The COPIS (Ko-pes) Megalodon
There
has been much speculation and discussion on this topic for some time, but now
here is the official product release and description of the COPIS (Constant
Oxygen Pressure Injection System) Megalodon CCR.
First
a bit of history:
While
at my ISC Megalodon build course, I made a bit of a mistake and FOD’d a very expensive acetyl Meg head making it unusable
for sale (whoops),
So,
after many hours of hard thinking, research and work, I came up with a way to
make this happen. The key points in my
mind were:
Use
as many off the shelf parts as possible
Keep
it simple!
Keep
it recreational (ISC already has an Apecs MEG,
capable of 600+fsw)
Keep
the price down and affordable for guys like me who don’t have money spilling
out of their pockets
Make
it reliable and robust
Make
sure it’s upgradeable to a full electronic MEG
I
put together the very first unit, over a year and a half ago, using a circuit
board for the displays designed by Mark Munro of PPO2.com fame. He was a big help in cutting down one of his
designs to fit inside the MEG handset. This was an analog circuit that
calibrated by turning small potentiometers on the back of the board, there was
even a small LED near the pot's to illuminate them for doing a cal in darkness,
the only problem was, you had to open the handset to calibrate. We proposed machining a cap in the end of the
handset but that would have added machine time and cost. In the history of the MEG, the only handset
floods that have ever happened were from end users opening up the handsets, so
this violated the reliable and simple rules.
I did dive that unit for 6 months and then passed it on to PattiMegDiver
when she decided she wanted a MEG to dive and she dived that for almost a
year. I just exchanged her electronics
for the new digital version last week.
Close-up of the COPIS
handset and displays.
The
new digital version requires no opening of the handset, period. The new version has 3-3.5 digit backlit panel
meters running off of a small microcontroller that "does the math"
and manages power and backlight functions.
The displays are arranged vertically in the stock MEG handset and use
the same cable, buttons, battery box, and reed switches as the standard MEG
Primary handset.
The Head and handset.
The
way the unit calibrates is as follows.
Say the number one display is reading .216 in air, to enter cal mode,
push both buttons on the handset until the number one (top) display backlight
comes on, then the top button will increment the value by .01 per push, and the
bottom button will decrement the display by .01 per push. Either button will accelerate the change by a
push and hold. To return the errant
display to .209, one would push the bottom button 7 times. To access the second display, press both
buttons simultaneously until the second display backlight comes on and the
first turns off. Proceed as above until all displays are correct. As stated
above, you could also do your cal in pure O2, or any other gas with a known oxygen content.
ISC recommends calibrating in pure O2 and verifying the cal in air, or
vice versa, to provide the diver with a linearity check of the cells.
There
are also a pair of wet sensors on this handset, activating the wet sensors will
lockout the calibration system, and activate backlight controls. During a dive, (wet sensors active) pressing
the top button momentarily will activate the backlights for several seconds, then turn them off.
Pressing the top button and holding until all the decimal points flash
once, will activate the backlights for the duration of the dive. You can turn them off again with another
press and hold. If the backlights will
not activate, this is an indicator that the batteries are low in power and
should be replaced at your soonest convenience.
There is also a low battery indicator on the display and this is a
warning that you would want to change the batteries prior to the next dive. Of course, constant use of the backlights
will shorten battery life.
The
rest of the rebreather is exactly the same as a stock MEG. The counterlungs, ADV,
mixed gas bypass, DSV, breathing hoses, plenum, scrubber options, are all the
same. The beauty of this is, you have a very robust and proven platform, that is customizable and upgradeable, with
excellent flood recovery options and multiple gas sharing paths, but very
simple to dive. The only differences are in the head, the oxygen regulator, and
the hose between the oxygen regulator and the head. It is possible to switch between a COPIS head
and an Apecs head in 5-10 minutes, less if you have
an O2 regulator set up for each.
