Graco PrecisionMix ii, Instructions And Parts List

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Operation 4–15
Operation
Flow Control Operation
Initial Setup
1. See page 8–16 for flow control setup.
2. See page 8–19 to set the Delay Time to 9.9 sec-
onds.
3. See page 9–16 to set the Gain Factor. For Fluid
Regulator Part No. 830–35X, set the gain to 250.
4. See page 6–5 to enter the flow rate setpoint. If
Analog Inputs is selected, set the desired flow rate
setpoint from the robot or other source.
5. While monitoring the Flow Rate Setpoint screeen
(page 6–5), trigger the gun (airflow switch) until
flow rate is close to the setopint. Release the gun
trigger.
6. Trigger the gun on for another 30 seconds. Make
sure the flow rate is still close to the setpoint.
Repeat step 5, if necessary.
7. While the gun trigger is off, change the setpoint to
a different value.
8. While monitoring the flow rate screen, trigger the
gun on for 10 seconds.
a. Setpoint change from a small value (300
cc/min.) to a larger value (500 cc/min.):
If the flow rate during the first 10 seconds
is below the new setpoint, increase the
Gain Factor by 50.
If the flow rate during the first 10 seconds
is above the new setpoint, decrease the
Gain Factor by 50.
b. Setpoint change from a large value (600
cc/min.) to a smaller value (400 cc/min.):
If the flow rate during the first 10 seconds
is below the new setpoint, increase the
Gain Factor by 50.
If the flow rate during the first 10 seconds
is above the new setpoint, decrease the
Gain Factor by 50.
9. Repeat steps 6–8 until an optimum Gain Factor is
achieved.
10. Change the Delay Time to an appropriate value.
too short of a delay time will create inaccurate
initial flow rate reading after the gun is triggered.
Flow Control Tips
Always keep a balanced fluid inlet pressure be-
tween component A, component B, and component
C. This will prevent the fluid pressure regulator from
opening or closing every time the PrecisionMix
system switched from A valve to B valve to C valve.
Do this by adding a manual fluid regulator for each
of the fluid supply inlet. Also, try to adjust the
dispense valve opening. Refer to the Plural Compo-
nent Mix Manifold manual 308288.
Keep the gun trigger on as long as possible during
spraying. This will give the PrecisionMix system
more time to adjust the fluid regulator to get to the
flow rate setpoint. If the gun delay time is set at 1.0
second, and the gun trigger is on for 2.0 seconds,
then the PrecisionMix system has only one second
to do any flow control.
Add an inline flow meter with high–resolution pulse
output in the mixed material stream. Note that any
flow meter installed in the mixed material stream
may experience a flushing/clearing problem.