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View Full Version : Don't Ever Do Discovery Rebreather!!!!



CWSWine
08-17-2009, 19:12
Because you will be hooked!!! Myself and couple other forum members had a chance to try out a just released semi enclosed rebreather that does not require any kind of electronics or computers to operate. This rebreather with the small canister has a very conservative bottom time of 4.5 hours and the large one I believe was over 6 hours of bottom time. It breathers a little harder than a high performance regulator but since it only use 25% compressed air it is warmer and slightly moist air.




http://forum.scubatoys.com/gallery/files/5/6/2/8/rebreather.jpg

Scuba Pete
08-17-2009, 20:06
That looks like a rb80 or a GEM. Could you tell us what model that is?

navyhmc
08-17-2009, 20:22
looks good on you Dennis. What brand is it?

CWSWine
08-17-2009, 20:37
looks good on you Dennis. What brand is it?

I don't know if there is a brand name on it yet, they are just getting ready to release it for sale to the public. Its going to be in the 2000.00 range when released and that includes training.

maverick
08-17-2009, 21:04
I got 2 try one out myself.

in_cavediver
08-17-2009, 21:19
I agree - never try them. I have a place in my stable for a nice little CCR. I just need the money for 2 of them now.......

Flatliner
08-17-2009, 21:45
I was on the outside of the pool when the pic was taken. I agree, VERY cool. Plus, I get to tell my buddy who didn't come that I tried a rebreather, na na na na boo boo!

CWSWine
08-17-2009, 22:06
I was on the outside of the pool when the pic was taken. I agree, VERY cool. Plus, I get to tell my buddy who didn't come that I tried a rebreather, na na na na boo boo!


And here is proof....

http://forum.scubatoys.com/gallery/files/5/6/2/8/rebeather2.jpg

Flatliner
08-18-2009, 06:07
Thanks for posting the pic Dennis, Can I get a full size copy of it?

TommyB
08-18-2009, 11:59
That looks like a rb80 or a GEM. Could you tell us what model that is?

From Poseidon Diving System United Kingdom - The Ultimate Dive (http://www.poseidon-uk.co.uk/)



The diving is simple. Open the tank valves, wet the switch on the back of the display, wait for the systems check and off you go. Forget about everything you ever heard about PO2, scrubber life and oxygen cells. Our system will handle all that. Just remember to breathe. You will inhale warm and humid air with a gas mixture optimized for the depth you are at. You will stay warm longer, you will dehydrate less and your body will experience less decompression stress.

You need four consumables for your diving. Oxygen, the pre packed canister, air and a charged battery. Your dealer can cater for all except for the battery which you can charge at home before diving. The cost per diving hour is no higher than for ordinary scuba diving but the added experience is priceless.


Bubble-free Poseidon

No-one knows what future dive-gear will look like, but Poseidon is sure it will leave no bubbles. Its closed-circuit rebreather the Discovery VI is the breathing gear the Swedish manufacturer hopes will revolutionise diving.
Martin Örnroth reports, with additional images from Jesper Kjøller and Poseidon

IN THE 1990S, Audi developed a new small car model. It took a bold step in deciding to bolt the bonnet shut. It concluded that today's car engines were too complicated for the owner to fiddle about with, and that there was little the driver could or should do.
So the A2 model was built with an openable front grille, so that the driver could check engine oil and brake and cooler fluid, and refill the screenwash. That's it. The A2 was for those who wished to focus on driving - and nothing else.
Jonas Brandt and his crew in Poseidon's R&D department followed similar principles when they developed their new rebreather. Discovery VI is a fully closed, fully automatic rebreather for sports divers who want to go to a maximum of 40m without decompression. The number of procedures to be performed by the diver has been minimised - to decrease the risk of "human error".
Poseidon believes that the typical Discovery diver will be a middle-aged gentleman who has been diving for some time and wants to "spice up"
his diving, but is not interested in submersing himself into technical diving, great depths and prolonged decompressions.
Poseidon also wanted to design a breathing "machine" that could be handled by someone who had never even tried diving before. As long as the Discovery functions normally, the user should feel no need to pay more attention to it than he would to the pressure gauge with open-circuit scuba gear. An experienced diver should need to spend no more than 15 minutes assembling his Discovery, and preparing it for the dive.

CONTROL FREAKS
A closed-circuit rebreather is an advanced and complicated piece of equipment. Up to now the intended customer base has been relaxed about fiddling with settings, preparations and pre-dive tests. So how do you design a rebreather for those who are less relaxed?
According to Poseidon, the solution is called "Pre Dive". The Discovery VI needs slightly more than two minutes to pass a self-test of approximately 30 items before you are allowed to start the dive. The test includes leak checks, oxygen sensors, gas pressure, battery condition, software and so on. Unless everything is OK, the message will be "Stop".
We encountered this ourselves before we could splash into the Poseidon pool on our try-out dive. The Discovery needed three test runs before it was entirely satisfied with the set-up. Among other things, one of the O-rings in the gas loop turned out to have a tiny leak.
To minimise the risk of errors in refilling and packing of the scrubber, Discovery is supplied with ready-to-use scrubber canisters that last for three to six hours. The price of a scrubber canister is about £21. Add to this the cost of refilling the gas supply, and you have a running cost of around £8 per hour.
"We were pleasantly surprised when some interesting and unexpected customer groups started making requests. We didn't have those in mind when we developed the Discovery - military units and rescue services. They have shown a keen interest in our 'plug and play' concept," says Jens Sjöblom, Poseidon's Sales Manager.
The Discovery has a unique design, in that it has only two oxygen sensors, but these are subject to constant recalibration while it is in use.
This is done using micro-valves that blow minute amounts of pure oxygen and air alternately across the face of the cells, so giving two calibration points. It was a system originally conceived by cave-diving veteran Bill Stone, the inventor and designer of the original and very complex CIS-Lunar rebreather.
Initially it had been intended that the Discovery would have a single sensor, so reliable was this concept thought to be. Market research since proved to Poseidon that the diving public had yet to be convinced that a solitary cell would be
up to the job, and a second cell was therefore added to the design.