The
difference in the O2 regulator is the addition of an ambient pressure blocker, that keeps the intermediate pressure of the
regulator fixed, regardless of the ambient pressure. If you are familiar with SCUBA regs, you know
that the IP of a normal reg tracks with depth staying
approximately 135-150 psi above ambient
pressure. With this type of injection
system, if one were to use an unmodified regulator, the O2 flow would increase
as depth increased, providing too much oxygen to the diver ,
a steadily increasing PO2, and risking an O2 tox. This system is only functional to about 300fsw,
or where the ambient pressure equals the intermediate pressure the O2 reg is set to. This
also requires the diver to set the IP (and subsequently the flow rate) to match
his or her VO2, or metabolic oxygen use at rest. There is a small orifice in the hose between
the O2 reg and the head, that
restricts gas flow to about .5-1.5 liters per minute, again depending on what
the IP is set for. We had tried a couple
different places to put the orifice, including in the head after the elbow and
bulkhead fitting, but decided for reliability’s sake to bury it, and a filter,
in the feed hose to protect it from sea water.
Not having it in the head also reduces the possibility of the fitting
leaking and affecting the PO2, now if it leaks, it will be visible (while in
the water) and outside the loop. The
system does not use a separately plumbed valve, like on the Jetsam rebreathers,
just the aforementioned orifice and the stock MEG O2 manual add button on the
right counterlung. The orifice and
manual add button are both plumbed to the same regulator, so at depth, the
manual add button adds less gas per second, the deeper you go. This aids in preventing a spike in PO2 at
depth, where it is most critical. It is
also easy to move the oxygen add to the left counterlung, if injecting into the
inhale CL is a concern to you.
For
those not familiar with this type of injection, this is not a setpoint
controller, it is a manual add CCR, just with a slower decay system that gives
you longer times between manual injection.
The diver is completely responsible for the oxygen content of the loop,
and the setpoint control is located between the divers
ears. The diver should
check loop PO2 every 3-5 minutes and continuously during an active ascent. With a properly set up IP/flow
rate, a diver might only have to use the manual add 2-3 times during a constant
depth dive. Of course, during
ascent, monitoring and adding require more attention.
The
differences in the head are: only one
battery box, and no switch on it, power is applied by
plugging in the cable to the box. This reduces cost and build time.
Battery Box and connector.
The
connector is also a pathway to software upgrade for the microcontroller.
The
head has no solenoid, but uses the same through head fitting and quick connect
as the Apecs.
There
is only one handset, but three independent cells and displays.
This,
of course, will lead to discussions of limited redundancy, but again, this is a
recreational unit, not designed for deep maximum deco diving. If the displays fail, end your dive. If you want a unit to dive deeper and do
exceptional exposure diving, step up to the Apecs Meg
with its dual controllers and two handsets.
With that said, there is a HUD in the works, that will use a second
battery box and other than the sensors, will be a completely separate and
redundant monitoring system. The HUD
will use the same blink pattern as current MEG users are used to and have
aboard some really neat functionality stuff.
Also
on the head will be at least one empty port that can be easily used to feed a
dive computer, such as a VR3, or an HS Explorer, data from one of the oxygen
cells for real time deco. There is no
problem paralleling two monitoring devices on the same cell, but the prudent
diver would always make sure when rotating cells, that the middle cell is on
the dive computer. The reasoning behind
using the middle cell is that it is proven stable, and not the oldest. If one were to replace the oldest cell every
4-5 months, there would always be one new, one in the middle and one old. The
middle one is expected to be the most reliable.
The computer cable and port will be a factory option on the units ISC
builds.
The
COPIS MEG is available to order now, with expected delivery in 60-90 days and
the unit will be available 3 ways. One, as a ready to dive unit with cylinders, regs, hoses, sensors,
BCD, literally ready to dive. Two
as a stripped unit, can, loop, and head only, so you can put whatever cylinders
BCD etc you desire. Third as a kit, with
a few things assembled, such as the handset and sensor carriage that are critical.
ISC is working on a build course, in conjunction with the dive course,
so the units can be assembled under tutelage, whether at the ISC facility, or
on location. Then step right into the
end user course and go diving. We will
have units at DEMA, as well as OZ-tek, to show. There are currently 6 units being dived
regularly, two in Norway, one up in BC, one in Seattle, Patti’s and one in the
hands of Scott Torborg, who is the genius behind the current COPIS electronics
and the new HUD. Pricing of the unit is
to be in the $6,100 range USD.
So,
I am proud as punch to see a major idea of mine get off the ground, its amazing
how long and how much work it took, but the end result is even better than I
had first imagined. Thanks to all who
contributed, Leon, for backing the effort, and the whole staff at ISC,
especially Scott, and Mark Munro, who helped with the first analog board back
when it was just a toy for me, and
Patti, my own little crash test cutie, with a PO2 that never wavers.
Ron
Micjan
5
August 2006