Logix™ 3800zb Digital Positioner FCD AIIOM001030_EN 02/23
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5 INSTALLATION - TUBING
5.1 Direct Mount
After mounting to the actuator, tube the 4-Way valve block port
connections to the actuator using the appropriate fitting
connectors. For best performance, use 10 mm (3/8 inch)
tubing for 645 square cm (100 square inches) actuators or
larger.
5.2 Determine Gas Supply Action
Connections using a 4-Way valve block for actuator control,
are shown in Figure 6.
Figure 6: 4-Way valve actuator connection
When a pneumatic supply is present at port “1”, and the
solenoid for port “4” is energized, port “4” delivers gas.
Typically, the tubing from port “4” is connected to the side of
the actuator that results in the gas compressing the actuator
spring. When tubed this way, the spring is designed to return
the valve to the fail-safe state should supply gas or power to
the unit fail or be turned off.
Tube the port labeled “4” to the side of the actuator that must
receive gas to begin moving away from the fail-safe state.
If gas from “4” should open the valve, set the Air Action
configuration DIP 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 only a reflection of the tubing. When
selecting air action during configuration, the selection tells the
control which way the actuator was tubed.
If the valve is double acting, port the valve labeled “2” to the
other side of the actuator, otherwise plug port “2”.
DANGER: Proper tubing orientation is critical for the
positioner to function correctly and have the correct failure
mode. The backward tubing could cause an unsafe failure
mode.
Example: Tubing Linear Double-Acting Actuators
For a linear air-to-open actuator, the tubing from port “4” is
connected to the bottom side of the actuator (closest to the
valve). Tube the “2” port of the positioner to the top side of the
actuator. See Figure 7: Linear, Double Acting, Air to Open. For
a linear air-to-close actuator the tubing configuration is
reversed.
Figure 7: Linear, Double Acting, Air to Open
Example: Rotary Double-Acting Actuators
For a rotary actuator, route tubing from Port “4” to the far side
of the actuator and tubing from port “2” to the side of the
actuator closer to the transfer case. Follow this tubing
convention regardless of air action. On rotary actuators, the
transfer case orientation determines the air action. See Figure
8: Rotary, Double Acting, Air to Open.
Figure 8: Rotary, Double Acting, Air to Open
Example: Tubing Single-Acting Actuators
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