Logix
®
520MD+ and 510+ Digital Positioners FCD LGENIM0105-15-AQ – 05/16
24
6 TUBING
After mounting has been completed, tube the positioner to the actu-
ator using the appropriate compression fitting connectors. For best
performance, use 10 mm (3/8 inch) tubing for 645 square cm (100
square inch) actuators or larger. See Figure 24 below.
6.1 Determine Air Action
The port labeled “Y1” delivers air when an air supply is present and
the relay is energized. (For positioners with double acting relays,
this is port A. For positioners with single acting relays, this is port
B.) Typically, the port labeled “Y1” should be tubed to the pneumatic
side of the actuator (the side that would result in the air compressing
the actuator spring). When tubed this way, the spring is designed to
return the valve to the fail safe state should supply air or power to the
unit fail.
Tube the port labeled “Y1” to the side of the actuator that must receive
air to begin moving away from the fail safe state.
If air from “Y1” should open the valve, set the Air Action configuration
switch on the positioner to Air-to-Open, otherwise set it to Air-to-
Close.
The Air-to-Open and Air-to-Close selection is determined by the actua-
tor tubing, not the software. When air action selection is made during
configuration, the selection tells the control which way the actuator
has been tubed.
If the valve is double acting, port the valve labeled “Y2” to the other
side of the actuator.
c
DANGER:
Proper tubing orientation is critical for the positioner to
function correctly and have the proper failure mode.
Example: Tubing Linear Double-Acting Actuators
For a linear air-to-open actuator, the “Y1” port of the positioner is
tubed to the bottom side of the actuator (closest to the valve). The
“Y2” port of the positioner is tubed to the top side of the actuator. See
Figure 20. For a linear air-to-close actuator the tubing configuration is
reversed.
Figure 20: Linear, Double Acting, Air to Open
Example: Rotary Double-Acting Actuators
For a rotary actuator, the “Y1” port of the positioner manifold is tubed
to the far side of the actuator. The “Y2” port of the positioner manifold
is tubed to the side of the actuator closer to the transfer case. This
tubing convention is followed regardless of air action. On rotary
actuators, the transfer case orientation determines the air action. See
Figure 21..
Figure 21: Rotary, Double Acting, Air to Open
Example: Tubing Single-acting Actuators
For single-acting actuators, the “Y1” port is always tubed to the pneu-
matic side of the actuator regardless of air action. If a double acting
(spool style) relay is installed in the positioner, plug port B (Y2). If a
single acting - poppet style relay is installed, plug port A (Y2) as in
Figure 22. Or, port A may be used for purging. See Purging Single
Acting Actuators below.