TEST DIVE
Finally it was time for the test dive. I spent a few minutes at the surface, breathing from the system in open-circuit mode. Then I turned the knob on the mouthpiece to closed-circuit. I emptied my BC in the usual way and descended slowly.
At this point, any similarity with procedures from my previous 17 years of diving ended. I had always used my BC to make rough buoyancy adjustments, and the volume of my lungs to make the fine buoyancy adjustments. That doesn't work with a rebreather. The volume of my lungs plus the volume of the counterlung (breathing bag) remains constant during every breath.
I experienced some very instructive minutes in "beginner's mode" before I found my correct balance and buoyancy. Then I could focus on what it was like to dive closed-circuit.
The first thing to strike me was the silence. It was deafening! I was used to a steady stream of bubbles rushing past my mask and ears, and my first reaction was a feeling that something was wrong.
My next impression of the Discovery was its lightness. I could feel no difference in weight or bulkiness between the unit and an open-circuit system, and it fitted well, practically inviting me to perform acrobatic exercises. Hovering a couple of inches above the pool floor was easy.
Before kitting up, I had been sure that the mouthpiece would feel heavy. It is quite a bulky piece of gear to hold clenched between the teeth, but during our brief test dive I felt no symptoms of jaw fatigue.

EDUCATION
On the Discovery, most of the complicated decisions are managed by the dive computer. Nevertheless, there are many routines with which divers have to be well acquainted before they can use a rebreather correctly.
This is why you have to pass a special course before you are allowed to use the Discovery on your own.
For those without previous diving experience, the course lasts for 4-5 days, while for experienced divers, it's a bit less. Poseidon is producing educational materials for TDI and IANTD and others, and has around 40 instructor-trainers and more than 50 instructors lined up to take on students. "Discovery will be in full production very soon, and I don't expect this to be a bottleneck for our expansion," says Jens Sjöblom.
To keep your Discovery active, you have to submit it for inspection and service of the first and second stages every two years.
The dive computer keeps tabs on the interval, and if you neglect or forget the service, the Discovery will refuse to dive with you.


ON THE MONEY
The work on the new rebreather started in 2006, since when some 60 more or less functional prototypes have been tested. Initially, Poseidon built a rebreather for pure oxygen without electronics, just to carry out mechanical tests and check comfort. It also spent some time developing the mouthpiece.
"That was one item we identified as difficult very early on," says Jonas Brandt, Technical Manager and head of the Discovery project "We intended to design something that no one had made before."
The company wanted a mouthpiece that would perform well in closed-circuit mode but would also meet the requirements of EN-250 in open-circuit mode. The resulting unit boasts better breathing-resistance performance than a separate Xstream unit, according to Poseidon.
The company has spent around £2.3 million on developing the Discovery. Only one part of the rebreather is standard-issue "off the shelf" - the first stage. The rest has been developed along the way, with parts including the electronics produced around Sweden, and final assembly is done at the Poseidon factory in Gothenburg.
The first drafts for the design and performance of the new rebreather were outlined long ago. Cost specifications and a projected price level for the final product had already been calculated at that stage, and Brandt concedes that the original calculated cost was exceeded by 5-10%.
With production not yet running at full speed, today the customer has to pay around £4700.
Poseidon professes to be unconcerned that the price tag could deter buyers. With gas bottles, regulators and a fully fledged dive computer included in the price, and the possibility of doing extended dives of up to three hours, it feels that the customer is getting a good deal.
Discovery VI will be available from Poseidon Premium Dealers only. The company estimates that there are 15 million divers worldwide, of whom 10 million are active. If just 1% of these could be persuaded to dive closed-circuit, the manufacturer would be kept busy for a long time to come.
With present capacity, Poseidon can churn out 2000 units a year, but as this is a new and complicated product, it has decided to start with an initial production run of 400.

TWO SENSORS
One of the more controversial design solutions was to provide the rebreather with two oxygen sensors, rather than the three that have almost become standard among other manufacturers.
"We decided very early during the design process to reduce the number of oxygen sensors," says Jonas Brandt. "We actually discussed using a single sensor only, but we didn't think the market was ready to accept that, so we finally agreed on two.
"This is how we reasoned: just because you have three sensors, there is no reason to believe that two are always good and one is bad. It may very well be two bad ones, and only one is good."

INTRODUCTION DELAYED
In the autumn of 2007, Poseidon announced that the rebreather was ready to be introduced. So what happened?
"For six months, we focused entirely on figuring out how the sensors behave," says Brandt. "Consequently, today we know things about the sensors of which even their manufacturers are totally unaware. We have tested them in hot saunas as well as in deep-freezes, only to collect data on how they react under various conditions.
"A lot of this project is about calibration and validation. We don't want to end up in a situation where 300 customers all over the world are unable to use their rebreathers, just because sensor readings are pointing in different directions."
The launch was delayed for a year, which allowed Poseidon to test and fine-tune its new product further. And the market has matured. Poseidon monitored the arguments on international dive forums, on which many of the more conservative posters discarded the whole project as a fiasco.
The Discovery may be a rebreather with a lot of unorthodox and innovative solutions, but general opinion today seems to have turned around.
"We carried out meticulous research when we started working on the rebreather," Jens Sjöblom tells us. "We wanted to establish the facts behind many of the 'truths' that were flourishing.
"Certainly, sport divers are a traditionalist bunch. In many aspects, the rebreather community is even more so. Further, lots of rumours abound. Some are plainly wrong, and a few are utterly dangerous."
Poseidon is the only manufacturer offering a closed-circuit rebreather specially developed for recreational diving, but it says it doesn't mind if others join in and develop their own models.
The more brands trying to reach the market, the more attention will be generated around CCR, and this, it believes, will be to everybody's benefit.

