Design And Principle Of Operation - Samson 3349 Mounting And Operating Instructions

3 Design and principle of oper-
ation
The Type 3349 Angle Valve is preferably
combined with a SAMSON Type 3271 or
Type 3277 Pneumatic Actuator (see Fig. 3-1)
as well as the Type 3379 Pneumatic Piston
Actuator (see Fig. 3-2). The valve comes with
welding ends as standard. The valve is suit-
able for aseptic applications and is designed
without any cavities.
The process medium preferably flows
through the valve in the flow-to-open (FTO)
direction . The flow-to-close direction
1)
(FTC) is possible. The process medium al-
2)
ways flows through the micro-flow valve ver-
sion in the flow-to-close (FTC) direction. The
flow direction is indicated by an arrow on
the valve body. The position of the valve
plug determines the flow rate across the
cross-sectional area of flow released be-
tween the plug and lathed seat.
The plug stem is sealed by a full PTFE dia-
phragm that is USP Class VI certified. A
packing can additionally be used in the mi-
cro-flow valve version.
The test connection allows the diaphragm to
be monitored for leakage. In the version with
backup packing, the test connection is sealed
by a stopper. The stopper must be replaced
with a suitable leakage indicator (e.g. a con-
tact pressure gauge, an outlet to an open
vessel or an inspection glass) when the valve
is installed. The test connection of valves
FTO: Flow-to-open (flow under the plug)
1)
FTC: Flow-to-close (flow over the plug)
2)
EB 8048-2 EN

Design and principle of operation

without a backup packing is fitted with a
pipe elbow to allow the safe drainage of any
medium that escapes.
When combined with the Type 3271 or
Type 3277 Actuator, the actuator stem and
plug stem are connected using stem connec-
tor clamps (A26/27). When combined with
the Type 3379 Actuator, the actuator stem
and plug stem are screwed together.
Tip
We recommend the use of positioners with
integrated diagnostic firmware (see sec-
tion 3.4) for valves used for on/off service.
The partial stroke test included in this soft-
ware helps prevent a shut-off valve normally
in its end position from seizing up or getting
jammed.
3-1