16
Micra ADJ Second Stage Service & Repair Manual
© 1997 U.S. Divers Co., Inc.
5.
Turn the second stage adjustment knob completely out
counter-clockwise, and set the vane adjustment switch to the
"MIN" position (see Fig. 25).
6.
Connect the first stage to a filtered air source of 3,000 psi.
NOTE: The preferred air source for final tuning and testing is
a flow bench with accurately calibrated gauges. If a flow
bench is not available, a scuba cylinder may be used, follow-
ing the subjective breathing test provided on page 16.
7.
Slowly open the valve of the air supply to fully pressurize the
regulator. Press the knob of the inline adjustment tool inward,
and gently turn the knob until it can be felt that the adjustment
stem has mated into the slotted head of the crown. Continue
to hold the knob inward, in order to prevent it from being
pressed outward by the internal air pressure.
a. If airflow cannot be heard, slowly turn the crown out
counter-clockwise only until a very slight leak is present.
b. If strong airflow beyond a slight leak is present, slowly turn
the crown clockwise in very small increments of adjust-
ment while simultaneously depressing the purge of the
second stage, and pause to listen after each adjustment until
only a slight leak remains. It is important to adjust the
crown in this manner only until the airflow has stopped,
without over-adjusting. When only a slight amount of
airflow is present, release the knob of the adjustment tool to
ensure that it no longer makes contact with the crown.
8.
When a slight leak has been established, turn the second stage
adjustment knob between
2-w
turn clockwise. Purge the
second stage, and then listen closely to determine whether any
airflow can still be heard.
a. If airflow can still be heard, re-engage the inline adjustment
tool with the crown as described in step 7, and turn the
crown slightly in clockwise only until the airflow has
stopped. Release the knob of the adjustment tool to ensure
that it no longer makes contact with the crown.
CAUTION: Over-adjustment of the crown will cause exces-
sive spring load in the second stage valve, and will severely
degrade the performance of the regulator.
9.
To test the setting of the crown, turn the second stage adjust-
ment knob completely out counter-clockwise to initiate a
slight flow of air, and then slowly turn it back in clockwise to
verify that the airflow has stopped completely before it has
been turned
2
turn. If more than
2
turn is required to shut
off the airflow, it will be necessary to readjust the crown as
described in step 8a.
10. After turning the adjustment knob
2
turn clockwise to stop
the airflow, purge the second-stage regulator several times and
listen for any leaks. Perform any follow-up adjustments as
needed at the source to eliminate the leakage.
Fig. 25 - V.A.S. & Adjustment Knob Settings