TRAVELLING COMPANION
Many divers with a new Discovery VI would surely love to take it on their next diving holiday. It comes in a hard-shell transport case with foam plastic inside, intended to fully protect it at airports.
However, one fact makes extensive air travel problematic - the unit's 18kg weight, on top of the rest of your dive gear and personal items.
You can remove the two cylinders and
scrubber canister, reducing the weight to a measly 8kg, and Poseidon reckons many customers will take this route. For this reason, it has put a lot of effort into signing up dive centres and liveaboards around the world to provide gas tanks, scrubber containers and spare parts.
The "paint is still wet" on the first Discovery VI units, but plans are already advanced to develop a trimix model for diving to 60m. Poseidon says that it needs only to adjust the computer software.
Nothing has yet been decided about when the trimix version will be released. For those who don't think 60m is deep enough, a third-party enterprise is working on hardware and software for depths of 100 and perhaps even 300m.

we heard reports that the Discovery VI had just won its CE mark! Poseidon Diving Systems, Poseidon Diving System United Kingdom - The Ultimate Dive (http://www.poseidon-uk.co.uk)

mike_s
08-18-2009, 12:07
I was on the outside of the pool when the pic was taken. I agree, VERY cool. Plus, I get to tell my buddy who didn't come that I tried a rebreather, na na na na boo boo!


And here is proof....

http://forum.scubatoys.com/gallery/files/5/6/2/8/rebeather2.jpg


did you get any "rear pics" of the rebreather?

l'm no rebreather expert, but most of the ones I've seen have smaller tanks and larger rebreather components. what's different about this one?

what gas mixture was in the tank also?

TommyB
08-18-2009, 12:37
did you get any "rear pics" of the rebreather?

l'm no rebreather expert, but most of the ones I've seen have smaller tanks and larger rebreather components. what's different about this one?

what gas mixture was in the tank also?


Details on the Discovery Unit
Watch the Movie
http://www.poseidon.com/movies/MKVI.wmv

mm_dm
08-18-2009, 13:58
Details on the Discovery Unit
Watch the Movie
http://www.poseidon.com/movies/MKVI.wmv


Thanks for posting, Tommy- that was simply amazing.

-Mike

CWSWine
08-18-2009, 14:03
I was on the outside of the pool when the pic was taken. I agree, VERY cool. Plus, I get to tell my buddy who didn't come that I tried a rebreather, na na na na boo boo!


And here is proof....




did you get any "rear pics" of the rebreather?

l'm no rebreather expert, but most of the ones I've seen have smaller tanks and larger rebreather components. what's different about this one?

what gas mixture was in the tank also?


Here is a picture of the unit not mounted. It mounts to the cam straps and hook to the tank via a drysuit hose. Your regulator and octo stay attached and are usable during the dive. The tank is filled with standard 32 Nitrox. This one here is set for 75% recovered and 25% dumped. Hooks to any standard BC with dual tank straps. This unit is 100% mechanical there is no computer nor batteries in this unit.




http://forum.scubatoys.com/gallery/files/5/6/2/8/rebreathertank.jpg

scubaman450
08-18-2009, 14:29
we do live in amazing times don't we.

skdvr
08-18-2009, 15:12
Tommy are you saying that the RB in the Pics from the OP is a Poseidon MKVI?

Phil

CompuDude
08-18-2009, 15:48
Very interesting. I'll have to look more into this new RB.

navyhmc
08-18-2009, 15:48
Tommy are you saying that the RB in the Pics from the OP is a Poseidon MKVI?

Phil

It's not the Poseidon MKVI. I've heard that Dive Rite was working on a new RB for rec use, is this it???

mike_s
08-18-2009, 17:14
I was on the outside of the pool when the pic was taken. I agree, VERY cool. Plus, I get to tell my buddy who didn't come that I tried a rebreather, na na na na boo boo!


And here is proof....




did you get any "rear pics" of the rebreather?

l'm no rebreather expert, but most of the ones I've seen have smaller tanks and larger rebreather components. what's different about this one?

what gas mixture was in the tank also?


Here is a picture of the unit not mounted. It mounts to the cam straps and hook to the tank via a drysuit hose. Your regulator and octo stay attached and are usable during the dive. The tank is filled with standard 32 Nitrox. This one here is set for 75% recovered and 25% dumped. Hooks to any standard BC with dual tank straps. This unit is 100% mechanical there is no computer nor batteries in this unit.




http://forum.scubatoys.com/gallery/files/5/6/2/8/rebreathertank.jpg


interesting.

if no computers, how do you set/change it to/from 75% recovered for example? (or to another setting)?

CWSWine
08-18-2009, 17:32
I was on the outside of the pool when the pic was taken. I agree, VERY cool. Plus, I get to tell my buddy who didn't come that I tried a rebreather, na na na na boo boo!


And here is proof....




did you get any "rear pics" of the rebreather?

l'm no rebreather expert, but most of the ones I've seen have smaller tanks and larger rebreather components. what's different about this one?

what gas mixture was in the tank also?


