Description
2-6
Part 1120277_01
E 2012 Nordson Corporation
Pressure Control Options
PURBlue 4 high-output melters have two different pressure control options
for maintaining maximum adhesive output pressure. When the melter is
dispensing adhesive, the system hydraulic pressure is governed by the
pressure drop through the manifold, hose, and applicator as affected by fluid
flow rate, fluid viscosity, and nozzle size(s). However, between products (or
any time the pump is turning but no adhesive is being dispensed) the pump
adhesive output is being recirculated to the reservoir through a hydraulic
pressure regulator that maintains the maximum hydraulic pressure. The
method of maintaining this hydraulic pressure can significantly affect the
adhesive application. Depending on the specific needs of an application, one
of the following pressure control options will provide optimum performance:
S Standard (X option): A melter with this option has a spring-balanced
manual pressure control valve (PCV) with which the operator can
easily set the maximum pressure by adjusting the preload of the
spring.
One way this option may be used is to meter a specific amount of
adhesive based on the pump rpm and displacement, in which case
the PCV is set to a high value and the pump speed changes (either
manually or automatically through the gear-to-line capability) based
on the output requirements.
S Pneumatic PCV with flow control bypass (F option): Amelter
with this option has a pneumatic PCV that is integrated with a
solenoid valve. An air pressure regulator and gauge located on the
drive cover assembly are used to set the air pressure to the
pneumatic PCV when the solenoid is in a non-energized state
(applicator-closed). When the solenoid is energized, the air pressure
to the pneumatic PCV is switched to the air supplied to the melter,
which in turn sets the system hydraulic pressure to the maximum
possible. On a melter with this option, the user provides only the 24V
signal—no additional air supply is required.
This option is typically set up such that the signal to the solenoid
valve is in common with the signal that opens the applicator so that
when the applicator is dispensing adhesive, the PCV is set to
maximum and the entire output of the pump is delivered through the
applicator. This allows for consistent, metered adhesive application
because the hydraulic pressure is consistent in both the
applicator-open and applicator-closed states.
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