Valve Adjustment Procedures - Aqua Lung ABS SECOND STAGE Technical Maintenance Manual

ABS Second Stage Technical Maintenance Manual

VALVE ADJUSTMENT PROCEDURES

CAUTION: Prior to adjusting and testing the
second stage regulator, the accompanying
first stage must be correctly serviced, adjusted
to a stable intermediate pressure of 135-140 psi,
and fully tested. Refer to the appropriate first
stage service manual before attempting to
perform the adjustment and testing of the
second stage.
1. Install new o-rings (24, 27) on either end of the MP hose.
Thread the male fitting of the MP hose into the medium
pressure port of the first stage, and apply a torque wrench
with 9/16" crow-foot to tighten to 40 in/lbs (±2).
2. The Aqua Lung inling tool (p/n 100190) can be configured
for a slotted or hex type crown orifice. Pull back the shaft of
the tool to retract the adjusting stem. Insert the threaded inlet
fitting of the ABS valve assembly into the female threaded
end of the tool until snug.
3. Attach the female fitting of the low pressure hose to male
threaded end of the Inline Adjustment Tool until snug.The tool
is shown with the optional inline MP gauge (p/n 111605).
See literature that comes with the tool if additional assistance
is required.
4. Slowly open the valve of the air supply to pressurize the
valve assembly. Engage the stem of the inline adjustment
tool inward, and gently turn the wheel until it can be felt that
the adjustment stem has mated into the slotted head of the
crown.
a. If airflow cannot be heard, slowly turn the crown out
counter-clockwise only until a very slight leak is
present.
b. When a slight leak has been established, slowly turn
the crown clockwise in very small increments of adjust-
ment while lightly depressing the lever to cycle the
regulator. Pause to listen after each adjustment to
determine whether the airflow has stopped. It is
important to adjust only until the airflow has stopped.
c. When the airflow is stopped and no leakage can be
heard after cycling the regulator, proceed to adjust the
crown further clockwise exactly 180 degrees. Then, retract
the stem of the inline adjustment tool to ensure that it no
longer makes contact with the crown.
CAUTION: Over-adjustment of the crown orifice
will cause excessive spring load in the second
stage valve, and may severely degrade the
performance of the regulator.
5. Apply a 1/4" nut driver to turn the locknut clockwise in
very small increments of adjustment; only until the lever
stands just below its maximum height; with a very slight
amount (1–2 millimeters) of freeplay.
Leave 1-2mm of
play in lever
6. Lightly depress the lever several times to cycle the
regulator and listen closely to check for the return of any
leakage, which may indicate that the locknut has been over-
adjusted. If leakage is detected, it is important to return the
crown and locknut to their original preliminary settings, and
then repeat steps 5-6 before proceeding any further.
CAUTION: Over-adjustment of the locknut will retract
the poppet from the crown, resulting in leakage past
the LP seat. Do not attempt to correct this condition
by only readjusting the crown further in clockwise.
Doing so may increase the opening effort and inhala-
tion resistance of the regulator due to excessive
spring load in the second stage valve.
7. When the crown and locknut are properly set with no
leaks and the lever is standing at its correct height, turn the
valve of the air source completely shut, and lightly depress
the lever to depressurize the system. Disconnect the in-line
adjustment tool from the second stage valve assembly.
8. While holding the lever partially depressed, unscrew the
inlet fitting from the valve body and set it aside.
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