Parker CDAS HL 050 Series, Installation, Operation And Maintenance Instructions

Page: 42 / 75

41
Medium Flow Compressed Air Dryers - IOMI..
Moisture Override
In certain geographical locations, a dryer can be operated for extended periods with low amounts of water vapour in the inlet air (for
example, some countries can have an ambient temperature up to +40°C in summer and as low as -40°C in winter). As the dryer must
be sized for summer conditions, during winter, months, EST will save the user air, energy & money.
However, due to the way a desiccant bed adsorbs water vapour, during winter months with low levels of water vapour in the incoming
air, the saturation profile of the desiccant bed changes and a condition may occur where the bed becomes too saturated to be
regenerated by the standard purge regeneration cycle.
Therefore, the CDAS HL / OFAS HL / FBP HL controller also incorporates a safety feature to protect the desiccant material. The safety
feature, called Moisture Override activates after 30 minutes (1800 seconds), interrupting the ECO energy management function and
changing the drying columns over.
Once Moisture Override has been activated, the dryer will revert to a fixed timing cycle for 3 half cycles before going back into energy
saving mode (if the outlet dewpoint is again lower than the ECO setpoint). This allows energy savings to be realised without causing
damage to the desiccant bed.
The diagram below illustrates the EST timing cycle of a CDAS HL / OFAS HL / FBP HL operating at variable inlet conditions (EST
active, Moisture Override Activated).
Important Notes:
• When the drying cycle is being extended, “ECO” will be displayed on the controller screen.
• The length of time spent in “ECO” energy saving mode is dependent upon the moisture loading of the
incoming compressed air and the subsequent outlet dewpoint.
•
EST energy saving mode can extend the drying cycle from 180 seconds (3 minutes) up to 1800 seconds
(30 minutes).
•
When moisture override is active, the “MO” icon will be displayed below the outlet dewpoint.
• The number after MO denoted the number of ½ cycles remaining before the dryer can once again enter
“ECO” energy saving mode.
•
The default moisture override time of 1800 seconds (30 minutes) and the subsequent activation of the
standard timing cycle for 3 half cycles can be modified by a trained engineer (please note, that changing these
parameters can affect the performance of the dryer and should only be carried out following consultation with
Parker)
Purge Economy
Purge economy requires a physical connection between the air compressor and the dryer and is designed to save energy (by stopping
purge air) when the air compressor goes off load. There are two modes for purge economy.
• Mode 1
(Option) – When Purge Economy is activated, the dryer continues until the end of the regeneration cycle, closes the
exhaust valve then stops the cycle after repressurisation of the off-line column.
• Mode 2
( Default ) - When Purge Economy is activated, the dryer immediately closes the exhaust valve to repressurise the off-line
column then stops the cycle.
Important Notes:
• EST & Purge economy can be used together.
• Purge economy takes priority over EST .
• Purge Economy – (
Default
): If dryer is in EST ECO mode and the compressor goes off-load, purge
economy is activated and the dry will immediately stop (Mode2)
• Purge Economy – (Option): If dryer is in EST ECO mode and the compressor goes off-load, purge
economy is activated and the dry will continue to the end of its ½ cycle then stop (Mode 1)
• Once the compressor is brought back on-load, the dryer will immediately change over and resume drying
on the opposite column
• When purge economy is active, the green ECO icon will be displayed.
1
2 Colum
n
Drying
Repres-
surisation
Energy Savings Regeneration
Regeneration
1800
180
1
1800
180
0
Drying
Repres-
surisation
150
Drying
Regeneration
Repres-
surisation
Regeneration
180
1 180
0
Drying
Repres-
surisation
150
180 150 180 150 1
180
EST Moisture Override Cycle (Activated after 30 Minutes in ECO)
ECO Cycle (Moisture Override Activated after 30 Minutes) Standard 1/2 Cycle Standard 1/2 Cycle Standard 1/2 Cycle
0
0 0
Seconds