How The Valve and Controller Operate
open position
The 780S is a normally closed, air actuated needle
type spray valve that uses a Low Volume Low
Pressure (LVLP) design for high transfer efficiency
without overspray or airborne mist.
Air pressure from the VALVEMATE
™
7040 controller at
70 psi (4.8 bar) acts on a piston
➀
that retracts the nee-
dle ➁ from its nozzle seat ➂ and allows liquid to flow
from the nozzle ➃. At the same time, nozzle air, also
from the 7040, is turned on and flows from an annulus
➄ around the liquid nozzle.
This adjustable nozzle air creates a pressure drop
around the nozzle, causing the liquid to atomize into
fine droplets.
When the timed actuating air from the 7040 shuts off,
the piston spring moves the needle onto the nozzle
seat, shutting off liquid flow. A preset nozzle air delay
ensures that no liquid remains on the nozzle after the
valve closes, eliminating after-deposit spatter.
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 dis-
tance between the 780S nozzle and the work surface.
closed position
4 / How The Valve and Controller Operate
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