extend air CO2 absorbant

[DrySuitDave]

The training is a little overstated it is a simple matter to replace your existing scrubber with the ExtendAir unit, check your o-rings and seals, slide the cartridge in lock the canister lid and you are ready to dive. You do not need to do any kind of certification or pay for a course to use the cartridge. You do need to be certified on the rebreather you are using and we do require that all users sign a waiver, again SOP for anything to do with RB diving.

Chris

Chris,

At DEMA AP showed an Evolution scrubber with an Extendaire cartridge. I take it this was made with some means of having their C02 thermister down the center axially. I know AP has a new scrubber housing for the Inspiration that employs their new scrubber head and electronics. So here is my question...

How can an Extendaire cartridge absorb more C02 then an equivalent displacement loose fill of either 4-8 or 8-12 mesh absorbent. If it is more denslley distributed, then how does that affect breathing resistance, and if it not more densley packed, is the surface area available larger then an equivalent displacement of loose fill absorbent?

I personally have never had any issues with improper cannister filling, channeling, caustic cocktails, etc. Since absorbent is already expensive, the only way I can justify the additional expense is if per $ spent I can get more run time to the point of equivalency.

Without some properly conducted comparison, then using manufactuers suggested run times when one manufactuers liability carrier and counsel may be more conservative then anothers, it makes for a poor comparison versus such and such scrubber absorbed so much C02 for so long.

If all else is equal, I would prefer to use the cartridges.

 

[TechBlue]

Dave,
Martin has the cartridges in house as we speak, there were some minor changes to the adapters which are now done and we all eagerly await Martin's blessing as this is the only "unbiased" testing that all you Inspiration guys will unconditionally accept. The cartridge is being tested against 8-12 mesh for point of reference. The cartridges are a rolled extrusion with the medium suspended in the plastics allowing a marked improvement in work of breathing. By the same token Leon Scamahorn of Innerspace Systems (Megalodon) and Kevin Gurr(Osoboros) have both whole heartedly embrassed the technology and are both looking at radial cartridges for their rebreathers. The Meg will also be able to use the standard cartridges, I myself am working on an adapter for the KISS rebreather to use the cartridges, for my money they are well worth the additional expense.

 

[DrMike]

Dave,
Martin has the cartridges in house as we speak, there were some minor changes to the adapters which are now done and we all eagerly await Martin's blessing as this is the only "unbiased" testing that all you Inspiration guys will unconditionally accept. The cartridge is being tested against 8-12 mesh for point of reference. The cartridges are a rolled extrusion with the medium suspended in the plastics allowing a marked improvement in work of breathing. By the same token Leon Scamahorn of Innerspace Systems (Megalodon) and Kevin Gurr(Osoboros) have both whole heartedly embrassed the technology and are both looking at radial cartridges for their rebreathers. The Meg will also be able to use the standard cartridges, I myself am working on an adapter for the KISS rebreather to use the cartridges, for my money they are well worth the additional expense.

I wonder if the new thermisters will still work on the cartridges? I can see how loose lime grains will make a good contact and allow heat transfer, but how will the cartridge? Can heat disipate radialy across the cartridge? Will the inner cartridge make a good enough fit to the thermisters to allow reliable sensing?

I have no prob with the lime. If the cost/dive hour works out the same Ill buy cartridges just because of ease of fill, otherwise I wont. I imagine circular cartridges in square boxes will take up more space that a keg of lime for transport - thats important to me. Looking forward to seeing them.

Cheers
Mike

 

[DrMike]

Dave,

I wonder if its because the uniform passageways thru the cartridge ensure a more uniform gas distribution and so a higher percentage of the lime present sees the gas. In a loose fill maybe there is dead space or areas of reduced flow where lime doesnt see gas flow before it breaks through someplace where the lime is used.

Pure speculation of course

Cheers
Mike

 

[TechBlue]

Dave,

I wonder if its because the uniform passageways thru the cartridge ensure a more uniform gas distribution and so a higher percentage of the lime present sees the gas. In a loose fill maybe there is dead space or areas of reduced flow where lime doesnt see gas flow before it breaks through someplace where the lime is used.

Pure speculation of course

Cheers
Mike

Mike,
Fairly close, the cartridges will cost more than the lime by about 20-25% the price of sofnolime and dragersorb has been dropping we like to think that it is anticipation of the cartridges. I'm not sure how the thermistors are going to work with the cartridges, for one thing the center hole has to be plugged to stop channeling so there would have to be a seal if the thermistor runs down the center of the catridge. Again I'm still not sold on the sensors, as Joe said when the sensor tells you its over, its over you have to switch to OC. As I'm sure you are aware, you can't be cheap when it comes to your scrubber or sofnolime usage, when in doubt toss it out. Most of our diving is in the 200' to 250' range and we dump the scrubber after each dive, the cartridge is a lifesaver for that kind of diving, there will be two cartridges available the 2 hour and the extended range, testing is still out on the extended range but rest assured as soon as we have it we will be putting out for everybody to see.

Chris

PS I will be talking to Cliff on Tuesday and I will try and get some more definitive information on the thermistor.

 

[BigJetDriver]

The only problem I see with the cartridges is that they do not last as long as a loose-fill canister, and they cost more. They are, however, somewhat more convenient!

BJD

 

[TechBlue]

The extended range cartridges do last longer, we are waiting for Martin to release the "official" test results.

 

[BigJetDriver]

So, from my interview with a company representative to now, what, exactly, has changed? When I spoke to the gentleman at the company's booth, he quoted me a figure that was not as long in duration as the loose-pack full-size Inspiration canister? Que es esto, amigo?

BJD

 

[DrMike]

Again I'm still not sold on the sensors, as Joe said when the sensor tells you its over, its over you have to switch to OC. As I'm sure you are aware, you can't be cheap when it comes to your scrubber or sofnolime usage, when in doubt toss it out. Most of our diving is in the 200' to 250' range and we dump the scrubber after each dive, the cartridge is a lifesaver for that kind of diving, .

Hi Chris,

Fully agree, however I do see real potential benefit in the sensor. The bar graph will show you how much of the scrubber has been used up so it will be easy to safely build up knowledge on how long the scrubber actualy lasts for a given diver, for the diving hes doing. I dive warm waters and have never used a scrubber more than 3 hours (usualy ends up binned after 2.5 due to the dive sites Im doing) so I am probably being quite conservative. The bar chart will show me if this is the case and will I presume allow me to determine what a more realistic (for me and my diving) scrubber life is.

I am hoping to be able to extend the scrubber usage Im getting by 25% so that I can justify to myself the extra cost of the extendair cartridges!


PS Have you sent out the unit?

PPS I am currently in the airport lounge Heathrow on my way home after having just checked in 60kg worth of softnolime an O2 tank and a gas connection system! Luckily I get stacks of extra weight allowance, and with the customs tax rebate its saves me around 50% of what I would pay back home!!

It was really nice to meet Martin and Nicky and have a nose around at what they are doing at their factory. Nice people, they made me feel very welcome.

Cheers
Mike

 

[DrySuitDave]

I talked to Cliff at Silent Diving and he inferred that AP did some tests and found that diving in warmer water then the scrubber was tested and rated to doesn't increase the scrubber duration as the scrubber is so well insulated. That has to be a benefit to a thermoplastic scubber housing, as plastic has a poor heat transfer coefficient thus making it a good insulator compared to metal.