Dive canceled, wasted scrubber ?

edasque

Hi all,

so this past Saturday, I was supposed to go do a little dive but my buddy had to bail out at the last minute (8 hours prior). I was going to dive the next day to make up for it but my other buddy called me to tell me to bring my surfboard instead (rough seas).

I had set up my O2ptima the night before (Friday). I am thinking about diving this Saturday (7 whole days after). I am assuming, that since I have not breathed my scrubber (the loop is still closed) and nothing in my apartment should generate much CO2 anyway, I can just go ahead and dive it.

In those circumstances what's the best thing to do ? Take the scrubber out and pack it again. How long would you be comfortable leaving an unused but unwrapped EAC out (in the loop or re-packed) and still dive it ?

Long winded but you get the gist of it.

Erik

jhaaja

I would just keep the unit ready and loop closed. It is good for diving the next weekend.

I have had the scrubber packed and open for 1-2 weeks between dives without any problems. I would not do a deep long dive with a partially used and 1-2 weeks stored scrubber though.

JH

jdicediver

I agree...see:

http://www.rebreatherworld.com/rebre...e-c02-hit.html

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diverreb

It's not only the lack of CO2 passing through the EAC but also the moisture content of the Cartridge that effects it's ability to work. It has to have a certain amount of moisture content to remain active. If it dries out too much then it looses it's ability to do it's job

That's why it is recommended to remove the EAC if it's not being used and reseal it in it's original bag inside the carton then bag the carton for short term storage. Do people leave the EAC in overnight? Sure they do... But for any longer than a day or two, I'd take it out and bag it.

As far as how long to keep it before reuse... I personally won't use it if it's been out longer than a week.... Especially if it's been partially used. It's one less stress point to have to think about during a dive.

Richie

JCdesign97

The basic principles of the chemical reaction of scrubber materials are essentially the same as stated above (granular 'sorb, I mean); but as far as the EACs in particular it was conveyed to me by several respected sources here on Rebreather World that one to two weeks is what most people consider safe for using a cartridge after you've broken the seal. I have routinely opened and used a cartridge one weekend, bagged and capped it back in the original package post dive (writing on the cap the minutes used and the liters of CO2 scrubbed based on O2 consumed) and then used it again the following weekend, obviously applying a safety factor reduction in the capacity remaining. I have occasionally done the same over a two week period, but I try to plan my dives as best I can to avoid stretching it that long.

FWIW it was also conveyed to me at the time I asked the similar question that some people were using their cartridges as long as four weeks later. That's definitely too long for my personal comfort level, but as I have yet to hear of any EAC CO2 hits, you can make of that what you will. Keep in mind (as I understand it) that it's not the chemical reaction itself that starts when the container is opened - there isn't enough CO2 in air to make that happen. The critical thing is the moisture content of the media itself. If the cartridge dries out too much then the chemical reaction will not be able to start up no matter how long you pre-breathe it or how much capacity was used the first time. By that rationale you need to be aware of WHERE you keep it and how dry it gets once it's opened, just as much as how long. Keeping it in the unit, loop closed is probably not much different than double-bagging it back in the original package, although I have never done this.

For future reference, I NEVER open the container until I am SURE I'm splashing. When I'm in the ocean I usually build and pre-dive the unit the night before, load it on the boat; but I don't put the cartridge in until the morning when the boat is idling out of the dock and I'm RE-doing my pos/neg tests, and then pre-breathe, etc. Land-based is even easier to do the same ... and this is exactly one thing I love about the cartridges in the first place.

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John

Simon A

Erik,
In theory as long as the unused scrubber is stored in a sealed container that maintains the correct humidity and keeps co2 out, it should be good until the use by date.

However the fact that you are asking this question should lead you to consider the two following questions:-

1) What's your life worth?
2) How much will it cost you to throw the unused scrubber?

If you are unsure if the scrubber will be ok after storage, and the answer to question 1 is greater than the answer to question 2. Then the correct path of action is obvious.
HTH
Simon A

Outlaw

hey guys,

are you saying that keeping the scrubber in the can, no use, is not good? are you saying that this will damage the scrubber ability to work fine? where is it stored before then?

very strange...maybe is me.

Spyros

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Simon A

Spyros,
That's not the case at all, the scrubber should be good.
But in my opinion, if you are unsure if Scrubber material (either extendair or sorb) is still ok, then it's time to throw it away and use fresh.
This is also a good line to take with cells. After all, these are the bits you are depending on to keep you alive.

Simon A

Dsix36

I personally like to keep the canister sealed in the loop. I have never stored one for more than 1 week. I also deduct 20% from the available usage for the next dive, just as a safety factor.

I have one in my loop now from the weekend. I intend to use it this weekend.

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Outlaw

Simon,

thanks for your reply. you are right. if 1% unsure, then best to replace. this is a tactic i use. i just wanted to confirm that i had a "right approach" on the matter, as far as having it in the cannister, closed and sealed.

Thanks a lot.

Spyros

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CMAS - IANTD - TDI
Kamikazi Instrustor Trainer
DIRRebreather Team Member
----------------------------
"Once an Outlaw, always an Outlaw"