I would hope that in 2017, everyone would know not to restack used scrubber material
Partially Used Scrubber
- Thread starter oya
- Start date
I would hope that in 2017, everyone would know not to restack used scrubber material
missionmtb
New Member
I use a foodsaver vacuum sealer and a continuous roll of plastic film to save my partially used scrubber. Ignoring the gas permeability of the film, this should eliminate CO2 adsorption from the atmosphere. As long as it sucks air in when I open it I figure the vacuum held.
Sealer's ~$150, plastic rolls are ~$10 on amazon.
This also works well for keeping 3d printer material dry
Sealer's ~$150, plastic rolls are ~$10 on amazon.
This also works well for keeping 3d printer material dry
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Regardless of whether you choose to store partially used scrubber, you should under NO circumstances ever dump the sorb out of your scrubber and then repack it. There are numerous examples of CO2 hits due to this UNSAFE practice.
nickb
The JJ Kid
I don’t think anybody’s advocating reusing lime that’s been removed from the scrubber. That’s just asking for trouble.
Mr.Dave
New Member
As quite a few divers store partially used scrubber for a number of weeks between dives (inc me). Without published research we are taking on the assumption that storage won't of had a detrimental effect on its useful life or we make a guess to what we feel the useful life has been degraded to.
Some research and published guidelines into this is long overdue.
Some research and published guidelines into this is long overdue.
MadUKDiver
Member
Mitchell and Gant's presentation did also address the subject of scrubber storage. A previous reference they cited was a Canada Defence document that concluded "Storage sealed in a rebreather for one week cause no change in duration".
They performed an experiment to test "overnight open" and "1 month, open and sealed" storage of Inspiration (Sofnolime 797) canisters with 90 minutes of prior use. Their ambient atmospheric condition was 20 degC, 60 %RH, 0.03% CO2. After 28 days storage the "open" stored canister showed approximately 40 minutes less duration than the "sealed" stored canister. The overnight "open" canister was very similar performance to the 28 day "sealed" canister. Their summary:
Outcomes
Storing a scrubber between dives can influence CO2 absorbing capacity
Prolonged storage (28 days)
Sealing scrubber from the atmosphere increases scrubber endurance
Brief storage (overnight)
Unprotected scrubber performance is equivalent to a sealed scrubber after 28 days storage (implying that overnight unprotected storage is OK)
It is probably fair to summarise as follows .. if you are intent on storing scrubber canisters between dives and are faced with a moderate lay over then storing sealed is a very good idea but you don't have to be worried about overnight storage.
IIRC an interesting observation that was discussed but not part of the presentation was that the baseline test - fresh pack and consume in a single operation - gave approximately 200 minutes duration (under their test criteria). The "28 day sealed" and "overnight" canisters gave slightly over 220 minutes duration. I believe it was Neil Pollock who suggested a hypothesis that not all of the reactions happening in the Sofnolime are occurring at the same rate and therefore introducing a 'dwell' might allow some element of 'recovery'. It is important to note that there was no repacking of any scrubber canisters. This observation has no practical use to CCR divers which is why it was not directly referenced in the presentation but the graphs do clearly show the different end point duration's.
Simon and others have presented this at a number of venues around the world and I would encourage everyone to attend a session. Not only to hear first hand from the experts but also to support their work. Waiting for snippets to leak out on forums opens the door to recollection errors and opinion bias.
MadUKDiver
Member
You must have missed the "scrubbermise" thread on RBW some years ago. This is one of those subjects that simply can't be discussed objectively on a public forum which is why that thread got deleted just as it got interesting. IIRC the proposer of the 'method' could not present any supporting data except "he was still alive" but (ignoring the emotional outcry) none of the objective counter arguments appeared to devalue the proposal. It would have been interesting to see the 'method' to subject to the Mitchell test regimen.
nickb
The JJ Kid
I meant within this thread.
I'm well aware that there are idiots out there who think they've sussed out a foolproof method to save themselves a couple of quid. For instance by scraping out the first 1/3rd of the scrubber canister 'cos that's where they used it on the previous dive.
Gavin Anthony, as I recall.
I'm not sure that's what he said, or meant, though. See also Le Chatelier's principle.
MadUKDiver
Member
Thanks, you have a better memory for names than I do. And for sure what I think I heard may not be what they said or meant.
The chemical reaction is detailed on the Molecular Products 797 technical datasheet and there's a nice article available here.
Uwe Sieg
UweS
Due to the inaccuracy of scrubber performance filled with sorb, both of my RB's types I dive are using pre-packed cartridges. These cartridges are very accurate re packing & ,consequently, performance.
Since we cannot accurately measure CO2 in the loop as yet, (development in progress) it is important form me to have repeated accurate scrubber duration. As long as the scrubbers are stored without the possibility of drying out, these scrubbers can be used according to the specified manufacturing use-by date.
I store used scrubbers within Zip Lock bags to prevent drying out as well as in the provided containers.
Since we cannot accurately measure CO2 in the loop as yet, (development in progress) it is important form me to have repeated accurate scrubber duration. As long as the scrubbers are stored without the possibility of drying out, these scrubbers can be used according to the specified manufacturing use-by date.
I store used scrubbers within Zip Lock bags to prevent drying out as well as in the provided containers.
I'm curious what you mean by this?
Uwe Sieg
UweS
This statement is based on the ExtendAir Reactive based Cartridges (RPC) by Micropore research as stated in their documentation.
In short it claims that due to the design of the scrubber (Air Flow Channels and density of absorbent material) "At a minimum, duration is improved by 25%". Also, due to the elimination of channeling "an RPC's mean duration is repeatable to +- 5% within two standard deviations, while granular performance is no better than +- 30%".
DR has recently released a cartridge container for the O2ptima which can be used with either Sorb or Cartridge. In typical average temperatures of 20% C I dive in, this would mean that I would use the cartridge for 4 hours but, if I would switch to sorb, I probably would have to reduce the duration of my scrubber by 30% or +- an hour to be save.
How I am hoping that we could buy a CO2 analyser which is accurate at all depths. This would finally lay all claims and guessing work re scrubbers to rest.
I would keep in mind that the "study" was conducted by Micropore and would at the very least should be considered "marketing material". Simon Mitchell recently presented at OzTek, refuting Micropore's claims of superior cartridge duration vs. granular duration.
oya
Member
Randy, are you suggesting that a for-profit company claiming that its product is superior would deliberately release skewed data supporting their claims that their products are superior?
That is weird! At least they're not PDFs.
oya
Member
I didn't mean to suggest you were implying the company was outright lying. I was making a joke that fell flat about how data can be read to prove anything and can sometimes demonstrate conflicting information that can be cherry-picked for marketing.
But having to explain the joke means the joke wasn't funny. Oh well. One day!