Design And Principle Of Operation - Samson 3275 Mounting And Operating Instructions

Design and principle of operation

3 Design and principle of oper-
ation
The double-acting Type 3275 Pneumatic
Piston Actuator with 314, 490, and 804 cm²
actuator areas is mainly mounted on PSA
valves (e.g. Type 3241-PSA).
The actuator mainly consists of the base
(A4), cover (A10), and piston (A9). The stem
connector clamps connect the actuator's pis-
ton rod (A1) with the plug stem of the globe
valve.
S
A5
A9
A8
A7
A3
A2
A5
S
Yoke
A1
Fig. 2: Type 3275 Actuator (314 and 490 cm²)
10
The signal pressure p
F = p · A at the piston surface A, which is
st
opposed by the corresponding counter-
pressure. The piston is pressurized with the
supply air over the two connections (S, G
or G ½).
The actuators with 314 and 490 cm²
actuator areas are fixed to a yoke, which is
designed to accommodate a pneumatic or
electropneumatic positioner. See Fig. 2.
A10
A4
A1 Piston rod
A2 Piston rod seal
A3 Plain bearing
A4 Base
A5 O-ring
A7 Piston seal
A8 Piston guide band
A9 Piston
A10 Cover
S Signal pressure connection
creates the force
st
EB 8314 EN
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