DCCCR..... what is that? I just got used to OC/DSV-CCR-SCR-PVAR-ADV-MCCR-YBOD-FFM
and even a few more abbreviations.
Now a new one " Diver Controlled Closed Circuit Rebreather". It made me
wonder what was behind that..
I contacted Andy Fritz, managing director of Rebreatherlab in Thailand to
get more information about there new Pelagian rebreather.
It seems I was a bit early asking detailed information, but I am promised to
be informed when the first production is ready!
|Andy wrote down the most questions about his
new rebreather that were asked. When you read the arguments and thoughts he
used in his design, especially the depth compensating first stage together
with a metering valve, it is very interesting!
Q: Why are there so
few detailed pictures on the Rebreather Lab web site?
A: The current web site
was published a few months ago in order to gauge the market interest and a
few pictures were taken to display the streamlined framework and compactness
of the unit.
These pictures are from
one of the prototypes and we wanted to avoid tear down pictures for two
reasons: The production unit will look very different in the head
compartment, (no protruding pipe work and much stronger!), and as we did not
want to confuse people we opted to wait with tear downs until the production
unit was ready. The other reason is that we knew that if people were
interested they would email their questions and we have received loads of
them! As we received a much higher than anticipated interest and sold nearly
all units in the first batch on pre order, we quickly decided to prepare for
higher volume. We built a new larger facility and ordered heavier machinery
which we are now tuning. The first production run is ready in mid January
and we will revamp the web site shortly after.
Q: The O2 delivery system is a
hot topic: Why use a depth compensating 1st stage?
A: Yes I agree it IS a hot topic!
The short answer is to overcome the depth limitation of a non compensating 1st
stage. I have dived a similar system since 97 with very few problems. This
is actually one of the reasons we decided to build the Pelagian in the first
place. The public opinion in the RB community would suggest it is suicide
and I think most people believe they would get twice as high dose of O2 at
10 msw. as on the surface. This is not the case. Think about the difference
in drinking water or milkshake through the same size straw. The denser the
gas the more friction and this slows down the flow. We have done swim tests
with the same needle setting at the surface and then at 40 m and we had to
swim for 10 minutes to pick up any noticeable difference. When I started
diving converted IDA-71’s with this feed system I did not spend much time
with calculations. I just dived and turned down the needle valve a little
when going deeper. Maybe the fact that you do need to stay on top of the
feed keeps you monitoring the displays regularly. Anyway, after some years I
had logged over 700 hours on my IDA, survived the dreaded compensating 1st
stage and thought that it was time to construct an RB from scratch using
this feed system. The needle valve has other benefits like the reduced
chance of clogging and the fact that you take an active part in the O2 feed.
This does not mean that you have to readjust the flow every meter you go
deeper. You typically have one setting for 0 – 30 m and maybe another for
sub 40m. As you get shallower you just puff the manual feed a bit more
often. If you are maintaining constant Po2, you would have to raise the O2
percentage during the ascent on a RB using a non compensating 1st
sage as well. When I dive a Kiss I don’t feel I feed O2 less frequently.
Q: Ok, but what
happens if you go really deep?
A: You turn the needle
all the way down, manually feed and open the needle very little. As a
manufacturer I have to be a bit careful of what I say here, but for the
purpose of theoretical discussion, if some one would worry about the
sensitivity of the needle it would be easy to install a shut off valve and
only feed manually with the over ride button.
Q: Why is the
Pelagian only using two sensors and one display case?
A: Primarily because
there is no solenoid and thus no need for voting logic. Secondly because
many divers want to ad live feed to a VR3 or other computer. There is space
in the head to ad a third sensor that is only feeding the computer. If you
do not want to ad a VR3 you can use either constant Po2 hard tables or
software. Two sensor readings is enough as long as you ensure they are
calibrated, not too old and not current limited. Please bear in mind that it
very easy to validate your Po2 on the Pelagian as the diluent is fed over
the sensor faces. You do not have to purge your loop three times to check
the sensors. All components in the display case are of such good quality
that they would survive a short. A year ago while testing case designs I
flooded the display when I forgot to install the o-ring. The circuit board
got fried on the battery plus side, but all components were ok. After that
we started potting the PCB’s. To test it I deliberately did two dives with a
completely flooded housing and still enjoyed reading the Po2 on both
displays. After the dives I rinsed the electronics in fresh water and dried
it. I still use that display today. I might ad that the case is sealed from
the breathing loop and kept at 1 ATA! You can turn the display on and off
and also turn backlight on and off with only one magnetic switch.
Q: Where is the
battery and what type is used?
A: The battery is a
normal 9V square that you can buy cheap in 7 Eleven. It is kept in the head
in it’s own sealed compartment. This is to address the problems that usually
happen after opening and closing the display to many times and also to keep
the size of the hand unit down. The Pelagian’s display case never have to be
For serious deco dives,
most RB divers prefer to ad an on-line computer. There is already a bulk
head fitting for the cable with a blank plug installed in the head. To
install the computer cable, simply open the fitting, pull out the plug and
run the cable through. If some one would like an additional display instead
of a computer, we sell that as an option.
Q: What is the
scrubber duration, and what method was used to gauge it?
