12.9.10 If the Purge Flow is low (this is the portion
of the dry air that is required from the drying tower
to regenerate the off-line tower) then a humidity
alarm will likely occur. To correct the problem,
remove the Dry Pak towers from the Air Dryer, DO
NOT readjust the Purge Adjuster. Remove the upper
center block and soak the block with a degreaser/
cleaner and thoroughly rinse with water. Dry off
and reinstall. See paragraph 11.8 for instructions to
remove the Dry Pak. As an alternative to removing
and cleaning the block, call the factory for eld
adjustment procedures to increase purge settings.
12.10 LOW SYSTEM PRESSURE
SHUTDOWN ALARM
12.10.1 The low system pressure shutdown alarm
will occur should the system pressure fall below 15
psi. During a start-up sequence, there is a 45 second
delay before shutdown occurs, otherwise 10 seconds
of delay while in RUNNING condition. The LCD
will display a MAJOR alarm condition (solid Red
LED) with posted time and date of the occurrences.
12.10.2 A major air leak, such as from failure to
restore a hose after some maintenance procedure,
can cause Low System Pressure Shut down. Small
leaks, even if numerous, would not be the cause of
Low System Pressure Shutdown.
12.10.3 If either Purge Valve (7) is worn and sticks in
the open position, Low System Shutdown will occur
when the opposite Purge Valve is opened by the cycle
timing that is controlled by the sensor board. Install
repair kits (see Fig. 9) to both purge valves.
12.10.4 Having performed the procedures outlined
above, should the Low System Pressure Shutdown
alarm remain active, connect a test gauge to the test
valve in the tting at the top of the Water Sight Tube
(24), to verify the actual System Pressure. If the test
gauge veries normal System Pressure, check the red
supply tube which is routed from the Water Separator
Tank (35) to the System Pressure Sensorfor a crimp
or an obstruction.
12.11 HIGH SYSTEM PRESSURE
SHUTDOWN ALARM
12.11.1 The High System Pressure alarm will
occur should the system pressure rise above 40 psi.
The LCD will display a MAJOR alarm condition
(Solid Red LED) with posted time and date of the
occurrence.
12.11.2 A mis-adjustment of the system pressure and
purge valve not opening may cause the pressure to go
above 40 psi. Readjust the system pressure regulator
and verify the purge valve cycle. A major blockage
or crimped hose leaving the water separator tank and
entering the Dryer Tower inlet is another possibility.
Verify and correct as required.
12.11.3 Should the High System Pressure remain
active, connect a pressure test gauge to the test valve
in the tting on top of the water sight tube (24) and
verify the actual system pressure. If the reading is
off, the system pressure sensor on the sensor board
could be damaged or a problem exists with the circuit
board. Replace the sensor board.
12.12 LOW LINE PRESSURE ALARM
12.12.1 Low Line Pressure Alarm will occur
should the LINE pressure fall below its set pressure.
The LCD will display a MINOR alarm condition
(blinking Green/Red LED) with posted time and date
of the occurrence. Should the condition clear on its
own, the MINOR Alarm will automatically reset.
12.12.2 Low Line Pressure Alarm can be the result
of maladjusted or defective Line Pressure Alarm
Sensor, or simply an incorrectly adjusted Line
Pressure Regulator (29). Check the adjustments of
the alarm points (paragraph 8.3). Verify the accuracy
of the Line Pressure by connecting a test gauge to
the Test Valve on the Line Pressure Regulator. If the
dehydrator output air ow, shown on the display
is very close to maximum, it may be impossible to
increase the Line Pressure and alarms may come and
go because of changes in ow created by day/night
temperature swings, or because of cable repair work.
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