10
EB 8140 EN
Design and principle of operation
3 Design and principle of oper-
ation
The pneumatic control valve consists of a
globe (straight-pattern) valve with a soft-
seated plug and a pneumatic piston
actuator.
The medium flows through the valve in the
direction indicated by the arrow. The signal
pressure applied to the piston actuator deter-
mines the position of the plug and thus the
cross-sectional area of flow between the seat
and plug.
The plug/actuator stem (2) is sealed by a
self-adjusting PTFE V-ring packing (4.4) at
13
9
8
S
4.4
4.1
2
3
1
2
4.4
8
9
13
S
FE/NO
FA/NC
FE/NO
FA/NC
3
1
4.1
1
Body
2
Plug (with plug/actuator
stem)
4.1 Radial shaft seal
4.4 Packing rings
8
Piston
9
Spring
13 Vent plug
S
Signal pressure connection
Fig. 2:
Type 3354 Globe Valve · DN 15 to 50 (left) · DN 65 and 80 (right)