A: We have not done any
CE, or other third party testing. We have simply calculated the weight of
the soda lime, the volume and gas path of the scrubber against typical
metabolism. This gave us a ballpark figure. Then we dived it during 8 months
to much more than the rated duration. On the last dive before a scrubber
change I many times pushed it by swimming really hard for 10 minutes. During
the initial dives I worried about it as I am quite sensitive to CO2 and get
head aches easily, and it was a real boost of confidence when I didn’t get
any. We rate our standard scrubber to 4 hours in cold water and 6 hours in
tropical water. We have a longer optional scrubber mid section that is rated
“up to 8 hours” This means low CO2 and warm water. The durations given by
many other manufacturers are very conservative as unrealistic testing
methods are used. Our figures are based on real dives instead of “in the
worst case scenario” dives. If someone is actually planning on producing 2
liters of CO2 per minute continuously, they should not dive to our rated
durations! Our durations are no mystery. In a standard RB class the
instructor tells his students that RB X scrubber duration is 3 hours. Then
he goes off diving it to 4 hours or more when the student is not watching.
Of course the student picks this up, but he might not know how much the
duration can be exceeded. Our approach is to give him the 4 hours, but
emphasize that this is individual and that caution should be taken towards
the end of the duration.
Q: What is the story
with the curved lungs? What about work of breathing?
A: The curved lungs
come from my personal irritation of having over the shoulder lungs blocking
my chest area. They also follow the body contour, so apart from keeping your
chest cleaner, the W.O.B. is even lower than with standard front mounted
lungs. After all your own lungs are not located outside your body, but
inside. A diver in a standard horizontal swimming position keeps most of the
breathing volume at the same hydrostatic pressure as within his own lungs. I
have received many emails from divers worrying about that a bail out tank
might squeeze the lungs. That is well tested and does not happen. If you
like wearing two slings on the same side and feel a resistance you can
simply move the counter lungs more towards the middle. The lungs come with
two ways of attachment: One that keeps the lungs along the shoulder parts of
the harness. The other is the standard way with a Fastex that clips to the
waist part of the harness. The inner bags are made from vulcanized off road
MC inner tubes. The outer bags are made in Ballistic Nylon. There is an over
pressure relief valve on the exhale side and people can order their units
with it either high or low. When ordering a unit we also ask for body
weight, length and a measure from the top of the shoulder to the belly
button to ensure the right size lungs.
Q: What materials
are used for the other parts? How do you build the Pelagian?
A: We start in a CAD or
3D modeling program to calculate fit and function. Then we cut the parts
with both manual and CNC machines. The scrubber mid section is made from
PVC. Apart from this all other parts are made from black Acetal. The O2 feed
unit is made from brass. The needle valve is user serviceable, but I have
never had to service any. All hoses and fittings are standard. If you break
an O2 feed hose you could use a standard BCD inflator hose as replacement.
If you get a leak in the DSV flapper valve you can cut your own replacement
from a latex dishwashing glove. We use as few o-rings as possible, which is
something I learned from the IDA-71. The whole unit is very easy to set up
and tear down with very few tools and you can service it with many standard
items. In between dives you can get to sensors, battery and water trap with
out pouring the sorb out. There is nothing worse than having to sit out a
dive because you didn’t bring your whole toolbox or enough spare parts!
Q: What is the price
and order procedure?
A: The price for the
standard unit is 5.200 USD. We are running an introduction price for orders
placed before Feb 15 at 4.400 USD. We will produce the Pelagian in batches.
Once we have sold half of the current batch we start producing the next.
This way we hope to keep lead time down, but at the moment it is 60 – 90
days as we have a big back order to deal with. To secure a unit in a batch
we need a 50% deposit, but you can also just ask to be contacted when a unit
is available. A buyer need to have a certification and we provide it at our
facility in Thailand, at the moment through PSAI, but I am sure also through
other agencies in the future. PSAI provide a rebreather friendly system
where you get credit for another CCR certification and only have to complete
the unit specific part of the course. If a diver has no other CCR rating he
will only need an entry level, advanced and basic Nitrox card. We will
incorporate everything else needed in the Pelagian course. The course is
very rigorous and contains many skills beyond what is normally taught in a
standard CCR course. After the course he can take additional levels like air
deco and mixed gas using his RB. He will not have to take the detour of
first getting the ratings with open circuit. We also conduct instructor
courses at our facility and offer incentive schemes to ACTIVE rebreather
instructors who wish to buy units and teach classes. Just ask and you shall
Q: What is included
and how is it delivered?
A: The Pelagian DCCCR
is sold as a kit for liability reasons. We also believe that it you can not
put it together your self, you should not dive it. The standard unit include
mounting plate, 2,7 kg scrubber, O2 display unit for two sensor read outs,
counter lungs, breathing hose with DSV, two 1st stages and O2
feed unit. What you need to ad are O2 sensors, BCD and cylinders. At the
moment we only offer training here which means you have the option to bring
the unit with you or we can send it with DHL, EMS, FEDEX or sea freight. As
more instructors become available we can send through dive centers or
instructors until training is completed.
|Andy, thanks for contributing to my website.
I hope to receive additional information soon.