Ransburg RMA Dual Purge Direct A12300 - Manual (Page 47)

DUAL PURGE SPRAYING
The RMA-303 has dual purge capability. This
means the applicator can continue to spray paint,
at voltage, while side "B" or "Paint 2" is being
flushed or cleaned. To operate in the dual purge
mode, two (2) separate color valve systems
must be installed.
TURBINE SPEED
Turbine speed is determined by the input air pres-
sure/flow at the rear of the atomizer.
Turbine speed is intended to be closed loop
controlled using the fiber optic speed transmitter,
located on the turbine manifold. A speed input
to a remote speed controller, such as the Serial
Atomizer module, is required (see "Speed and
Pressure Charts" in the "Introduction" section).
RMA-303 Dual Purge/Direct Charge - Operation
42
FLUID VALVE CONTROL
(Trigger, Dump & Solvent)
(See "Figure 5 and Figure 6 - Circuit Schematic"
in the "Intro-duction" section.) The fluid valves in
the RMA-303 are actuated by an air signal. The
air pressure must be greater than 70 psi to assure
proper actuation of the valve. Applying air to the
valve actuator turns on the fluid or air for that valve.
The paint trigger valve controls the paint flow to
the bell. When actuated, paint flows through the
valve to the fluid tube, and into the rear of the
bell cup. The bell cup must be spinning at least
20,000 rpm when fluid is turned on to enable the
fluid to flow through the bell paint passage and
be atomized.
The dump valve controls the paint flow through the
dump line. When actuated, paint flow is directed
to the dump return line. This provides a method
of rapidly removing paint from the incoming line
for cleaning and/or color change. Normally, the
dump valve is not actuated at the same time as
the paint trigger valve since the trigger valve is
intended to cause the fluid to flow to the bell at
the prescribed input pressure.
The solvent valve controls the flow of solvent
through the valve manifold, fluid coil, and fluid
tube. When actuated, solvent is allowed to enter
the valve manifold to allow cleaning of the fluid
coil and fluid tube. It also provides cleaning on the
inside of the bell cup. Solvent flow through this
valve must be restricted to 700 cc/min. or less. It
is also more effective to use and air/solvent chop
during the cleaning process. The solvent valve
and the paint valve should never be actuated at the
same time in order to prevent cross contamination.
The solvent line for the cup wash (CW) feature
is a pass through passage in the applicator and
must be controlled by external valving in the color
stack. This line must be purged with air before
continuing to spray at high voltage.
Ransburg
LN-9263-08.5
† The normal fluid flow range is 25-700
cc/min. During a color change or when
flushing the system, higher flow rates may
be required. However, the maximum flow
rate through the bell cup must not exceed
700 cc/min., to avoid solvent or paint from
flooding into the internal portion of the air
bearing motor assembly or front shroud.
† High voltage must be interlocked with
the solvent valve to prevent solvent spraying
while high voltage is on.
C A U T I O N
!
† Never perform the interior/exterior cup
clean process with high voltage on.
W A R N I N G
!
NOTE
† The bell rotational speed determines
the quality of atomization and can be
varied for various paint flow rates and
paint formulations. For optimum transfer
efficiency and spray pattern control, the
bell rotational speed should be set at
the minimum required to achieve proper
atomization. Excessive speed reduces
transfer efficiency!