Testing Of Second Stage - Sherwood Scuba maximus SRB5600 Assembly & Maintenance Manual

5.5

TESTING OF SECOND STAGE

A. Inhalation Effort
1. If you have no instrumentation, breathe on the regulator to test the breathing effort. With the
adjusting knob turned fully counter-clockwise a slight hissing free flow should be heard. The
hissing should stop when the knob is turned slightly clockwise. The breathing should be easy
at this point. Turn the knob fully clockwise. The inhalation should be more difficult, but the
purge button should still work.
2. If a water column or water manometer is used to check inhalation effort, it should not exceed
1" w. c. at cracking with the adjustor knob in the minimum effort position. It should drop to
about 3/4" w. c. at one atmosphere and a moderate flow rate. The technician can alter the
inhalation effort within a certain range. The overall inhalation effort can be decreased by turning
the poppet screw
of the range. However, counterclockwise adjusting must stop when the lever
against the lever support
poppet screw
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range. However, clockwise adjusting must stop when air begins to hiss past the second stage
Poppet. Note: This higher effort setting also gives the regulator its greatest resistance to
second stage freeze-ups in cold water diving.
3. Move the venturi adjusting lever
regulator. With surface air flows you will only be able to feel the air moving from a left to right
jetting in the mouth. At greater depths, the volume of air will increase to the point where
adjusting the lever to the "+" position (as indicated on the case) will cause a marked increase in
the venturi effect and subsequent air delivery.
B. Exhalation Effort
1. If you do not use instruments to check the exhalation effort, the flow should feel smooth and
unrestricted.
2. If you use a water column, it should not exceed 1/2" w.c. (.02 bar) at one atmosphere.
3. Brand new exhaust valves will sometimes adhere slightly to the case, causing a slight increase
in inhalation effort. This condition will disappear with use.
C. Leak Test
1. Disconnect the air supply. Purge the regulator of all positive air pressure.
2. Slowly immerse the second stage in a pan of water with the mouthpiece pointing straight up.
3. Immerse the regulator until the water is 1/4" to 1/8" (.64 to .32 cm) from the lip of the
mouthpiece.
4. Hold the regulator in this position for one minute and then slowly raise it out of the water.
5. Tip the regulator mouthpiece downward and watch the inside of the mouthpiece tube. If any
water escapes from the mouthpiece tube, check for source of leakage.
37 counterclockwise, and adjusting the intermediate pressure to the top end
. The overall inhalation effort can be increased by turning the
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clockwise, and adjusting the intermediate pressure to the lower part of the
through its full range of movement while inhaling on the
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18
36 becomes loose