Here is a picture of the unit not mounted. It mounts to the cam straps and hook to the tank via a drysuit hose. Your regulator and octo stay attached and are usable during the dive. The tank is filled with standard 32 Nitrox. This one here is set for 75% recovered and 25% dumped. Hooks to any standard BC with dual tank straps. This unit is 100% mechanical there is no computer nor batteries in this unit.







interesting.

if no computers, how do you set/change it to/from 75% recovered for example? (or to another setting)?

I know very little about rebreathers so tech questions I can not answer but I do know that going below 25%/75% was not recommended for rec diving. You change percentage by changing the mouth piece, they do have mouth pieces that go down as low as 10%. I would have to learn a lot more about rebreathers before I would take below pool depths.

navyhmc
08-18-2009, 17:46
So who made it Dennis??????

skdvr
08-18-2009, 17:59
So who made it Dennis??????

Come on Dennis who came out to the pool to let you dive their new breather???

It looks kind of interesting I would like to be able to read some more about it....

Phil

CWSWine
08-18-2009, 18:38
Here you go guys - this is a link to more info.

Rebreather - Beaver Divers (http://beaverdivers.ning.com/forum/topics/rebreather-1)

maverick
08-18-2009, 18:50
What is the weight of this unit?

CWSWine
08-18-2009, 18:59
What is the weight of this unit?

I would guess about 8lbs.

navyhmc
08-18-2009, 19:05
I couldn't find any websites that home page the rebreather (GEM V6 re-breather/Gas extender)

From the link:

Welcome to sane and safer re-breather diving! The GEM V6 re-breather is the culmination of years of research, design and test diving with emphasis on simplicity, versatility and safety. In fact, there’s been a lot of effort and thought put into making this system simple. This manual will first show you how the GEM is different than all other re-breathers then thoroughly explain operating principals and parameters while moving you toward an understanding of how to dive with the re-breather. This manual is only a guide to learning. You must take the manufacturer's certification course in order to use the GEM safely.
The GEM - A Gas Extender
Think of the GEM as an extension device of your available gas supply. Imagine a single 80 cubic foot tank with the help of the GEM can give you 4 to 8 hours of bottom time!

Semi closed circuit re-breathers add breathing mixture continuously and waste gas in the process. The valves can become inaccurate or dirty giving you too little or too much gas. Fully closed re-breathers try to control use of gas by separating components of your breathing mixture and mixing them on the fly with the sophisticated use of electronics - sometimes with disastrous results. The GEM is a completely different approach using the exhale exhaust / demand addition concept.




As you exhale, the mouthpiece automatically exhausts up to 25% of your exhalation. The rest of the gas continues through the counter lung to the scrubber where most CO2 is removed. As the gas travels to the inhalation lung the system equalizes pressure by activating an automatic demand valve that restores the volume of the lung with fresh gas. The GEM operates on sound physical responses both in your body and in the environment. Therefore, the GEM does not waste gas and valves do not become clogged like a continuous adding re-breather. Unlike closed circuit re-breathers it does not rely on finicky electronics which can be plagued by bad sensors, dead batteries or solenoid valves that can malfunction either slamming shut or open permanently, usually at the worst time. Simplicity IS safety!
The GEM has several other advantages that should enable you to experience instant and very apparent awareness of any system failure. If the demand valve fails to work the system becomes slowly more difficult to breathe and you have several breath cycles to bail out to the integrated open circuit system or add gas to the loop manually. Both with exactly the same depth appropriate gas mix. If the demand valve free flows you can recognize it and take action. You will be immediately aware if the system is not exhausting gas because you monitor it yourself - by watching for a small stream of bubbles. There is no chance of oxygen toxicity if you dive within the parameters of the system, your gas mixes and follow the rules. The GEM has been designed so that scrubber “caustic cocktail” is unlikely . The system is completely redundant. At any time you have at least two fully independent breathing systems.
In addition to these features you have the ability to change gas mixtures as many times as you want any time during the dive. The GEM allows you to decompress on ANY oxygen mix up to and including 100%. Rig your system any way you want - it can be rigged back mount, single or double tank, side mount, you can carry stage bottles and if you really have a need the GEM can be set up for no mount! It’s all about simplicity, safety and versatility.

An Introduction to the System
The GEM is an integrated system composed of a few simple parts: the exhausting mouthpiece, large diameter breathing hoses, two liter exhaust and inhale counter lungs, a large capacity scrubber vessel, and the automatic demand valve. All parts of the re-breather are easy to disassemble for service or cleaning. Let’s take a look at the individual components.

Unlike other re-breather systems and because of the proprietary design of the GEM mouthpiece, it can be used in any swimming position. Unique magnetic valves control the exhaust rate of the mouthpiece from 10 to 25% of every exhalation. Each mouthpiece is set for a certain exhaust ratio (from 3:1 to 6:1) at the factory. For training, open water and non-technical diving mouthpieces are supplied that have a ratio of 3:1, exhausting about 25% of each exhalation. This insures a good gas extension effect while adding more safety to the system. Technical divers who have taken the technical GEM Re-breather course will be able to purchase mouthpieces that have a ratio of up to 6:1 with exhaust rates as low as 10%, drastically increasing the gas extension effect. The mouthpiece also features an integrated on-off valve so you can completely close the unit when it is not in use. *** address where to stow the re-breather hoses when not in use

The breathing hoses are flexible high flow corrugated tubes with integrated weights to suit the individual diver. The hoses help ensure that breathing effort is kept to a minimum.

The two counter lungs are mounted over each shoulder so breathing is not affected by pressure differentials and is much more natural. They are constructed of heavy-duty ballistic Cordura nylon and are easily mounted to any harness system.

