Fluid Characteristics And Gun Performance; Operating The Spray Function; Operating The Electrostatics; Switching To The Higher Or Lower Kv Setting - Graco 236685 Instructions And Parts List

Fluid Characteristics and Gun Performance

For some fluids (especially metallic paints), measuring
the fluid resistivity is not always a reliable indicator of
paint performance in a spray gun. The voltage applied
by the resistivity meter is very low compared to the
voltage applied by the spray gun. Some conductive
components and additives in the fluid may exhibit
reduced resistivity when high voltage is applied by the
spray gun.
When testing a fluid to see if it will be suitable for
electrostatic spraying, it is important to measure the
spraying voltage when the fluid is flowing. The turbu-
lence created when the fluid is flowing helps to retard
the negative effects of the conductive components and
additives in the fluid.
The PRO 5500hc guns offer the capability of monitor-
ing the actual spraying voltage with the optional fiber
optic spraying voltage readouts. Either the kV only
readout or the kV and current readout can be very
helpful in monitoring the voltage characteristics when
spraying conductive fluids. Refer to Fig. 2, page 8.
To provide a smoother transition to the high voltage
and prevent some very conductive fluids from shorting
out, it may be necessary to operate the gun with the
voltage first turned to the lower kV setting, then switch
to the higher kV setting.

Operating the Spray Function

Applying a minimum of 50 psi (3.5 bar, 0.35 MPa) air
pressure to the gun manifold's cylinder air fitting (which
is marked "CYL", see page 7) will retract the gun
piston, which opens the air valves and a short time
later opens the fluid needle. This provides the proper
air lead and lag when triggering the gun. A spring
returns the piston when the cylinder air is shut off.

Operating the Electrostatics

To operate the electrostatics, air pressure is applied to
the gun manifold's turbine air fitting (which is marked
"TA", see page 7) through a Graco electrically con-
ductive air hose. The air enters the manifold and is
directed to the inlet of the power supply turbine (G).
The air spins the turbine, which then provides electrical
power to the internal high voltage power supply (H).
The fluid is charged by the spray gun electrode (J).
The charged fluid is attracted to the nearest grounded
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Introduction
object, wrapping around and evenly coating all sur-
faces.
The turbine air is exhausted into the shroud (D) and
out the back of the manifold through the fitting marked
"EXH". The exhaust air helps keep contaminants out
and helps keep the gun clean.
Switching to the Higher or Lower
kV Setting
The gun's full high voltage setting is 85 kilovolts. The
gun's spraying voltage can be reduced by switching to
the low voltage setting for spraying in areas where too
much electrostatic wrap is not desirable. Applying a
minimum of 50 psi (3.5 bar, 0.35 MPa) air pressure to
the kV switch air inlet (which is marked "KV", see page
7) will activate it and switch to the lower voltage set-
ting. The lower voltage is factory set to 60 kilovolts at
zero microamperes. This setting can be adjusted from
45 to 80 kilovolts, as instructed on page 35. The sole-
noid valve used to activate the kV switch must bleed
the air out of the line for the switch to draw back to the
higher voltage setting.

Gun Features and Options

D The gun is designed for use with a reciprocator,
and it can be directly mounted to a one-half inch
rod. With additional brackets, the gun can be
mounted for robotic applications.
D The gun is designed for quick-disconnect, which
enables the operator to quickly remove the spray
gun without disconnecting the fluid and air lines to
the gun.
D The gun functions are activated from a separate
controller that sends the appropriate signal to the
actuating solenoids (K). See Fig. 1, page 8.
D An optional fiber optic readout system can be
installed to monitor the gun's spraying voltage. A
fiber optic cable (V) connected to the gun manifold
carries the signal from the gun to a remote ES
(electrostatic) display module. See Fig. 2, page 8.
An ES Display Module (R), P/N 224117, is available
and will display the gun's spraying voltage and
current. A battery operated ES Display Module (S),
P/N 189762, is also available; it displays the gun's
spraying voltage only.