Golem
Rebreathers
has examined
a Respiratory
Minute Volume Keyed (RMV-Keyed)
Passive Semi-Closed Rebreather.
The following is a summary
of
comprehensive report produced
during meticulous dissection
of the unit. Please note that
Golem Rebreathers DOES NOT
manufacture the unit and has
no specific measurements availble
to public. Please contact
Halcyon,
one of the manufacturers of
this type of rebreather for
details.
RMV-Keyed semi-closed
rebreathers attempt to match
injected gas volume to the
divers metabolic consumption
by venting a portion of
the loop volume on each
breath. Fresh gas is injected
by valves keyed mechanically
to the divers breathing
rate in order to keep breathing
loop volume constant.
The use of nested counter-lungs
keeps a constant
volume ratio between
total loop volume and expelled
gas volume and helps to
keep FO2 variations between
2-8%.
Functional Drawing
The drawing on
the right illustrates basic
operation of the RMV-Keyed SCR:
The exhaled breath passes
through the pipe in the
center of the scrubber into
both counter-lungs. Any
water that would enter the
exhale hose is routed directly
into the exhaust counter-lung.
Also, the water trap beneath
the scrubber directs any
condensation into the exhaust
counter lung.
At the end of the exhale
cycle both counter-lungs.
are fully extended. A one
way valve on top of exhaust
CL closes at the beginning
of the inhale cycle. The
gas is driven from the main
counter-lung. through the
plenum into a scrubber and
then into inhale hose.
A valve at the bottom
of the exhale CL opens and
contents of the exhale CL
(and any water routed here)
is expelled out from the
loop.
When the gas volume in
both counter-lungs is
small
enough, the bottom CL plate
will depress two rods
protruding
through the top of the
counter-lung. space. The
rods will activate
add valves that will inject
fresh gas into the plenum.
The cycle repeats.
Tear-Down
On the right is a complete
unit without breathing hoses
and DSV.
On top are inhale (green)
and exhale (red) ports -
hose attachments
Below is an axial scrubber
(gray)
The water trap, plenum
and Add Valve ports are
in the middle of the unit
Bottom perforated part
houses the counter lungs.
The entire unit is held
together by two SS clamps
between the top lid and
CL housing
The blue caps cover standard
second stage thread of the
add valves. each of the
add valves is connected
to one of the two regular
first stages attached to
manifolded twin tanks of
desired size (from AL30
cu ft to Steel 125s)
The orifice between inhale
and exhale ports is a O2
sensor port. It is piped
to the top of the scrubber,
away from inhale hose condensation.
This
is a bottom side of the
scrubber lid (click
on image for larger view).
The exhale hose is routed
into a white pipe in the
middle, the inhale hose
opening is directly above
the hose. The O2 sensor
port opening is to the right
of center.
)
)