The scrubber vessel houses five pounds of the scrubber material of your choice and is an efficient center tube design to reduce “channeling“. The scrubber housing is made of heavy duty clear cast acrylic making it easy to view water intrusion or scrubber color change.
The automatic demand valve is machined into plumbing at the top of the exhalation counter lung and features a quick connect inlet from the available gas supply. The quick connection allows you to plug in any gas mixture.

The basic GEM comes complete with all the items listed above so that you can build the system that is right for you with your selection of BCD/Wings, harness, first stage regulators (at least two are needed) and weight systems. You can add other options such as an O2 monitor, manual addition valve, integrated weight system or water dump valve at any time.


A Few Hard and Fast Rules (that should always be followed)
1. Shallow dives (1 ata or less) must be done with at least NOAA Nitrox Mix #1 or 32% enriched air. NO AIR DIVING ABOVE 33’!
2. You must be trained in Enriched Air to use the GEM. For
the technical program you must be trained in Advanced Nitrox.
3. All ascents must be made slowly.
4. Flush the loop every 15 feet of ascent.
5. Dives WILL NOT exceed the Maximum Operating Depth (MOD) of the gas
supply used.
6. The re-breather loop must NOT be used on the surface.
7. Always do at least a 5-minute safety stop at 15 feet and start the safety stop by flushing the loop.
8. Keep a log of time used on the scrubber material and never exceed it‘s
exhaustion time.
9. Notice problems. If you detect any problem before, during or after diving
the GEM - take care of the problem immediately!
If you always follow these simple rules, chances are you will live long enough to enjoy the GEM Re-breather for thousands of hours. Lets go through each rule and see why they’re important.





Rule #1 - Shallow dives (1 ata or less) must be done with at least NOAA Nitrox Mix 1 or 32% enriched air. NO AIR DIVING ABOVE 33’!
We might add no hypoxic mixes above 1 ata either. As you use the re-breather on an air above 1 ata, the system is supplied with only 21% oxygen. As you breathe you exhaust up to 25% of that volume air and your body uses about 16% of the available Oxygen in the remaining volume. The GEM through it’s automatic demand valve makes up for the loss of volume but only replaces a tiny bit of the 16% deficit of oxygen in the loop because it is supplied with an air or a 21% mix. After a few breaths the gas in the loop becomes too hypoxic to sustain brain function leading to unconsciousness.
Below 1ata (33 feet seawater) air can be used because the increased ppO2 in the air mix (due to pressure) does not let the loop fall to hypoxic levels. The same is true when using NOAA Nitrox #1 (32% oxygen) above 1ata. The increased oxygen in the mix does not let the loop fall below 21% O2 into the hypoxic range.

Rule 2 - You must be trained in Enriched Air to use the GEM. For
the technical program you must be trained in Advanced Nitrox.
It’s simple, for even open water recreational diving with the GEM you must have a clear understanding of Nitrox theory and practice. You must be able to calculate your Maximum Operating Depth (MOD), Equivalent Air Depth, and understand the effects of Oxygen Toxicity and how different gas mixes will effect decompression.


Rule 3 - All ascents must be made slowly.
Remember “shallow water black out” from your open water certification course? Re-breathers can cause the same problem. If you are at depth and make a quick ascent the partial pressure of the gas in the loop can drop dangerously low and becoming hypoxic before the automatic demand valve can catch up. Here’s how it works: as you start your fast ascent on let’s say a 32% mix, depending on depth the ppO2 in the loop will be hovering around 22%. Remember, you are exhausting up to 25% of every breath and only adding that much back to the loop each breath. In addition, the volume of air is expanding in the loop because you are ascending to lower ambient pressure. Because of the decreasing water pressure the partial pressure of the gas in your loop decreases. The remedy for this situation is very simple, slow your ascent to no more than 30 feet per minute and/or flush the loop every 15 feet or every other breath. Ah....that leads us to our next rule...

Rule 4 - Flush the loop every 15 feet of ascent.
That’s about every other breath if you are making the ascent slow enough. We suggest that you not only go slow on every ascent but also flush the loop. How is this done? Simply exhale every other breath through your nose. This will expel the entire exhalation from the system and require the automatic demand valve to replace the whole breath (instead of just 25%) with fresh gas in the loop. This INCREASES the ppO2 of the loop and you have plenty of oxygen for your brain. While we are talking about it think of your re-breather as holding THREE breaths at any one time. This system is not a one for one exchange cycle of inhalation and exhalation. Your exhaled gas “lingers” in the system until it is processed. In effect you are re-breathing several different breaths.

Rule 5 - Dives WILL NOT exceed the Maximum Operating Depth (MOD) of the gas
supply used.
This is the rule that makes the GEM so safe and versatile all at the same time. If you never exceed the MOD you will NEVER have to worry about oxygen toxicity. Because you can easily carry different mixes, this is not a limiting factor for depth or decompression. Here is an example. If you are a technical diver and are doing a deep dive that requires a hypoxic bottom gas you conduct the dive much as if you were using open circuit SCUBA You start the dive on a travel gas (let’s say 32% Nitrox) in a stage bottle that is quick connected to the automatic demand valve of the re-breather. You use this mix ONLY to it’s Maximum Operating Depth. The MOD of 32% at 1.48ata is 120 feet. Because you are conservative, at 100’ you disconnect the 32% Nitrox and connect your back mounted bottom mix of 16/50 and continue your dive to it’s MOD of 268 feet for a very, very long time thanks to GEM‘s gas extension principal! On ascent (you go slowly of course and
flush the loop regularly) you switch back to the Nitrox 32% stage bottle at 100 feet and decompress to 20 feet where you have dropped a bottle of 100% oxygen. At that point you connect it to the re-breather and finish the decompression. You ONLY connect to the 100% bottle above it’s MOD of 20 feet.
Maximum dive time is increased due to the gas extension effect at any depth and the ability to decompress on different mixes. There are many advantages but remember this DOES NOT reduce your decompression obligation!

