Ransburg RMA Direct A12867 - Manual (Page 50)

RMA-303 Direct Charge - Operation
47 LN-9266-11.3
(See “Circuit Diagram” in the “Introduction”
section.) The fluid valves in the RMA-303 are
actuated by an air signal. The air pressure
must be greater than 70 psi (482.6 kPa) to as-
sure 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 30,000 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 pres-
sure.
The solvent valve controls the flow of cup
wash solvent. When actuated, solvent flows
through a separate fluid tube passage and into
the bell cup. This provides cleaning of the in-
side of the bell cup. The outside of the cup is
simultaneously cleaned by a nozzle mounted
on the shaping air ring and shroud. The sol-
vent valve should never be triggered at the
same time as the paint trigger valve to prevent
solvent from flowing backward into the paint
line.
To color change the applicator, a solvent air
chop must be provided through the main paint
line (see ”Typical Installation RMA-303” in the
Installation” section).
!
C A U T I O N
•
The normal fluid flow range is 25-700 cc/min.
During a color change or when flushing the
system, high 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 as-
sembly or front shroud.
•
High voltage must be interlocked with the
solvent valve to prevent solvent spraying
while high voltage is on.
TURBINE SPEED
Turbine speed is determined by the input air
pressure/flow at the rear of the atomizer.
Turbine speed is intended to be closed loop
controlled using the fiber optic speed transmit-
ter, 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.)
N O T E
The bell rotational speed determines the quali-
ty 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 at-
omization. Excessive speed reduces trans-
fer efficiency!
!
W A R N I N G
•
DO NOT exceed the maximum rated operat-
ing speed and turbine inlet pressure. Exces-
sive speed may cause air turbine damage or
damage to the bell.