Bendix Commercial Vehicle Systems DRM DRYER RESERVOIR MODULE 3/07 - Manual (Page 3)

3
FIGURE 3 - AD-IS ® AIR DRYER PURGE CYCLE.
COMPRESSOR
GOVERNOR
PURGE
CONTROL
CHANNEL
DESICCANT
BED
DELIVERY
CHECK
VALVE
(CLOSED)
PURGE
RESERVOIR
PURGE
VALVE
(OPEN)
TURBO
CUTOFF
VALVE
(CLOSED)
ENGINE
TURBO
OIL
SEPARATOR
PURGE
ORIFICE
PRIMARY
RESERVOIR
SECONDARY
RESERVOIR
GOVERNOR SIGNALS AIR
COMPRESSOR TO SUSPEND
COMPRESSED AIR SUPPLY
TO AD-IS ® AIR DRYER
EXHAUST
PRIMARY
PORT
(PRI)
UNLOADER
PORT
INLET
PORT
(IN)
SAFETY
VALVE
AUXILIARY PORTS
(TO ACCESSORIES)
PURGE
RESERVOIR
DRAIN VALVE
vapor flows through the compressor discharge line to the
inlet (1 IN) port of the air dryer body.
As air travels through the AD-IS ® air dryer, its temperature
falls, causing some of the contaminants to condense and
drop to the bottom of the air dryer purge valve assembly,
ready to be expelled at the next purge cycle. The air then
flows into the desiccant cartridge, where it flows through an
oil separator which removes liquid oil and solid contaminants.
Air then flows into the desiccant drying bed and becomes
progressively drier as water vapor adheres to the desiccant
material in a process known as “ADSORPTION.”
Dry air exits the desiccant cartridge through the center of
the base assembly. The air then flows to the delivery check
valve and also through an orifice into the purge reservoir.
The delivery check valve opens, supplying air to the pressure
protection valves (A) and (B), the safety valve, and also to
the reservoir port of the attached governor. The purge reservoir
fills, storing air that will be used to reactivate the desiccant
during the purge cycle.
When the air pressure reaches approximately 103 p.s.i.,
the first pressure protection valve (A) will open and air will
be supplied to the primary reservoir. When the air pressure
in the primary reservoir reaches approximately 109 p.s.i.,
PRESSURE PROTECTION
VALVES
A
D C B