Rule 6 - The re-breather loop must NOT be used on the surface.
If you are gearing up, or waiting for others to get ready for the dive you must resist the temptation to breathe on the loop. Breathing above 1ata on air or at atmospheric pressure on any gas mix can make the loop turn hypoxic as we explained in rules 1, 3 and 4. After extended surface breathing you could find yourself unconscious under 5 feet of water after starting the dive!

Rule 7 - Always do at least a 5-minute safety stop at 15 feet and start the safety stop by flushing the loop.
Flushing the loop before starting the safety stop assures that the O2 partial pressure in the loop is as high as it can be. This helps off gas nitrogen (or another inert dilution) and helps insure that your tissues and brain are oxygenated. The 5 minute safety stop gives your body almost two blood circulation cycles to clear any excess inert gasses. On to our final but most important rule.

Rule 8 - Keep a log of time used on the scrubber material and never exceed it‘s
exhaustion time.
If you don’t know how many hours are on the scrubber material it is far better to replace it with new. Keep a log of hours used, keep it up to date and keep it written on the scrubber container. Failure to replace exhausted scrubber material will prevent the re-breather from functioning as intended and keep it from removing CO2 from the breathing loop.

Rule 9 - Notice problems. If you detect any problem before, during or after diving the GEM - take care of the problem IMMEDIATELY!
The GEM is one of the safest re-breathers but it is NOT open circuit SCUBA. You must be sensitive to the system and your body. You must understand how the GEM works and how it interfaces and reacts with the environment and your body. Because of it’s clever and simple design you will FEEL problems rather than read about them on a computer screen. You must learn to recognize any malfunction and take action to correct the situation. Training is important and so are conditioning experience dives at moderate depths in open water so that you know how to react to problems when the going gets rough, deep and dark.

Fault Detection
The GEM reacts to any fault situation by changing it’s response to the diver. Let’s take a very simple fault situation to illustrate this point - a mouthpiece that is not exhausting gas. First of all, like open circuit SCUBA you will get used to seeing a stream of bubbles coming from the mouthpiece. Using open circuit SCUBA the stream is very large but it’s only a small trickle with the GEM. You will most probably notice if you are not producing bubbles but let’s say you are not paying attention. On a normal dive you will be conditioned to hear and feel the demand addition valve adding gas on a regular basis. In this fault situation the GEM changes it’s normal response by not adding gas to the breathing loop. The fault situation should be immediately obvious and you take action to correct the problem. This is why a series of shallow “experience” dives are so critical. Experiencing how the GEM reacts when functioning correctly on a normal
dive will enable you to better diagnose when there is a problem. This philosophy of fault detection was not a mistake, it was carefully built into the re-breather to give you a fail-safe, simple and clear method to detect and diagnose problems. Really you should consider you and the GEM one unit - the Diver/GEM unit. By the way, the proper response to the fault above is to exhale through your nose or bail out to the open circuit system and abort the dive.

Now, let’s look at some problems, how the GEM reacts and how you should diagnose the fault and react.

Fault: The Demand Addition Valve is NOT adding gas
GEM Reaction: You will not hear or feel the valve adding gas and since it is not adding, the volume of gas in the loop will get smaller on every breath and you should notice that there is less volume in the loop to breathe!
Your Diagnosis: Check to see there are still bubbles exhausting from the mouthpiece. If so, then it is not likely a problem with the mouthpiece. Check your SPG and confirm you have plenty of gas in your cylinders and the valves are on. If the mouth piece is exhausting bubbles and your valves are on and you have plenty of gas in your cylinders, then the problem must be the ADD VALVE.
Your Reaction: You have two different correct responses to this situation. 1. You can add gas to the loop manually (if you have the manual add) thus essentially bypassing the demand valve. This is a fairly natural fault correction technique because if the volume of the loop gets low (the system is harder to breathe) you simply add more gas. The GEM will release excess gas if you add too much. 2. Close the GEM mouthpiece and bail out to the open circuit system and abort the dive.

Fault: The demand valve is free flowing
GEM Reaction: The loop is at maximum volume and gas is bubbling around your lips and the mouthpiece. You can also hear the auto demand valve adding continuously.
Your Diagnosis: There is a free flow in the automatic demand valve.
Your Reaction: Disconnect the quick connect fitting to the automatic demand valve. This will stop the free flow and save any gas that may be lost. At this point you have two options. If you have the optional manual addition valve you simply add gas to the loop as it is needed to maintain volume and abort the dive. Or you can bail out to the open circuit system.

Fault: The scrubber is flooded
GEM Reaction: If excess water has collected in the scrubber chamber you will experience resistance to inhalation because of its design. The resistance is caused by your trying to draw gas through the water in the chamber. The water in the chamber will inhibit the removal of CO2 by the scrubber and you may also notice the signs of hypercambia, or increased levels of CO2 in the loop. This is usually experienced as abnormally fast breathing and/or head ache.
Your Diagnosis: If the VOLUME of the loop seems to be normal but breathing resistance is noticeably more difficult and the Automatic Demand valve is adding gas as normal, then the most obvious culprit is a failure of the scrubber to remove CO2.
Your Reaction: The only solution to this problem is to close the re-breather mouthpiece and bail out to open circuit and abort the dive.

