Aqua Lung MISTRAL SECOND STAGE Technical Maintenance Manual page 5

Mistral Second Stage Technical Maintenance Manual
NOTE: Aqualung no longer requires
mandatory replacement of the exhaust
valves. As long as the valves and their
associated seating surface are clean and
in good condition, they may be left in place
8. Remove the diaphragm (5) and its sealing ring (4),
then separate the sealing ring from the diaphragm.
9. Using a ¾" (19mm) open end wrench, unscrew the inlet
fi tting (19), then remove the valve body assembly (8-15).
WARNING: The components that make up valve
sub-assembly are under spring tension.
Disassemble according to instructions found in
the next step. Failure to wear proper eye protection
could result in a eye injury should the components
(12-15) eject out of the valve body (11).
10. Stand the valve assembly vertical on the head of the
poppet (14), with the lever (10) facing up, and depress the
valve body (11) to expose the locknut (8). While holding the
valve body fully depressed, apply a ¼" nut driver to remove
the locknut. Next remove the washer (9), and lever (10) and
slowly relax the valve body to lift it off the poppet (14) and
spring (13). Discard the locknut and do not attempt to reuse.
11. Closely inspect the shape and condition of the lever (10)
and the spring (13) to ensure it is not bent, corroded, or other-
wise damaged. If any signs of damage are found, discard the
part and do not reuse.
12. Place the handle of the seat extraction tool (p/n 109437)
directly over the poppet bearing (12) in the top center of the
valve body (11), and press downward until the poppet
bearing has dropped out. Discard the poppet bearing and
do not reuse.
13. Using a needle or sharp pick, stick the center of the LP
seat (15) inside the head of the poppet (14) and lift the seat
out, being very careful to avoid damaging the poppet. Set the
seat aside to be used as an aid during reassembly. Inspect
the head of the poppet to check for any nicks, scratches, or
other signs of damage. The through-hole beneath the LP seat
cavity should be clear and free of any obstructions. If any
signs of damage are found, discard the poppet and do not
attempt to reuse
NOTE: Keep the used seat, it will be of use
during during reassembly.
14. Apply a medium blade screwdriver to the slotted head of
the crown (16) inside the inlet fi tting (19), unscrew the crown
until the threads have disengaged.
NOTE: Because the crown is o-ring sealed,
it will not freely exit the valve body after it has
been disengaged. The following step must
be performed correctly in order to remove
the crown without damaging its delicate
sealing surface.
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