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KMB 18 & 28 MANUAL
The KMDSI Overpressure relief valve, part
number 200-017, has been manufactured in two
different flow rates. The original valve had a
lower flow rate that the current valve. The current
valve has been marked in two ways, the first
being a groove around the flats of the hex. Cur-
rently the valve is marked with a groove around
the top of the body. These are the same valve, just
different marks.
Shown are the three versions of the over pressure relief
valve
DANGER: Your auxiliary air/gas
supply on a deep mixed-gas dive is ex-
tremely limited. All divers must be aware
of exactly how long their bailout bottle
will last at depth. For example, a diver
breathing one cubic foot of air a minute at
the surface will use a 50 cubic foot bailout
bottle in approximately 7 minutes at 198
FSW while at rest.
1.5.3 Reducing Carbon Dioxide
It is important to reduce the internal volume of the
mask that the diver is breathing through. Carbon
dioxide (CO
) can build up if proper flushing does
2
not occur. A rubber oral nasal mask (9) is located
inside the mask to fit over the diver's nose and
mouth. The oral nasal (9) attaches to the regulator
mount nut (8). This separates the breathing gas
flow from the larger gas space on the interior of
the mask, and this in turn reduces carbon dioxide
buildup.
page 14
© Copyright 1970-2003 Kirby Morgan Dive Systems, Inc. All rights reserved. Document # 010518001
WARNING: Always be sure the oral/
nasal valve is properly mounted in the
oral nasal mask. If the valve is mounted
improperly or absent this can lead to a
higher CO
level inside the mask. A higher
2
CO
level can cause dizziness, nausea,
2
headaches, shortness of breath, or black-
out. This can also increase the probability
of decompression sickness. The correct
flow of gas is from the mask into the oral
nasal.
DANGER: Do not confuse the oral/
nasal valve with the main exhaust valve.
They are not the same thickness. The
main exhaust valve is much thicker. Us-
ing the main exhaust valve in the oral
nasal valve body will restrict the air flow
to the diver. Using the oral nasal valve in
the main exhaust could cause water to
leak into the mask.
1.5.4 Main Exhaust System
The main exhaust system (64,65,66,67) is located
at the bottom of the mask frame (17). Breathing
gas exiting through this valve automatically purges
water from the interior of the mask. This happens
naturally because the valve (66) is the lowest part
of the mask during normal working or swimming
conditions. The cover (65) may be removed by
unscrewing the two screws (64) . Removal of the
cover (65) permits access to the rubber mush-
room valve (66). The main exhaust body (67) on
the KMB 18 is held in place by three screws (69).
(Note: The main exhaust body is molded directly
into the mask frame on the KMB 28.)
The rubber mushroom valve (66) is designed to
present a resistance to the flow of exhaust gasses.
This is necessary to prevent the demand regulator
(63a/b) from turning on a steady flow when the
diaphragm (52) is positioned lower than the main
exhaust (66) during a dive. The diver does not
encounter this resistance as he exhausts out of the
regulator exhaust.
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