Fault: Too much CO2 in the loop
GEM Reaction: The GEM will seemingly function in a normal manner. However, you should notice changes in your body. Your breathing rate will increase abnormally and out of proportion with the workload. You may also develop a severe headache.
Your Diagnosis: If the GEM is functioning normally and breathing difficulty has not changed the most logical assumption is that your physical symptoms are due to abnormally high CO2 in the loop.
Your Reaction: The only acceptable solution is to bail out to the open circuit system, at least until you find the cause of the problem. This fault can be caused by several different agents. First of all you could be under a very heavy work load and overpower the scrubber by a rapid rate of respiration. Second, you could have neglected to log the amount of time on your scrubber material and it is no longer removing CO2 from the breathing loop. Third, the scrubber material could have been dated and past it’s intended shelf life when you loaded it. Fourth, during transportation (or for some other reason) the scrubber material has developed channels that allow a large amount of exhaled gas to go through untreated. The best solution is to bail out, abort the dive and find out the nature of the problem!





GEM Fault and Solution Table

Fault Diagnosis Action
Mouthpiece is NOT Exhausting No bubbles, System not adding gas Bail out and abort dive*
Demand valve NOT adding gas Volume of gas getting smaller, mouthpiece exhausting normally Bail out and abort dive*
Demand valve free flowing Loop at overfill volume, gas bubbling out mouth Bail out and abort dive*
Scrubber flooded Abnormal breathing resistance, symptoms of excess CO2 in the loop Bail out and abort dive
Too much CO2 in the loop Abnormally fast breathing, headache Bail out and abort dive

* After taking the technical course you will have other action options to correct the fault.
Gas Reserves
When diving with the GEM you must base gas reserves on the actual amount of gas in your cylinders NOT on the extended gas available in the loop. The best way to correct a problem in most circumstances (and the only option with flooded scrubber or too much CO2) is to bail out to the open circuit system. So, at any point in the dive you must be able to switch to open circuit and have enough gas to abort the dive safely. For open water recreational diving in a familiar area 700psi as read on your SPG will probably be adequate. Even though you will effectively have 2100 psi of gas through the loop you can not be assured that the loop will function normally! Reserve more gas when conditions are more difficult, the dive is deeper or the diving area is not as well known.



Decompression
Do not practice staged decompression on the GEM unless you are certified in that area and have taken the GEM technical certification course. In addition you must use air tables or air computers for decompression calculations when making no decompression dives.

GEM Assembly
1. Pack the scrubber - Open the lid of the scrubber chamber and fill the compartment with your choice of scrubber material. Fill the scrubber in stages adding scrubber material then tapping the side of the housing to tamp the material, then add more scrubber material and repeat until the scrubber is full. Remove the “O” ring from the housing lid and make sure it is clean, then replace the “O” ring and close the container. If you must transport a loaded scrubber, keep the scrubber container vertical during movement.
2. Attach the scrubber to the mounting system. If you have the integrated weight system or other buoyancy system attach it now.
3. Attach the intermediate hoses to the scrubber and counter lungs. Anytime you are attaching hoses make sure they are secure.
4. Attach the counter lungs to the harness system.
5. Attach primary breathing hoses. Now is also a good time to attach and/or adjust primary hose weights.
6. Attach gas supply. Use the quick connect fitting to securely attach the starting gas supply to the automatic demand valve.
7. Ready all stage bottles or other gas supply. Rig each stage bottle with a first stage regulator that has a hose with quick connect and an SPG.
8. Turn the starting air supply on. Open fully the valve(s) of the bottle(s) that will be the starting gas supply.
9. Take a few breaths off of the GEM then Close the mouthpiece. You are checking the system to see if it will hold pressure. DO NOT CONTINUE BREATHING ON THE LOOP!

Pre-dive Safety Check
When suited up and ready to dive check or have your buddy check the following for proper operation:
W - Wings-check that you can inflate and deflate your wings or buoyancy control system. Take a few breaths off the open circuit bail out regulator to make sure it works.
A - Addition Valve-Make sure the starting gas supply is connected securely to the Automatic Demand valve
L - Leak Out-Submerge your primary and stage bottles (if any) and check for gas leaks anywhere in the system.
L - Leak In-Check the scrubber for leaks. Insure that water has not entered.
S - Safety Check-Do a standard SCUBA safety or “S” drill.
If you’ve been keeping up that spells WALLS.

navyhmc
08-18-2009, 19:06
Long post, I know, but interesting reading. Cool system, I'd love to try it. Unfortunately, I don't have $2000 lying around :smiley19:

Scuba Pete
08-18-2009, 19:22
I was right a GEM. There was a post over on Cave divers forum I believe about it. It was from the gentleman that made it. It looks like a very nice unit. There were 2 mouthpieces 1 was for the recreational diver and 1 for technical diving. I believe that you had to take some sort of technical training from the company to get the new mouth piece. With a $2000 price tag, it makes it within reach for most technical divers, and some recreational divers. I would love to try that unit.

navyhmc
08-18-2009, 19:26
You Da Man Scuba Pete! OF course, so is CWSWine, Cummings 66, Mike S....

skdvr
08-18-2009, 21:26
There is no page for it yet... The instructor that I am going to be using for my cave course (SLIM) uses a GEM. He has been using it for a little over a year now (I think) just helping out with the testing... There is an interesting read about some exploration they were doing in Mexico using the GEM. You can read it here (http://www.cavediver.net/forum/showthread.php?t=9740&highlight=gem).

Phil

CWSWine
08-18-2009, 21:40
There is no page for it yet... The instructor that I am going to be using for my cave course (SLIM) uses a GEM. He has been using it for a little over a year now (I think) just helping out with the testing... There is an interesting read about some exploration they were doing in Mexico using the GEM. You can read it here (http://www.cavediver.net/forum/showthread.php?t=9740&highlight=gem).

