Parker CDAS HL 050 Series, Installation, Operation And Maintenance Instructions, Page: 38 / 75

37
Medium Flow Compressed Air Dryers - IOMI.
OVERVIEW OF OPERATION
CDAS HL / OFAS HL / FBP HL purification systems are based around a heatless adsorption dryer and associated pre filtration and
post filtration.
Adsorption dryers are designed for the treatment of water vapour only and therefore require pre-treatment of the incoming
compressed air to operate correctly and protect the adsorbent desiccant bed. CDAS HL / OFAS HL / FBP HL pre filtration consists
of a general purpose coalescing filter and a high efficiency coalescing filter for the treatment of solid contaminants (atmospheric
particulate, rust, pipe-scale, micro-organisms) and aerosols (oil and water). Should liquid water or liquid oil be present at the inlet of
the CDAS HL / OFAS HL / FBP HL, a liquid separator (OIL-X Grade WS) will also be required to protect the pre filtration.
The heatless adsorption dryer of CDAS HL / OFAS HL
/ FBP HL operates on the Pressure Swing Adsorption
(PSA) principle and consists of two identical drying
columns (referred to as Column 1 & Column 2). Each
column contains cartridges filled with adsorbent
(desiccant) material.
During operation, one column will be used to dry
the incoming process air, whilst the opposite column
is being regenerated and readied for use. Heatless
adsorption dryers use a small proportion of the
dry process air known as purge air to regenerate
the desiccant material. Purge air is expanded to
atmospheric pressure (where it becomes even drier)
and is passed over the off-line desiccant bed where it
strips the moisture from the desiccant material. The
columns will be swapped periodically (referred to as
“changeover”) to ensure a constant supply of dry air is
always available downstream.
Once the compressed air is dried, the air flow path and final treatment differs between CDAS HL / OFAS HL / FBP HL.
CDAS HL
Once dried, the process air is passed through a general purpose dry particulate filter before exiting the unit.
OFAS HL / FBP HL – Column 3
OFAS HL and FBP HL models also include an additional column (referred to as Column 3). After drying, compressed air is passed
through column 3 which contains an activated carbon cartridge for the reduction of oil vapour.
OFAS HL
Upon exiting Column 3, the compressed air is passed through a single general purpose dry particulate filter before exiting the unit.
FBP HL
Upon exiting Column 3, the compressed air is passed through a pair of dry particulate filters (general purpose and high efficiency)
before exiting the unit.
Important Notes:
Different beds of desiccant material are used within each dryer, depending upon the outlet dewpoint required.
Two variants are available to cover three outlet dewpoints of ≤-20°C, ≤-40°C and ≤-70°C.
CDAS HL / OFAS HL / FBP HL
OUTLET DEWPOINT
DESICCANT MATERIAL USED
≤-20°C / ≤-40°C 100% Activated Alumina
≤-70°C
20% Silica Gel / 80% Molecular Sieve
Important Notes:
• CDAS HL / OFAS HL / FBP HL dryer models must be ordered to match the required outlet dewpoint of the site.
• CDAS HL / OFAS HL / FBP HL utilise cartridges that are pre-filled with the correct grade and quantity of desiccant material
(forming the split beds highlighted above).
• CDAS HL / OFAS HL / FBP HL 60 month service kits are therefore specific to the outlet dewpoint of the dryer.