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3
781S Series Spray Valve
How the Valve Operates
Input air pressure at 70 psi (4.8 bar) retracts the needle
from its nozzle seat,
allowing liquid to flow from the
nozzle. At the same time, nozzle air is turned on and
flows from the anannulus
around the liquid nozzle. This
adjustable nozzle air creates a pressure drop around the
nozzle, causing the liquid to atomize into fine droplets.
The amount sprayed is controlled by the valve open time,
reservoir pressure, and needle stroke*. Area of coverage is
determined by the nozzle size and the distance between
the nozzle and work surface.
ValveMate Concept
The ValveMate
™
8040 provides easy adjustment of
spray valve output for maximum end-user convenience
and efficiency. Valve open time is the primary control of
deposit size. The ValveMate 8040 puts adjustment of
valve open time where it needs to be — near the spray
valve.
External solenoids, combined with a 0–2 bar (0–30 psi)
nozzle air pressure regulator, provide Low Volume
Low Pressure (LVLP) air to the nozzle, for high transfer
efficiency.
SPRAY VALVE CONTROLLER
8040
NOTE:
Order your single or dual valve solenoid
assemblies separately. Consult Nordson EFD for
recommendations.
The primary control of deposit size is the valve open time.
closed
open
1
2
3
1
2
3
Calibration Feature
The stroke control reference ring of each 781S-SS valve
is factory calibrated to the zero position. After cleaning,
disassembly and reassembly, the stroke control zero position
may require recalibration. To do so:
1. Make a note of the current
stroke setting number.
2. Turn the calibration
adjustment knob (inner)
counterclockwise two full
turns.
3. Turn the stroke knob (outer)
clockwise until it stops.
Note reference ring “0”
(zero) location. If “0” is not
positioned above either
reference mark on air cylinder body, rotate outer stroke
knob counterclockwise until “0” is positioned above
preferred referencemark. Select reference mark that is
more clearly visible based on valve mounting location.
4. Insert 1/8" hex allen wrench (included) into calibration
adjustment knob.
5. Turn the calibration adjustment knob clockwise until it
stops. The stroke adjustment is now calibrated to zero.
6. Reset stroke to the required position noted in step 1.
4
2 5
1
6
3
*The 781S valve can be ordered in a tamper-resist
configuration to limit unauthorized adjustment. Specify
part #7021619 or #7021616.
