Samson 3244 - Design and Principle of Operation

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 divert-
ing valves in sizes DN15 to 25 (NPS½ to
1) is identical. The Type3244 Valve is pref-
erably combined with a SAMSON
Type3271 or Type3277 Pneumatic Actua-
tor. It can also be combined with other actu-
ators.
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 pneu-
matic actuator (A) are located either above
or below the diaphragm depending on the
selected fail-safe action. A change in the sig-
nal pressure acting on the diaphragm causes
the plug to move. The actuator size is deter-
mined by the diaphragm area.
The medium ows 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 ow rate through the valve.
In mixing valves, the process media to be
mixed enter at valve ports A and B. The
combined ow 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
ows 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