Parker CDAS HL 050 Series, Installation, Operation And Maintenance Instructions, Page: 41 / 75

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Medium Flow Compressed Air Dryers - IOMI.
EST – Energy Saving Technology (Also known as DDS or Dewpoint Dependent Switching)
Each CDAS HL / OFAS HL / FBP HL dryer includes an electronic control system with colour display, providing a visual indication of
the unit's performance. Linked to this control system is a dewpoint sensor which constantly monitors the outlet dewpoint and adjusts
the regenerating cycle to exactly match the incoming water vapour loading of the dryer.
EST Operation
At the end of the regeneration cycle and prior to column changeover, the exhaust valve is closed to allow the purge air to re-pressurise
the off-line column. After re-pressurisation, both drying chambers will be at full line pressure, no purge air is being used for
regeneration and the dryer is in a state of zero energy consumption.
With a fixed timing cycle, the drying chambers would now proceed to change over automatically, however with EST, the controller
will use the included dewpoint sensor to check the outlet dewpoint of the dryer. If the compressed air dewpoint is lower than the ECO
setpoint (the dewpoint for which the dryer was selected to deliver), the desiccant material is only partially saturated and has drying
capacity remaining within it.
The EST energy saving technology will therefore override the standard timing cycle and the dryer will continue
to dry on the same column with zero energy consumption for regeneration. During this period, “ECO” will be
displayed on the controller screen underneath the outlet dewpoint value.
The dewpoint sensor constantly monitors the outlet pressure dewpoint until the eco setpoint is reached, at which point column
changeover will occur.
The drying and regenerating cycle will then continue normally until the next column changeover when the EST energy saving
technology may again extend the drying cycle as dictated by the outlet pressure dewpoint.
During the extension of the drying cycle, no purge air is consumed, saving compressed air, energy and money.
The diagram below illustrates the EST timing cycle of a CDAS HL / OFAS HL / FBP HL operating at variable inlet conditions (EST
‘ECO’ active, Moisture Override Not Activated).
Important Notes:
Should an error occur with either the Parker Dewpoint Sensor (PDS) or the Dewpoint Hygrometer, a yellow box
will appear around the dewpoint icon. The outlet dewpoint figure will be replaced with “---“and “ERR” will be
displayed.
The dryer will revert to a fixed 3 minute half cycle (3 minutes drying / 2.5 minutes regenerating / 30 seconds
repressurisation) until the sensor is replaced.
1
2 Colum
n
Drying
Repressurisation
Energy Savings Regeneration
Up to 1800
Up to 1800 180 150 1
EST ‘ECO’ Cycle (Moisture Override Not Activated)
ECO Cycle (Drying Cycle Extended M/O Not Activated
0
Drying
Regeneration Repressurisation Energy Savings
Up to 1800 180 150 1
Up to 1800
ECO Cycle (Drying Cycle Extended M/O Not Activated
Seconds