплуатация

Страница: 12 / 52

12 EB 8310-1 EN
Design and principle of operation
3 Design and principle of oper-
ation
The Type 3271-5 and Type 3277-5 Actua
-
tors have an actuator area of 120 cm². The
actuators mainly consist of two diaphragm
cases (A1, A2), a rolling diaphragm (A4),
and internal springs (A10). See Fig. 2 and
Fig. 3. The actuators are mounted in particu
-
lar on SAMSON Series 240 Valves and
Type 3510 Micro-flow Valves.
The signal pressure p
st
creates the force F =
p
st
· A at the diaphragm surface A which is
opposed by the springs (A10) in the actua-
tor. The bench range is determined by the
number of springs used, taking into account
the rated travel. The travel is proportional to
the signal pressure p
st
. The direction of ac-
tion of the actuator stem (A7) depends on
how the springs are installed in the actuator.
A maximum of twelve springs, partly fitted in
one another, can be installed in the actuator.
The stem connector clamps (A26/27) of
Series 240 Valves connect the actuator stem
(A7) with the plug stem of the valve. The
actuator stem (A7) and plug stem (5) of the
micro-flow valve are connected using a
threaded stem connection.
The Type 3277-5 Actuator is fitted with an
additional yoke on the bottom diaphragm
case (see Fig. 3). It allows the direct attach
-
ment of a positioner and/or limit switch. The
benefit of this design is that the travel pick-
off located inside the yoke is protected
against external influences.
A4
S
A5.1
A5.2
A26/27
A8
A41
A42
A40
A16
A1
A7
A15 A9 A10 A20/21
A2 A46
Fig. 2: Type 3271-5 Actuator with
120 cm² actuator area