Troubleshooting guide

14
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The Charging, Air Treatment and Storage System: Air Dryers
Purge Cycles, Purge Volume
When the air pressure in the supply air tank reaches the
required level, the governor makes the compressor stop
building air and allows the air dryer’s “purge cycle” to
begin. During the purge cycle, the desiccant material is
regenerated (its ability to remove water is renewed) by a
reversal of the saturation process. A small amount of dry
air passes back through the desiccant material and the
water that has been collected, as well as any oil droplets
collected by the oil separator, are purged out through the
base of the dryer. It is normal to see a small amount of
oil around the purge valve.
The Bendix
®
AD-2
®
, AD-9
®
, AD-9si
™
, and AD-IP
®
air
dryers are designed with an internal storage (“purge
volume”) of dry air for the purge cycle.
“Extended Purge” air dryers — such as the Bendix
®
AD-IP EP air dryer — are designed with an extra amount
of air storage internally that is used to assist in the purge
cycle.
Air dryer end covers are typically equipped with an integral
(12- or 24-volt) heating element for winter operation.
Integrated Air Dryer Modules
Technology advances in the charging, treatment and
storage, have resulted in the availability of integrated air
supply systems.
For example, the Bendix
®
Dryer Reservoir Module —
featuring the Bendix
®
AD-IS
®
(Integrated Solution) air
dryer — provides heavy vehicles with integrated purge
and supply reservoirs, an air dryer, governor and a
number of the charging valve components, including four
pressure protection valves.
Bendix
®
EverFlow
®
Modules
Bendix
®
EverFlow
®
air dryer modules are used for air
dryer systems where a vehicle needs a continuous fl ow
of air, such as for bulk unloaders and central tire infl ation.
As stated earlier, air dryers need to initiate a purge cycle
periodically to refresh the moisture-removing desiccant
material. Bendix EverFlow air dryer modules have two
air dryers plumbed in parallel that take turns supplying
air, resulting in a continuous, uninterrupted supply.
Bendix
®
AD-IS
®
Air Dryer
(This example features a Bendix
®
PuraGuard
®
Oil Coalescing Cartridge)
Reservoir
Dryer
Reservoir
Module
Bendix
®
EverFlow
®
Module
Bendix
®
AD-9
®
EverFlow
®
Air Dryer
Assembly
Bendix
®
AD-IP
®
EverFlow
®
Air Dryer Assembly
Bendix
®
AD-IS
®
EverFlow
®
Air Dryer
Assembly