Bendix Commercial Vehicle Systems AD-9si Oil Coalescing Air Dryer - Manual (Page 4)

4
FIGURE 2 - BENDIX ® AD-9si ™ AIR DRYER WITH GOVERNOR—CHARGE CYCLE
COMPRESSOR
GOVERNOR
DESICCANT
BED
DELIVERY
CHECK
VALVE
PURGE
VALVE
CONTROL
PORT
SUPPLY
PORT
FRONT
RESERVOIR
Note 1:
The Bendix ® AD-9si ™ air dryer purge piston has
a purge control channel drain. This allows any
condensation in this area to flow past a diaphragm
in the top of the purge piston and out through a
channel in the middle of the central bolt of the purge
assembly to be drained. During the purge cycle this
drain is closed.
SAFETY
VALVE
REAR
RESERVOIR
PURGE
ORIFICE
OIL
COALESCING
FILTER
CONTROL
LINE
PURGE AIR
EXTENDED
PURGE
PORT
EXHAUST
EXHAUST
DELIVERY
PORT
CHARGE CYCLE (Refer to Figures 2 and 4)
When the compressor is running loaded (compressing air),
compressed air flows through the compressor discharge
line to the inlet (IN 1) port of the air dryer body. The
compressed air often includes contaminates such as oil,
oil vapor, water and water vapor.
Traveling through the discharge line and into the air dryer,
the temperature of the compressed air falls, causing
some of the contaminants to condense and drop to the
bottom of the air dryer and purge valve assembly. These
contaminants are ready to be expelled at the next purge
cycle. The air then flows through the inlet tube and
into the desiccant cartridge, where it flows through an
oil separator — or coalescing filter if equipped with a
Bendix ® PuraGuard ® oil coalescing cartridge — which
removes water in liquid form as well as liquid oil and solid
contaminants.
Air then flows into the desiccant drying bed and becomes
progressively more dry as water vapor adheres to the
desiccant material in a process known as adsorption.
Dry air exits the desiccant cartridge, through the outlet tube,
then flows to the delivery check valve. Some air exiting
the desiccant cartridge is diverted through the orifice into
the purge volume area. The delivery check valve opens,
supplying air to the two delivery ports. The purge reservoir
fills, storing air that will be used to regenerate the desiccant
during the purge cycle.
The air dryer will remain in the charge cycle until the air
brake system pressure builds to the governor cut-out
setting of approximately 130 psi.
TURBO
CUT-OFF
VALVE
(OPEN)