Samson 3730-4 - Defining the Valve Closed Position

5.1 Defining the valve closed
position
To adapt the positioner to the operating di
-
rection of the actuator, set slide switch to AIR
TO OPEN or AIR TO CLOSE.
AIR TO OPEN = Signal pressure opens the
valve, for fail-safe position: actuator stem
extends/fail close
AIR TO CLOSE = Signal pressure closes the
valve, for fail-safe position: actuator stem re
-
tracts/fail open.
The switch position is prompted prior to an
initialization. After an initialization has been
completed, changing the switch position
does not have any effect on the operation of
the positioner.
The positioner only needs to be initialized
again after the direction of action of the ac-
tuator has been changed.
5.2 Setting the volume restriction Q
The volume restriction Q is used to adapt the
air delivery to the size of the actuator:
4
Actuators with a transit time < 1 s, e.g.
linear actuators with an effective area
smaller than 240 cm², require a
restricted air flow rate (MIN).
4
Actuators with a transit time
≥
1 s do not
require the air flow rate to be restricted
(MAX).
The position of volume restriction Q also de
-
pends on how the signal pressure is routed
at the actuator in SAMSON actuators:
4
The SIDE position applies for actuators
with a loading pressure connection at the
side, e.g. Type 3271-5.
4
The BACK position applies for actuators
with a loading pressure connection at the
back, e.g. in Type 3277-5.
The SIDE restriction position always applies
for actuators from other manufacturers.
Overview · Position of volume restriction Q*
Signal
pressure
Transit
time < 1 s
≥
1 s
Connection at the side MIN SIDE MAX SIDE
Connection at the back MIN BACK MAX BACK
* Intermediate positions are not permitted.
Note: The positioner needs to be initialized
again after the position of the restriction has
been changed.
EB 8384-4 EN 59
Start-up and settings
MAX BACK
MIN SIDE
MIN BACK
MAX SIDE
Q
Fig. 24 · Volume restriction Q
MAX BACK/MIN SIDE setting