The rEvo CCR
Paul Raemaekers came
all the way from Belgium to the Dominican Republic in March of 2007 and brought
along a couple of his neat K-CCR units he calls the rEvo. One is a full size unit with 19cf (3 L)
cylinders strapped on, the other is a smaller unit with 13cf (2L)
cylinders. Both units are identical as
far as how they work, just different heights and weights. The mini unit also has a bum plate that
slides out and supports itself on the divers…well, bum, taking the weight off
of the small of your back. This is just
one item in a list of slick design ideas that Paul came up with when he decided
to manufacture his own design of rebreather.
The rEvo is a back mounted counterlung, fully closed circuit
rebreathing SCUBA unit. It can be had in
a couple of configurations, one is as a manual, leaky valve, or kiss style
rebreather, which trickles O2 into the loop and has a manual bypass to push
more oxygen in if needed. There is not
an automatic system controlling the PO2 in the loop, the diver is in charge of
what he/she is breathing. The system is
also available with a Shearwater Research Pursuit with integrated deco, which
is a solenoid operating PO2 control system.
Bruce Partridge (SRI owner) would say the diver is still in charge of
what they are breathing, but the controller does keep a look out on the loop. The manual system uses a fixed orifice to
provide the proper flow based on the divers individual metabolic rate, this
also requires a regulator with a fixed intermediate pressure and rEvo is using Apeks regulators
with a blocker in place on the oxygen reg, to
maintain the fixed IP. A tool is
required to remove the end cap and blocker from the reg
to adjust the IP and hence the O2 flow rate.
On either system, the
diver has the option of adding either diluent or oxygen via two small buttons
that actuate valves and add gas to the loop.
The buttons are situated at the bottom of the unit, recessed into the
housing of the rEvo.
Oxygen injection is on the right side of the unit, and diluent is on the
left, following conventional standards.
On my pool session and subsequent ocean dive on the unit, I found the
buttons easy to reach and activate. I
would like to try this with heavy neoprene gloves or Drysuit gloves on, but
since Paul is no stranger to cold water diving, I expect that this will not be
an issue. The unit also has an ADV or
Automatic diluent valve for adding diluent on descent.
Pics of the manual
inject buttons. The rubber foot helps
find the recessed button. (looking at the bottom of the unit, while it lays on the
front) It actual use it was quite easy
to find and activate.
The casing of the
unit is laser cut and bent, from either stainless or titanium (for weight
savings) and it is finished quite nicely, with all edges clean and dulled. The cylinder attachments are a nifty slide
and lock arrangement and the additional weight of the cylinder mounts are
negligible. The mount slots are actually
part of the main housing of the rig, so no need to bolt something else on
afterward. There is also an auxiliary
attachment point for a battery canister that uses the same technique. The unit is only 64 x 40 x 18 cm which makes
it only as thick as the 3l cylinders that are mounted on it. The weight, fully loaded is 31kg, including
full sorb (2.8kg) SS housing, and 3l cylinders. Empty weight w/o cylinders or sorb is 17.5kg, just right for air travel. The top of the unit also has a small flat area, that is perfect for attaching a 1-2kg trim weight,
designed in, this is another nice little addition that shows how well Paul was
thinking when he put this unit together.
Quick release
cylinder mounts (photo from rEvo manual) I would recommend
some tubular nylon or shrink tube around the hose clamps for corrosion
resistance.
Photo
from the manual, showing the attachment point and bracket for a canister light
battery.
One of the slickest
parts of this unit is the scrubber design.
It consists of 2 separate scrubber canisters, packed individually,
running in series .
The units pack easily and are spring loaded to minimize channeling, and
even if one canister channels, the second one is there to catch the missed
CO2. This arrangement also allows consistent
and complete use of all scrubber material.
The diver packs both canisters at the start of the diving, after 3 hours
of use, the first canister is fully used, pulled,
dumped and refilled. The second canister
is removed and put in the first canisters spot, being only half used, the new
full scrubber is now put in the second spot and the unit is dived two more
hours. This technique prevents the diver
from throwing out ¼ of his scrubber when a single canister is ¾ used. Each canister holds 1.4Kg of material and is
rated for 2 hours, the whole unit is rated for three
hours considering both canisters full.
Of course both canisters are identical to allow them to be swapped. The diver can also order additional canisters
to have ready for a hot swap. This unit
can be recycled to dive again, with proper preparation, in 3-5 minutes.
One
of the rEvo’s two scrubber canisters, notice the coil
spring in the center and the convenient lifting handle. Fine
mesh screen keeps the granules captive.
The loop parts are
from Draeger and are stock on the Ray SCR, the hoses
attach with 90degree P ports to the unit housing, and threaded connectors to the
Ray DSV. This also makes an easy connection
to the Draeger Panorama Mask, with the Draeger P port DSV, no custom parts required. Cleanup is simple, pop the P ports, run water/disinfectant
through the breathing hose, pop the scrubber lid off, pull the scrubbers,
remove the wired in sensor holder and pour water/disinfectant into the two
breathing bags through the scrubber housings, swish around the mixture and pour
out, leave the scrubbers out until the unit is dry.
Draeger Ray breathing loop, with integral weights
to provide neutral buoyancy to the loop. Notice the neck strap that rEvo provides with the unit.
The PO2 monitoring
system is manufactured by rEvo and new to the
market. The rEvo
comes with 2 monitors,
one connected to a single oxygen cell, the other connected to 2 cells and the
display alternates continually between the two readings. Each system has its own internal battery and
a HUD, no external switches or calibration pots. The rEvodream
monitors are programmed, calibrated and set up by activating inertial switches,
basically by bumping them together or with a finger.
Here is a photo of the 2 rEvodream
units, (photo from the rEvo manual) the DSV with HUD
mounts and the attached pressure gauges.
