BENDIX TCH-008-040 User Manual
Technical Bulletin
Bulletin No: Effective Date: Cancels: Page: 1 of
Subject:
The Bendix® AD-IP™ & AD-IS® air dryers are available as a standard air dryer and as a DLU discharge line
unloader model. The functions of these air dryers (Standard vs. DLU) and their internal components are
different. The standard air dryer cuts off the supply air from compressor to the air dryer when the compressor
is in the unloaded mode, while the DLU air dryer utilizes a purge valve to bleed off the excess air instead
of unloading the compressor. Externally the standard and DLU versions of each air dryer configuration are
identical in appearance; however the DLU style air dryer often has a silencer on the exhaust port.
The purge valve assembly of the standard air dryer contains three O-rings and the DLU version contains
only two. If a replacement DLU purge valve assembly (2 O-rings) is installed in a standard air dryer the air
inlet to the dryer will not be cut off during the unloaded cycle, but will be exhausted through the bottom of
the dryer. If a replacement standard purge valve assembly (3 O-rings) is installed on a DLU style air dryer,
the air compressor will continue to build pressure in the line between the compressor and air dryer until
the compressor safety valve opens or the purge valve relieves excess pressure. This causes a repeating,
popping sound from the air compressor or air dryer, but may be muffled if an air dryer silencer is installed.
When servicing
air dryer purge valve kits and a side-by-side comparison of the purge valves.
TCH-008-040
5-12-2006
Bendix® AD-IP™ & AD-IS® Purge Valve Maintenance Kits
either air dryer, it is important to use the proper components or kits. Below is a listing of the
3 O-ring
grooves
Purge Valve
Housing
N/A
2 O-ring
grooves
1
Standard
purge valve
Purge Valve Replacement Kits:
Contains a complete purge valve assembly, o-rings,
retaining ring and lubricant.
Pc. No. Comments
Standard Air Dryer - Purge Valve Rep. Kit
800404
5017687 Arctic (low temperature)
5003548 Reman.
DLU Air Dryer- Purge Valve Rep. Kit
5009650 DLU
© 2006 Bendix Commercial Vehicle Systems LLC All rights reserved. 5/2006 Printed in U.S.A.
DLU
purge valve
Purge Valve Maintenance Kits:
Contains all of the components in the purge valve
replacement kit except the purge valve housing. All of the
components are loose and must be assembled using the
existing purge valve housing.
Pc. No. Comments
Standard Air Dryer - Purge Valve Maint. Kit
5003547
5017682 Arctic (low temperature)
Purge Valve O-Ring Kit:
Contains the o-rings, retaining ring and lubricant to service
the standard or DLU style purge valve.
Pc. No. Comments
Standard or DLU Purge Valve O-Ring Kit
5018313
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