Samson 3246, Mounting And Operating Instructions

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EB 8046 EN 3-1
Design and principle of operation
3 Design and principle of oper -
ation
The Type 3246 is available in three different
versions:
− Globe valve, Class 150 and 300/PN 16
and 40 (see Fig. 3-1)
− Globe valve, Class 600 and 900/
PN 100 and 160 (see Fig. 3-3)
− Three-way valve, Class 150 and 300/
PN 16 and 40 (see Fig. 3-2)
The Type 3246 Valve is preferably combined
with a SAMSON Type 3271 or Type 3277
Pneumatic Actuator. It can also be combined
with other actuators.
The springs in the pneumatic actuator are lo-
cated either above or below the diaphragm
depending on the selected fail-safe action
(see section 3.1). A change in the signal
pressure acting on the diaphragm causes the
plug to move. The actuator size is deter-
mined by the diaphragm area.
Globe valves
The seat (4) and plug (5) are installed in the
body (1). For low pressure ratings
(Class 150 and 300/PN 16 and 40), the
plug is screwed to a plug stem extension
(25). For Class 600/PN 100 and higher, the
plug and plug stem are incorporated in one
piece. The stem connector clamps connect
the actuator stem of the mounted actuator.
The plug stem or plug stem extension is
sealed by a spring-loaded V-ring packing
(15).
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 seat changes and determines
the flow rate through the valve.
Three-way valve
Two seats (4, 141) are installed in the body
(1) of the three-way valve. Depending on the
version, the three-way valve can be used ei-
ther as a mixing or diverting 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.
The flow rate from ports A or B to AB de-
pends on the cross-sectional area of flow be-
tween the seats and plugs. Fig. 3-2 shows a
mixing valve.
In diverting valves, the process medium en-
ters at the valve port AB and the partial
flows exit at ports A and B.
The design of the mixing and diverting
valves in sizes NPS ½ to 1 (DN 15 to 25) is
identical.
Insulating section and circulation inhibitor
To withstand low temperatures, the
Type 3246 Valve is always fitted with a long
insulating section (21). A circulation inhibitor
(86) is installed in the lower section of the in-
sulating section of all three versions. This
prevents the cold process medium from circu-
lating in the insulating section.
Note