Ransburg DynaFlow User Manual - Manual (Page 60)

LN-9400-00.9
DynaFlow TM User Manual - Operation
56
3. Total system shutdown, including AC power,
air and fluid pressure is recommended if the
system is to be shutdown for more than one
shift.
Clean Mode
CLEAN mode can only be initiated if the GUN has
been given a Halt input and is enabled and no faults
are active. Each CHANNEL can be independently
configured to accept the CLEAN command. For
two-component GUNs, it may not
be desirable to clean both the resin and catalyst at
the same time, therefore each CHANNEL can be
configured as a “clean” CHANNEL independently
by setting the Clean CHANNELs parameter in the
GUN configuration table.
The CLEAN operation can be started one of several
ways. The first method is to simply supply the GUN
CLEAN input. The second method is to initiate the
CLEAN mode through the OPERATOR INTER-
FACE or host controller (refer to the appropriate
manual). Actual cleaning time and sequences,
including soft air push-out (purge) is performed by
the system controller or the pneumatic interface
panel, and not directly by the fluid flow controller.
The CLEAN mode is terminated when deactivated
from the Operator Interface or when a HALT signal
is supplied.
Calibrate Mode
CALIBRATE mode can only be initiated if the
GUN is enabled and no faults are active. The
CALIBRATE operation is initiated and controlled
through the OPERATOR INTERFACE or host con-
troller (refer to the appropriate Operator Interface
or Programming manual).
The CALIBRATE mode is terminated when deacti-
vated from the Operator Interface or if the Enable
input is removed.
Recovering From Faults
This section:
• Identify and record the fault
• Evaluate action(s) to be taken
• Perform corrective action(s)
• Reset and run
PID CONTROL
The ransburg DynaFlow Fluid Flow Controller
incorporates a form of a Proportional-Integral-
Derivative (PID) algorithm with additional func-
tions or modifications which are specific to the
efficient control and delivery of materials in paint
spray applications. PID is the most widely used
method for closed loop controllers in all areas of
industrial control.
The PID control algorithm develops a control signal
composed of three elements. The proportional
element is simply proportional to the difference
between the current fluid flow and the desired fluid
flow, referred to as the error. The integral element
of the control output is proportional to the integral
of the error signal, and the derivative element is
proportional to the derivative of the error signal.
These are explained in more detail below. A general
understanding of how a PID controller works will
be beneficial in producing the best overall fluid flow
response from the fluid delivery system. This can
lead directly to reduced paint usage and higher
quality of finish.
Largely the air and fluid control components and
their placement with respect to each other deter-
mine limitations on general fluid flow response.
This includes the following:
• Type of fluid regulator and needle or dia-
phragm ratio (pilot pressure vs. fluid pres-
sure).
• Rheology of the fluid(s) such as viscosity,
and shear.
• Length and diameter (volume) of the air pi-
lot lines from the V/P or I/P transducer to
the fluid regulator.
• Back pressures created by fluid control
devices such as the applicator fluid pas-
sage restrictions.
Error
The difference between the requested (set point)
value and the actual process being controlled.