Samson 3244, Монтаж и эксплуатация, Страница: 15 / 72

EB 8026 EN 3-1
Design and principle of operation
3 Design and principle of oper -
ation
See Fig. 3-1 and Fig. 3-2 on page 3-2.
The Type 3244 is a three-way valve which
can be used either as a mixing or diverting
valve. The design of the mixing and diverting
valves in sizes DN 15 to 25 (NPS ½ to 1) is
identical. The Type 3244 Valve is preferably
combined with a SAMSON Type 3271 or
Type 3277 Pneumatic Actuator. It can also
be combined with other actuators.
The two seats (4 and 141) and plug with
plug stem (5) are installed in the body (1).
The plug stem is connected to the actuator
stem (A7) by the stem connector clamps
(A26/27) and is sealed by a spring-loaded
V-ring packing (15). The springs in the
pneumatic actuator (A) are located either
above or below the diaphragm depending
on the selected fail-safe action. A change in
the signal pressure acting on the diaphragm
causes the plug to move. The actuator size is
determined by the diaphragm area.
The medium flows through the valve in the
direction indicated by the arrow. A rise in
signal pressure causes the force acting on
the diaphragm in the actuator to increase.
The springs are compressed. Depending on
the selected direction of action, the actuator
stem retracts or extends. As a result, the plug
position in the seats changes and determines
the flow rate through the valve.
In mixing valves, the process media to be
mixed enter at valve ports
A and B . The
combined flow exits the valve at port AB (see
Fig. 3-1).
In diverting valves, the process medium en-
ters at the valve port
AB and the partial
flows exit at ports A and B (see Fig. 3-2).
Fail-safe action
The fail-safe position of the control valve up-
on air supply or control signal failure de-
pends on the actuator used (see associated
actuator documentation).
Depending on how the compression springs
are arranged in the SAMSON Type 3271
and Type 3277 Pneumatic Actuator, the
valve has one of two different fail-safe posi-
tions:
Legend for Fig. 3-1 and Fig. 3-2
1 Body
2 Flange
4 Top seat
5 Plug (with plug stem)
8 Threaded bushing
(packing nut)
9 Stem connector nut
10 Lock nut
14 Nuts
15 Packing
17 Body gasket
84 Travel indicator scale
141 Bottom seat
A7 Actuator stem
A8 Ring nut
A26/
27 Stem connector clamps