Flowserve StarPac II Control Valves - Manual (Page 26)

Air Action - Used to set up the StarPac II for the configured actuator
failure mode. ATO (Air-to-Open) is normally used for fail-closed
valves, ATC (Air-to-Close) is normally used for fail-open valves. If
ATC is selected and you will be using an analog command source,
configure the analog command to reverse so that 4 mA equals the
100 percent position (open). The following table lists the possible
configurations:
Failure Mode
Output 2
(bottom port) Is
Connected to: Output 1 (top
port) Is
Connected to: Spring
Failure
Position Air
Action
Air loss, fail-closed:
Power loss, fail-
closed actuator top actuator bottom above
piston
ATO
Air loss, fail-closed;
Power loss, fail-open actuator bottom actuator top above
piston ATC
Air loss, fail-open;
Power loss, fail-open actuator bottom actuator top below
piston ATC
Air loss, fail-open;
Power loss, fail-close actuator top actuator bottom below
piston
ATO
Low Air - This option is used to set the trip parameters for low
supply air to the system, which is continuously monitoring the air
supply in the actuator. Using the actuator pressures, the StarPac II
can infer the supply pressure to within five to 10 psi. If the supply
pressure drops below the Low Air Trip Pressure then the positioner
will attempt to hold the valve for the time specified in the hold
parameter and then ramp to the spring failure position at the
specified Low Air Ramp Rate.
Softlimits - (Softlimits are stroke limits set and maintained by the
system’s electronics or software. These limits are only in effect
when the unit has power and is not in Test mode. When power has
failed or cut off to the StarPac II, the valve will fail to its mechanical
stops or limits.) This option allows you to set software limits on the
travel of the valve. These limits are active in Auto and Manual
modes, but they do not affect failure modes. Normally these limits
are set to -10 and 110 percent of travel so they do not affect valve
operation.
Units -The StarPac II system has individually configurable units for
Process Pressure, Liquid flow, Gas flow, Process temperature, and
actuator pressure. Units for each type of process variable are set in
the Unit menu. (See Figure 8)
Next Soft
Lmts
Unit Tag
Name
Proc
Pres Liq
Flow Gas
Flow Next
Proc
Temp Act
Pres
Figure 8: Units Menu
StarPac II User Interface Manual 20