extend air CO2 absorbant

[TechBlue]

My official capacity with the company is test diver and and I am working very closely with them on a unit I am building which will be designed around their scrubbers in addition to developing the adapters for the KISS, the test results from Martin should be out soon. MikeR these cartridges have been around for a few years in the dive industry, NASA uses them and they have been used in Submarines by a number of navies, the technology is sound, what we are trying to do is use testing that can be used as a reference for all RB divers which will be provided with graphs relating to temps, depth, workload and of course duration. the ultimate cartridge of course will be radial but I'm not sure when exactly we will be seeing that.

Chris

Chris

 

[solodyver]

Happy New Year and thanks for the email.

The canister duration is everyone's biggest question, the "real world" duration is obviously different for each diver and each set of dive conditions. To cover all potential scenarios most equipment manufacturers test the canister at conditions that most users cannot exceed. We test at a breathing rate of 40 L/min (an Olympic athlete can maintain that rate for about 10 minutes) and water temperature of 8 deg C. At those conditions we know that every cartridge will give at least 120 minutes of bottom time before reaching a CO2 level of .5%. The reality is that on a typical dive you will get more bottom time than that.

Draeger started out rating their canister at 120 minutes and has now moved to 180 minutes. We also have a new cartridge that we call Extended Performance (EP) that will last longer than our 2 hour product. Users have reported getting 4 - 5 hours of bottom time from the 2 hour in warm water diving and 6 - 8 hours with the EP cartridges.

You can dive our cartridge the same way that you dive with granules in that you "learn" your scrubber life based on experience. If you can determine your personal CO2 production that can give you a better picture of what to expect in typical dive conditions.

This is a long answer to your question, most canister durations are rated conservatively to protect the diver.

As to using a scrubber for more than one dive over some time period, all that I can tell you is that many people do that and our absorbent should be used the same way as granules. I personally will keep a cartridge in my rebreather for a weekend of diving and keep track of time on the cartridge. I am not comfortable with going much longer, but that is personal preference. All absorbents have a moisture content that needs to be maintained to work properly. Once the absorbent is exposed to the environment you should use it as soon as possible. The longer it is exposed the less you know about how it will work. This is one advantage of single use packaging so you only open what you intend to use.

I hope this gives you more insight into the differences between our product and granules, let me know if you have other questions.

Best regards,

 

[caveseeker7]

We test at a breathing rate of 40 L/min (an Olympic athlete can maintain that rate for about 10 minutes) and water temperature of 8 deg C. At those conditions we know that every cartridge will give at least 120 minutes of bottom time before reaching a CO2 level of .5%.

I wonder at what depth the testing is done as the ambient pressure figures into cannister duration.

Draeger started out rating their canister at 120 minutes and has now moved to 180 minutes. We also have a new cartridge that we call Extended Performance (EP) that will last longer than our 2 hour product. Users have reported getting 4 - 5 hours of bottom time from the 2 hour in warm water diving and 6 - 8 hours with the EP cartridges.

Dräger ratings for the US are 3 hours for the Dolphin and 70 minutes for the Ray (2,25kg and 1,125kg of Dräger DiveSorb, respectively). For Europe and Egypt the cannister durations were raised last year to 4 hours for the Dolphin and 110 minutes for the Ray (at a respiratory minute volume of less than 30 liters/minute, no ambient pressure or temperature of testing conditions given :angry: ).
Don't know if that's what is meant by conservative, law suit preventing rating
or if this is a law suit encouraging rip-off to sell more absorbant ... .

At least here we know that there is a difference between the (US) rating and test results (as I doubt they rate past those in other countries). But there is no saying how APDs, ISCs etc. tested and how close the results are to the ratings as they don't publish the test results . For all we know the Inspiration might have averaged 3hrs 11min, with a +/- deviation of 8 minutes ... we just don't know.
So we're back to the same old square one we've been all along.

I for one am looking forward to the publication of the ExtendAir test results, at least then users will know where they are when using them.

 

[MikeR]

Hi Guys,

sounds like a great option. Was there anything ever said about them fracturing at the deeper depths in the inspiration, seems like I heard that somewhere. Cant remember where. Not starting anything just got that in my head and its bugging me. Thanks

 

[TechBlue]

Hi Guys,

sounds like a great option. Was there anything ever said about them fracturing at the deeper depths in the inspiration, seems like I heard that somewhere. Cant remember where. Not starting anything just got that in my head and its bugging me. Thanks

Mike,

I think what your are remembering is a post from Martin after DEMA, and it was in reference to the Inspiration scrubber housing, the original design for the adapters had an o-ring top and bottom which would have potentially have created a problem because like all rebreathers the scrubber was designed to work under ambient pressure, the o-ring would have created an airlock which may have caused the Inspiration housing to be crushed. The lower o-ring is no longer used and that solved the problem.

Cheers,

Chris

 

[TechBlue]

More a post for local people and any who will be at BTS we will have a booth showing a number of rebreathers, we will also have ExtendAir with us and Tom McKenna will be there to answer any of your questions.

 

[landfish]

is there a problem with your site?
i cant see any of the pics?

 

[fins wake]

To cover all potential scenarios most equipment manufacturers test the canister at conditions that most users cannot exceed. We test at a breathing rate of 40 L/min (an Olympic athlete can maintain that rate for about 10 minutes) and water temperature of 8 deg C.

Most users in Northern Europe would find 8 dec C rather warm. I'd be more comfortable with at least 4 dec C, something which is easily exceeded in the shallows here in winter.

 

[TechBlue]

is there a problem with your site?
i cant see any of the pics?

Everything seems to be fine, please let me know if you still have trouble seeing the pics.

Chris

 

[BigJetDriver]

Most users in Northern Europe would find 8 dec C rather warm. I'd be more comfortable with at least 4 dec C, something which is easily exceeded in the shallows here in winter.

Fins,

I knew you folks over in Northern Europe were nut cases, now I know why. You've been over there inter-breeding with Polar Bears for far too long! Four degrees Centigrade and below...my a**!!!

BJD :anakinpod