Table of Contents
Advertisement
3 Design and principle of operation
The SAMSON ROTACTOR RP 3171 actuators are devices for
remote operation (on/off or modulating duties) of different in-
dustrial valves such as ball valves, butterfly valves and plug
valves.
The actuators are available in two configurations: spring re-
turn and double acting.
1. DOUBLE ACTING
Refer to Fig. 3-1.
In case of the double acting configuration air pressure will be
necessary for both strokes (A and B).
A
"2"
B
"2"
Fig. 3-1
2. SINGLE ACTING
Refer to Fig. 3-2.
When air pressure is supplied through port "2" (A') into the
actuator body, the linear force applied on the piston surface
generates the pinion rotation, driving the valve to a defined
position. At the same time the actuator springs are compres-
sed.
When air pressure is discharged (B'), the springs are auto-
matically released, driving the rack and pistons back to the
original position and thus the valve to the fail-safe position.
A'
"2"
B'
"2"
Fig. 3-2
EB 8325 EN
"4"
"4"
"4"
"4"
The actuators can be controlled by different options:
− direct mounting of control devices (for example a solenoid
valve or a manifold) with NAMUR interface,
− threaded connections (to pressurize port "2" and "4") wi-
th air lines from separate electro-pneumatic control sys-
tem.
3.1 Direction of action and fail positions
The standard rotating direction for the SAMSON ROTACTOR
RP 3171 actuators is clockwise to close.
Standard SAMSON ROTACTOR RP 3171 actuators are
designed for 90° rotating angle, with travel stop allowing
adjustment (Fig. 3-3) for -5° up to +15° on the close position
and for +5° up to -15° on the open position. For AT045U
stroke adjustment is only available on request.
90°
95°
75°
Fig. 3-3
For single acting actuators in case of pressure, power or
signal failure the springs drive the actuator in the fail position
that can be FAIL OPEN or FAIL CLOSE.
Note
If the actuator is controlled by a control system the FAIL positi-
on may be different from FAIL OPEN or FAIL CLOSE.
Î Refer to the actuator model technical data for the FAIL po-
sition.
Î Refer to section 2.1 'Actuator nameplate sample' (Table
2-1, position 11) for the fail action and direction of rotati-
on available options.
Design and principle of operation
Available stroke
adjustment
15°
0°
-5°
3-1
Advertisement
Table of Contents
