Bendix Commercial Vehicle Systems AD-9si Oil Coalescing Air Dryer - Manual (Page 6)

6
FIGURE 4 - BENDIX ® AD-9si ™ AIR DRYER WITHOUT GOVERNOR—CHARGE CYCLE
COMPRESSOR
DESICCANT
BED
DELIVERY
CHECK
VALVE
PURGE
VALVE
TURBO
CUT-OFF
VALVE
(OPEN)
CONTROL
PORT
SUPPLY
PORT
FRONT
RESERVOIR
SAFETY
VALVE
REAR
RESERVOIR
PURGE
ORIFICE
OIL
COALESCING
FILTER
CONTROL
LINE
PURGE AIR
EXTENDED
PURGE
PORT
EXHAUST
DELIVERY
PORT
The actual regeneration of the desiccant drying bed begins
as dry air from the purge volume flows through the purge
orifice into the desiccant bed. Pressurized air from the
purge volume expands after passing through the purge
orifice; its pressure lowers and its volume increases. The
flow of dry air through the drying bed regenerates the
desiccant material by removing any water vapor adhering
to it. Approximately 40 seconds are required for the entire
contents of the purge volume of a Bendix ® AD-9si ™ air
dryer to flow through the desiccant drying bed. This time
will increase if the dryer is fitted with an extended purge
reservoir.
The delivery check valve assembly prevents air pressure
in the brake system from returning to the air dryer during
the purge cycle. After the purge cycle is complete, the air
dryer is ready for the next charge cycle to begin.