7
D. A single check valve, or a device with a check valve
feature, may have been installed to the inlet port of
the supply tank or in the delivery line between the
air dryer and the supply tank. This will prevent re-
generation of the air dryer desiccant cartridge and
lead to moisture accumulation in the air reservoirs.
E. Location of the air dryer is too close to the air com-
pressor. Refer to Locating AD-SP
™
Air Dryer On
Vehicle section and Appendix A, Table A, column 2
for discharge line length.
F. In areas where more than a 30 degree range of tem-
perature occurs in one day, small amounts of water
can temporarily accumulate in the air brake system
due to condensation. Under these conditions, the
presence of small amounts of moisture is normal
and should not be considered as an indication that
the dryer is not preforming properly.
Note: A small amount of oil in the system is normal and
should not be considered as a reason to replace the
desiccant cartridge; oil-stained desiccant can function
adequately.
2. Visually check for physical damage to the AD-SP
™
air
dryer such as dented desiccant cartridge, chaffed or
broken air and electrical lines and broken or missing
parts. Check the SC-PR
™
valve also.
3. Check mounting bolts for tightness. Re-torque to 50 ft.
pounds.
4. Perform the Operation & Leakage Tests listed in this
publication.
Every 3600 operating hours, or 100,000 miles or twelve
(12) months:
1. Test the AD-SP
™
air dryer turbo cut-off and purge valves
for leakage. Disconnect the supply, control and delivery
lines from the AD-SP
™
air dryer. Perform the tests below
in the order they are presented.
A. Apply 120 psi shop air pressure to the control port
and a soap solution to the supply port. If leakage
exceeds a 1” bubble in 5 seconds, repair the turbo
cut-off piston and valve before proceeding to step 2.
B. With 120 psi shop air pressure applied to the con-
trol port, apply a soap solution to the purge exhaust
port. If leakage exceeds a 1” bubble in 5 seconds,
repair the purge piston and valve before proceeding
to step 2.
C. With 120 psi shop air pressure applied to the con-
trol and supply port, apply a soap solution to the
purge exhaust port. If leakage exceeds a 1” bubble
in 5 seconds, repair the turbo cut-off piston and valve
before proceeding to step 2.
D. With a plug installed in the delivery port, 0 psi in the
control port, and 120 psi applied to the supply port,
apply a soap solution to the purge exhaust port. If
leakage exceeds a 1” bubble in 5 seconds, repair
the purge piston and valve before proceeding to
step 2.
2. Perform the Operation & Leakage Tests shown in this
publication.
Every 10,800 hours; or 350,000 miles or 36 months:
1. Replace the air dryer desiccant cartridge.
Note: The desiccant change interval may vary from vehicle
to vehicle. Although typical desiccant cartridge life is three
years, many will perform adequately for a longer period of
time. In order to take maximum advantage of desiccant life
and assure that replacement occurs only when necessary,
it is important that Operation & Leakage Tests be performed.
2. Perform the Operation & Leakage Tests shown in this
publication.
WARNING!
This air dryer is intended to remove moisture and other
contaminants normally found in the air brake system.
Do not inject alcohol, anti-freeze, or other de-icing
substances into or upstream of the air dryer. Alcohol
is removed by the dryer, but reduces the effectiveness
of the device to dry air. Use of other substances can
damage the air dryer and may void the warranty.
OPERATION & LEAKAGE TESTS (ALSO SEE
VIDEO BW2327)
1. Check for excessive leakage around the purge valve.
With the compressor in loaded mode (compressing air),
apply a soap solution to the purge valve exhaust port
and observe that leakage does not exceed a 1” bubble
in 5 second. If the leakage exceeds the maximum
specified, service the purge valve assembly.
2. Check for leakage around the desiccant cartridge. With
the compressor in loaded mode (compressing air), apply
a soap solution around the desiccant cartridge seal and
observe that no leakage occurs. If leakage is noted,
tighten the cartridge using a strap wrench and re-test for
leakage.
3. While observing the dash gauge(s), build up system
pressure at approximately 1,800 engine/compressor rpm
to governor cut-out. Note the pressure on the dash
gauge(s) at the moment governor cutout occurs and that
the AD-SP
™
air dryer purges with an audible escape of
air. Observe the dash gauge(s) pressure for two minutes
after the purge cycle begins. The front axle service
(secondary) reservoir pressure should not drop more than
8-14 psi below the governor cutout pressure noted and
the rear axle (primary) reservoir pressure should not drop
more than 2 psi. Perform this test 3 times to positively
confirm the values.
