Micra ADJ Second Stage Service & Repair Manual
17
© 1997 U.S. Divers Co., Inc.
NOTE: If leakage persists after performing the above proce-
dures, refer to Table 1, Troubleshooting, and disassemble as
required to remedy the problem.
11. Turn the valve of the air source completely shut, and purge
the second stage to depressurize the system. Disconnect the
in-line adjustment tool from the second stage, and connect the
female fitting of the IP hose to the second stage inlet. Apply a
torque wrench with
n
" crow-foot to tighten the IP hose
fitting to a torque measurement of 40 inch-lbs (
±
3).
NOTE: If an accurately calibrated airflow test bench is not
available, proceed to Subjective Tuning Procedures provided
on the following page.
SECOND STAGE AIR FLOW TEST
1.
With the regulator still connected to the test bench, pressurize
the system to 3000 psi (
±
100) and place the second-stage
mouthpiece over the mouthpiece adapter.
2.
Turn the second stage adjustment knob in clockwise between
2-w
turn, only until the airflow has stopped.
3.
Slowly turn the flowmeter control knob until the flow reaches
a minimum of 15 SCFM (425 liters per minute). The reading
on the Magnahelic gauge (inhalation / exhalation effort gauge)
should indicate no more than +6.O” H
2
O. If the reading
e6.0" H
2
O, refer to refer to Table 1 - Troubleshooting
for corrective guidelines and specific procedures.
SECOND STAGE OPENING EFFORT TEST
1.
With the second stage adjustment knob turned in clockwise
2-w
turn, turn the flowmeter control knob shut, and then
slowly reopen while watching both the Magnahelic gauge and
the intermediate pressure gauge.
2.
When the intermediate pressure gauge begins to drop below
the intermediate pressure “lockup,” the magnahelic gauge
should indicate an opening effort of +.6" of H
2
O to 1.0" of
H
2
O.
3.
Turn the second stage adjustment knob completely in clock-
wise, and repeat the above procedure to ensure that the open-
ing effort does not exceed 2.7" of H
2
O. If the opening effort is
not within these prescribed ranges, refer to Table 1 - Trouble-
shooting.
SECOND STAGE PURGE FLOW TEST
1.
Turn off the flowmeter control knob.
2.
While the second-stage is still mounted on the mouthpiece
adapter, watch the flowmeter gauge and fully depress the
purge cover. The flowmeter gauge must indicate a minimum
of +5.0 SCFM (142 L.P.M.). If the purge flow is less than
+5.0 SCFM, refer to Table 1 - Troubleshooting.
