Dual Ram Cross-Over Control Function; X-Over Overview - Graco Therm-O-Flow Plus HM55-D Series Instructions Manual

Dual Ram Cross-Over Control Function

If your Therm-O-Flow Plus system has cross-over
control boxes (243254) installed on each unloader
assembly (A) and (B), the X-Over functions of the
pendant are functional. The unloaders are typically
shipped pre-installed at the Graco factory with label (A)
and (B) placed on the upper left hand corner of the
main control box. See Fig. 13.

X-Over Overview

The cross-over control functions of the pendant allow
dual (2) drums to operate where if one drum (DRUM
A) activates the LOW limit switch, the other drum
(DRUM B) is preheated, readying itself for when
DRUM A goes empty. When DRUM A goes EMPTY,
the active drum will now be DRUM B. The air solenoid
for DRUM A is turned off and the DRUM B air solenoid
is allowed to come on if all the zones are up to temper-
ature. DRUM A will stay hot for 1 hour, allowing the
operator time to get a new drum and change the drum.
Once 1 hour has passed, DRUM A zones will automat-
ically shut off. The operator will change the drum by
pressing the F4 (X0) selection on the MAIN menu.
The operator will be prompted to CHANGE DRUM A
and the heat zones and the air motor solenoid will be
started, if still not running). The operator will change
the drum as normal. When done with the drum
change, the operator will acknowledge the change with
the pendant by pressing the appropriate DONE key
and the zones and solenoid will shut off for DRUM A.
X-Over functions the same going from DRUM A to B or
vise versa.
If the active drum goes LOW and the other drum has
not been changed since being empty, the AMBER light
of the drum to be changed will begin to flash off/on,
alerting the operator to change the drum.
44 309085
NOTE: The air solenoid is allowed to turn on by the
x-over controls. The solenoid is not on until all the
zones are within the operating temperature window.
NOTE: The 7 Day Timer settings take precedence
over all functions of the X-Over. If the 7 Day Timer is
on but the current time is outside the Start/Stop time
operating window, all the zones will be off and the
X-Over will not operate until the current time is within
the operating time window of the 7 Day Timer.
Each unloader has it's own X-Over control box with a 3
light beacon and a dual limit switch assembly. The first
light is a GREEN light. When this is illuminated, that
unloader is the ACTIVE UNLOADER and the solenoid
to the air motor is on, allowing the pump to move
material to the dispense point. The AMBER light is the
LOW light; it will illuminate when the low level switch is
activated. The RED light is the EMPTY light and will
illuminate when the drum empty switch is activated.
Each unloader assembly has been marked from the
factory indicating whether it is UNLOADER A or UN-
LOADER B by a letter mounted on the upper left hand
side of the control box. The A unloader will have it's
temperature controllers addressed 1 thru 6 for 6 Zone
control panels (1 thru 8 for 8 Zone panels). The B
unloader will have it's temperature controllers ad-
dressed 7 thru 12 for 6 Zone control panels (9 thru 16
for 8 Zone control assemblies). The labels on the
front of the control panel have not been changed and
do not reflect the proper zone addresses.