Phil

Adam was on that same team cave diving in Mexico and he is the one we are working with.

skdvr
08-18-2009, 21:49
From my understanding the guy who builds them (Mike) is one heck of an engineer... He builds some nice lights and scooters as well... I have not seen any of them yet, just heard about them...

Phil

mm_dm
08-19-2009, 07:41
Here you go guys - this is a link to more info.

Rebreather - Beaver Divers (http://beaverdivers.ning.com/forum/topics/rebreather-1)


Beaver Divers:smilie39::smilie39::smilie39: (I'm sure they meant....nope, nope, shut up Mike)

Flatliner
08-19-2009, 08:18
Here you go guys - this is a link to more info.

Rebreather - Beaver Divers (http://beaverdivers.ning.com/forum/topics/rebreather-1)


Beaver Divers:smilie39::smilie39::smilie39: (I'm sure they meant....nope, nope, shut up Mike)

It's on the T-shirts at the shop...

More info.

The RB is a semi-closed unit that mechanically purges part of every exhaled breath based on orifice size. The breathing supply is provided via a drysuit hose to an additional regulator that is part of the loop. The method the mouthpiece uses to do the purge is truly simple and ingenious. You still use your regular reg set up so you have built in OC bailout available. You change mixes by changing cylinders. In my mind, it is a nice solution for a photographer or someone who wants to dramitacally increase bottom times without increasing tank size. That said, I am not sure it is for me yet.

2000 INCLUDING training is very tempting though...

PS, Dennis won't plug himself BUT his shop is going to be a dealer and trainer.

mike_s
08-19-2009, 08:27
I know very little about rebreathers so tech questions I can not answer but I do know that going below 25%/75% was not recommended for rec diving. You change percentage by changing the mouth piece, they do have mouth pieces that go down as low as 10%. I would have to learn a lot more about rebreathers before I would take below pool depths.


when you say "change the mouthpiece", you talking about the orange part in the pic, or the whole assembly that the mouthpiece/hoses attach to?

Flatliner
08-19-2009, 08:32
I know very little about rebreathers so tech questions I can not answer but I do know that going below 25%/75% was not recommended for rec diving. You change percentage by changing the mouth piece, they do have mouth pieces that go down as low as 10%. I would have to learn a lot more about rebreathers before I would take below pool depths.


when you say "change the mouthpiece", you talking about the orange part in the pic, or the whole assembly that the mouthpiece/hoses attach to?

You don't actually change the mouth piece, you change the oriface in the mouth piece if I understood correctly.

skdvr
08-19-2009, 10:24
2000 INCLUDING training is very tempting though...



Yes it is... I will have to talk to SLIM about it and take a closer look at it....

Phil

Flatliner
08-19-2009, 13:05
Phil,

They said you could do tech diving with it. Changing gas by changing bottles underwater. In my mind though, if you are doing serious tech diving, this is not the RB for that. Like I said though. It is an interesting idea and may very well find a valid place in the market.

Robert

skdvr
08-19-2009, 13:36
Yeah, I agree I do not think that this is THE product for deep open water use. A CCR of some type would be better suited I would think. Although this little unit seems to fit well into the Cave Diving world...

Phil

navyhmc
08-19-2009, 16:42
I do hope that a market opens up for this. I'm anxious to try it and maybe dive it!

skdvr
08-19-2009, 16:52
I do hope that a market opens up for this. I'm anxious to try it and maybe dive it!

Head over to midwestdive.com or cavediver.com and ask SLIM about a try and dive at TRL. I am sure that he could put something together...

Phil

Scuba Pete
08-19-2009, 17:27
If i understand the GEM i think it works similar to the RB80 that the WKPP uses, as well as the OCDA (Ozark Cave Diving Alliance, Similar to WKPP). The RB80 has been to 300' plus. If that is the case then depth should not matter.

Flatliner
08-19-2009, 18:29
I'm not saying I think it CAN'T go deep. However, for that type of diving I think that an eccr or OC would be a more effective choice. I can open my front door with a screwdiver and a hammer but my house key works better.

skdvr
08-19-2009, 18:51
Look at a CCR as a Nitrox blending machine that you wear on your back and it is always giving you the best mix for your depth. With the SCR you pick the mix that you want to use but are limited by the PPO2. So yes it can go deep but a CCR is much beter suited for the task. Some people like the easier bailout on SCR espically ones like this and the RB80 since you can use the gas that is supplying the RB as bailout gas.

Phil

bigman241
08-19-2009, 20:10
:smilie39::smilie39::smilie39::smilie39::smilie39:
Ya but why use the keys when a couple 00 buckshots will work. :smiley20:
I'm not saying I think it CAN'T go deep. However, for that type of diving I think that an eccr or OC would be a more effective choice. I can open my front door with a screwdiver and a hammer but my house key works better.

cummings66
08-20-2009, 18:30
I saw the unit, but I'm still of the opinion that I don't trust them yet so I never opted in for the pool dive. Knowing myself I'd buy it and frankly I really don't need one. I can see the use for one though, and I have dove with a buddy using it too. It is simple, way too simple compared to what I expected to find.

I also saw Slim using one last Halloween as well.

skdvr
01-22-2010, 08:52
I just thought I would update this post....

Mike sold the Technology to KISS and is now working for them in an engerneering role. They are currently working on C.E. Approval and hopefully getting ready for production....

You can read more about it here (http://www.cavediver.net/forum/showthread.php?t=11721).

Phil

navyhmc
01-22-2010, 11:04
Interesting...thanks for the update. Still looks to be too $$$ for me.