DUAL DRYER SYSTEM
INSTALLATION/SERVICE
MANUAL (L31279)
®
Outlet Check Valve:
A valve that prevents
downstream air from flowing back through
the air dryer.
Purge Cycle:
The time during which the
air dryer is undergoing decompression and
regeneration.
Purge Tank:
A dedicated external reservoir
for which the air for desorption/regeneration
comes from.
Purge Valve:
A valve or valve unit that
allows the collected moisture and
contamination to be expelled from the air
dryer during the purge cycle.
Regeneration:
The controlled back flow of
air through the desiccant to remove moisture
and contaminants.
Safety Valve:
A valve designed to relieve
system pressure if it reaches a level higher
than normal operating pressures. This
protects other brake system components
from high pressures that could cause system
damage or failure.
Turbo Protection Valve (TPV):
A valve that
closes the dryer inlet during the compressor
unload cycle to avoid engine turbocharge
pressure loss.
Adsorption:
Process by which water and oil
molecules at high pressure are captured by
the desiccant.
Air Dryer:
A device that cools, filters and
dries the air delivered by an air compressor.
Compressor Load Cycle:
The time during
which the air compressor is building air
pressure in an air system.
Compressor Unload Cycle:
The time during
which the air compressor is not building air
pressure in an air system.
Desiccant:
A substance that adsorbs and
desorbs moisture from air.
Desorption:
Opposite to adsorption. When
depressurized in the unloading phase, the air
dryer desiccant will release the water and oil
molecules. At the same time a back flow of
dry air that collects the water and oil is led
through the cartridge and exhausts it via the
Purge Valve to atmosphere. The process is
also called “regeneration”.
Drying Cycle:
The time during which the
air dryer cools, filters and removes moisture
from the air.
Duty Cycle:
Compressor loaded time divided
by engine on time.
Heater:
A heater helps prevent moisture
collected within the air dryer from freezing.
The integrated thermostat on the heater
controls when the heater is energized.
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Glossary