Its obvious that Paul is a sheet metal
engineer, from the high quality things he builds from stainless.
The HUDs have each three tiny LED’s, L2R orange, green and red. In normal operation, at your chosen setpoint
(chosen during the rEvodream setup) you will only get
a single green solid light on each display, this tells you the breathing
mixture is safe. Green=Good. If the loop PO2 goes slightly low, but still
safe, you will get slight pulses of the orange LED and that is an indicator to
inject a small amount of oxygen, to return it to green. The farther below your chosen SP, the faster
the orange LED flickers, but if the green is still on, the gas is still safe to
breathe, just not optimal. The same
effect is seen with the red LED, it will flicker when
the PO2 is over your chosen SP, but become faster the farther away it is. Again, the mix is still safe to breathe if
the green LED is on. Either a flashing
orange minus the green LED (much too low PO2) or flashing red minus the green
(much too high PO2) are indicators that you have a serious problem. I wasn’t sure I liked this method of PO2
monitoring, since I am used to the Smithers Code of
reading the actual PO2, via flashes. In
practice I picked up the sequence easily, but solid lights never give me a warm
fuzzy feeling, I like knowing the software is running and doing something. However, with this system there are two
separate monitors, so for them both to have a software glitch at the same time
would be highly unlikely, the same for losing battery’s. The LED’s are plenty bright and I had no
problem seeing them. The rEvodream modules are expected to run for 250 hours of continuous
use w/o the backlight, and 70 hours with continuous backlight. Backlight is programmable to be on or off in
the setup mode. The units go into sleep
mode after 15 minutes of less than .5 PO2.
This diagram, from
the rEvodream manual, shows the pulses and situations
where you will see the different displays, with chosen SP on 1.25. Of course, if you want exact values, you may
look at the rEvodream main unit, attached to the pressure
gauge.
Underneath the nice
yellow Peanut shaped cover, held on by a spring and wing nut combination, are
the two scrubber housings. Under those
are baskets that hold either sensors, or gas injection parts.
The bottom scrubber
coming out, with the basket that has the gas injection plumbing under it. The gas injection parts,
labeled in red. Notice the color
coded lines, green is oxygen, coming from the O2 regulator, blue is diluent,
coming from that regulator, and white which is coming from the output of the
two manual injection valves on the bottom of the unit. These lines look a bit fragile, but I was
assured that they have bursting pressures well above their use pressure and they
are used in many industrial applications.
The ADV lever, when in place, is activated by the counterlung collapsing
against it. The gas is added to the
exhale counterlung, prior to the exhaled gas entering the first (bottom)
scrubber. There is a one way valve
fitted to the output of the orifice, used to prevent any moisture or
contaminants clogging the orifice from the back side.
The yellow peanut
shaped scrubber lid, and the same lid flipped over.
Notice the gas path between the two scrubbers through the lid. So the
exhaled gas comes from the exhale breathing hose, into the exhale counterlung
down to the basket where the gas is injected, up through the bottom of the
lower scrubber, through the top of the scrubber lid, down into the second
scrubber, where the three sensors are and into the inhale counterlung where it
can enter the inhale breathing hose.
The
basket holding the three sensors. The metal parts and basket seem
to collect any condensation, directing it into the breathing bag, keeping it
off the sensor faces, which is a good thing.
There is an OPV or
over pressure valve fitted to the exhale counterlung and it vents out the back
side of the bottom of the unit. This
could cause premature venting of the loop in an inverted position, but is also
a place to dump any water out that may have entered through the mouthpiece. The valve is similar to a dry suit valve.
The rEvo comes complete with a Backplate, wing and
harness. The Backplate is a spilt design, the top and bottom are at different angles, to allow
the unit to be as close to the divers back as possible. A back mounted CL CCR can dramatically change
the work of breathing by being set off of your back and this helps control that
possibility.
Photo
from the manual showing the split Backplate design. The
bottom plate is adjustable for height to form to the user. Notice the rEvodream
pods fitting nicely over the shoulders and attached to the harness. These were very easy to access during my dive, I never had to fumble to find them. Of course the HUD’s made looking at the
displays a redundant thing anyway.
Loop flow and block
diagram of the rEvo unit. Diagram from the manual.
I spent about 20
minutes with Paul looking over the system and then did about 15 minutes in the
pool getting comfortable on the rig and finding the controls. The hardest thing was learning how to tap the
rEvodream units together at just the correct cadence
to get them to turn on consistently for me.
: ) Honestly this rig is super
simple and would be an excellent unit for the beginning CCR diver, as well as a
smaller lighter unit for the more serious of us. Paul and I set out on a dive with a group of
folks from the event (Pirates cove annual CCR/Wreck week) and we visited three
different wrecks separated by beautiful reefs.
The entire dive was over 2 hours and I had not a moment of trouble from
the rEvo. Its
work of breathing was good, considering the back mounted counterlungs, as good
as a KISS classic and much better than a dolphin. The counterlungs run the whole width of the
housing so the bubble of breathing gas can follow the diver as he/she maneuvers
and changes position in the water. Of
course, swimming inverted is not recommended on a BMCL unit. All in all, I really enjoyed diving the rEvo, if I had room for
more CCR’s in my shed, I would certainly consider one of these. Thanks very much to Paul Raemaekers for
giving me the opportunity to test dive the unit and for putting up with my
silly questions.
Paul diving the shorter model with the bum plate extended.
Quite the trim little
CCR, notice behind Paul’s head, the carrying handle and under it the trim
weight platform
The manual and support
materials are comprehensive and well written.
The course materials and training are being provided by ANDI
international, www.andihq.com
More info at http://www.revo-rebreathers.com/
Ron Micjan
email to: ron (at) tmishop.com