Impulse Second Stage Service & Repair Manual
9
© 1997 U.S. Divers Co., Inc.
21. Turn the valve module as needed to align the hex feature with
the hexagonal opening of the box bottom so that the lever
stands straight up inside. Press the valve module completely
into the box bottom, until the adjustment knob is flush against
the outer side.
22. Place the O-ring(22a) over the threaded inlet of the valve
body, so that it rests inside the opening of the box bottom.
23. Place the hexagonal spacer bushing(12) over the threaded inlet
of the valve body, and align it with the hexagonal opening of
the box bottom. Press the bushing completely down over the
valve body to seat the O-ring beneath it.
24. Thread the hex nut(11) clockwise by hand onto the inlet of the
valve body, with the flat side facing in towards the box bottom
and the shoulder facing out. While holding the box bottom
secure, apply a torque wrench with 22mm crow-foot to tighten
the hex nut snug to a torque measurement of 45-55 inch-lb.’s.
25. Turn the adjustment knob out counter-clockwise only until
resistance is felt; to ensure that the knob cannot be completely
unscrewed and removed from the valve body. This will
positively determine whether the retaining pin has been
correctly installed and will effectively hold the adjustment
knob securely in place.
WARNING:
If the adjustment knob can be completely
unscrewed and removed from the valve body, do not attempt
to assemble any further. Disassemble as needed to cor-
rectly install the retaining pin. Severe injury or death may
otherwise result from attempting to use the second stage if
the retaining pin is not correctly installed.
26. Install the diaphragm(5) into the box bottom with its raised
center facing up, and check to ensure it is evenly seated onto
the shoulder at the base of the threads.
27. Install the thrust washer(4) over the diaphragm, and tamp
down to ensure that it seated evenly on all sides.
28. Place the retaining ring inside the open face of the box bottom
with the side that contains four open holes facing up. Without
disturbing the position of the diaphragm or thrust washer, turn
the retaining ring clockwise to engage the threads, and apply
the Circlip/ Retaining Ring Tool to tighten completely snug.
29. Check the secure fit of the diaphragm by grasping the raised
portion of the diaphragm between thumb and forefinger, and
gently moving the diaphragm back and forth, up and down. If
the diaphragm is not securely fastened in place, disassemble
as needed to reinstall the diaphragm, thrust washer, and
retaining ring before performing any further assembly.
30. Fit the purge cover(2) inside the box top(1), and align the box
top over the open face of the box bottom so that the extended
portion is facing 45 degrees below (counter-clockwise to) the
inlet of the second stage (see Fig. 16a). After achieving the
Fig. 16a - Boxtop Installation - Step 1
