Annunciator. The Variable Cycle Switch must be set to the 100% load setting and the Demand Control
switch ON, for the Pro Purge to work! If the dryer is maintaining a good dew point AFTER the first five
minutes of drying, the Pro Purge will override the fixed cycle and keep the current tower on-line until it is
saturated to design loading (switch point value), usually -40°. If this occurs, the Powersaver Active light
and the -40 light on the Sequence Annunciator will be on and the off-line bed which has just finished
being regenerated will repressurize and be ready to go on-line. Once the dew point degrades to the
switch point value, the freshly regenerated bed will go on-line, and the saturated bed will depressurize
and begin regeneration. Note that the Pro Purge can not shorten the cycle. The drying tower will always
be on-line a minimum of five minutes and the regenerating tower will always undergo a design
regeneration cycle of 4 minutes & 15 seconds. Thus the Pro Purge can only compensate for “under”
loading, not overloading conditions.
If there is any error with the Pro Purge sensor or cable the alarm light only will be lit and the dryer will
default to the fixed time cycle. If the dew point is -20 the alarm light will be on as well. There is also a
Demand Control On/Off switch located on the Sequence Annunciator. If this switch is turned “off” the
dryer will operate in the fixed time cycle. The Pro Purge will continue to display dew point. The Pro
Purge is fully programmed, wired and installed at the factory if ordered with the dryer.
For dryer start-up, all that is normally required is a 24 hour run period for the dryer before the isolation
valve to the probe is open. This assures the sensor will see dry air for its first exposure to the system.
Dryers Equipped with a Powerloc
The Powerloc is a Digital Dew Point Monitor. The sensor is a thin film gold aluminum oxide design. The
Powerloc monitors the outlet pressure dew point of the dryer and digitally displays it. The Powerloc
feature tailors the dryer cycle to actual loading conditions, minimizing energy usage. Without the
Powerloc, the cycle is fixed and “worst case” design conditions are assumed.
The Demand Cycle is accomplished by providing a discrete dry contact closure across the Cycle Loc
terminals on the Sequence Annunciator. The Variable Cycle Control Switch must be set to 100% load
setting for the Powerloc to work. If the dryer is maintaining a good dew point AFTER the first five
minutes of drying, the Powerloc will override the fixed cycle and keep the current tower “on-line” until it is
saturated to design loading (switch point value), usually -40°F. If this occurs, the “off- line” bed which has
just finished being regenerated will repressurize and be ready to go “on-line”. The Cycle Loc light on the
Sequence Annunciator and the Powerloc will be on at this time. Once the dew point degrades to the
switch point value, the freshly regenerated bed will go “on-line”, and the saturated bed will depressurize
and begin regeneration. Note that the Powerloc can not shorten the cycle. The drying tower will always
undergo a design regeneration cycle of 4 minutes and 15 seconds. The Powerloc can only compensate
for under-loading, not overloading conditions.
If there is any error with the Powerloc, the dryer will default to the fixed time cycle. There is also a
Powerloc On/Off switch located in the control enclosure. If this switch is turned off the dryer will operate
in the fixed time cycle. The Powerloc will continue to display dew point. The Powerloc is fully
programmed and wired at the factory if ordered with the dryer.
For dryer start-up, all that is normally required is sensor installation. The sensor should be installed after
dryer has been allowed to purge the initial dusting caused by transportation or filling. The probe
isolation valve should be fully opened after installation to allow operations at full line pressure for correct
reading of pressure dew point. A coil of capillary tubing is provided to allow a small sample flow over
the sensor and prevent ambient moisture from infiltrating the system. Check the bleed periodically to
ensure it is not clogged.
Following sensor installation, allow the sensor to stabilize at the line pressure for four hours prior to
attaching the sensor cable.
Failure to follow the above precautions may result in sensor failure not covered by warranty.
Please note that upon installation the sensor will be saturated at atmospheric conditions. Even if the
dryer is producing a good dew point, it will not be indicate
d immediately as it will take a period of time
for the sensor to dry out and come to equilibrium with the system.
The sensor will also become saturated to atmospheric conditions if the air system is shut down and
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