Sorb-how long do u keep it between dives?

Dave Sutton

I *said* don't do it. It's just one data point done by a stupid diver...

But.... load your scrubber, get blown out, and plan to dive in a week? Toss your powder out if you like, but it's no different being stored in the scrubber than in the keg.

Another data point: I work far more from a volume standpoint with coal mine safety rebreathers than diving rebreathers, and the scrubbers are packed for 5 *years* before a change, ands are carried *every day* on the belt of a coal miner. Continuing, the Biopak 60 and Biopak 240 rebreathers are used for hazardous environment entry and are stored *packed* for years. Ditto every IDA-59 in the Russian Sub Escape Kits, Ditto the RGU F/M scrubbers in the Warsaw Pact armored vehicles. They stay packed for years, and are relied on to save human life.

So, I'm *sure* yours can sit a week in your garage.... .

Best,

Dave

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Ben Field

Very probably all true... I agree that Packed and In the Keg are pretty much the same.

The really vital question is if you dive your 3hour Scrubber for 1/3rd of its duration than park it how long can it be left, can it still be dived for 2hours, can you assume for every X days wait you reduce the remaining dive time by X hours etc?

The guy who was/is on here for Molecular Products skirted the issue IMO.

I think there should be some set figures for this the same there are for scrubber duration.

The vast majority of us seem to be getting away with whatever we're doing- its just crazy that we have numbers/limitations on almost everything except what a used scrubber is good for.

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diverreb

I agree with that and testing would probably be relatively simple. My assumption is that no manufacturer is going to stick his/her neck out and claim any duration once opened because they have no control over the storage method. Once they say that Sorb/EAC's can be used for X weeks after opening if stored properly, they open themselves up to way too much liability in the event a diver for whatever reason stores the sorb/EAC improperly and has an incident from using that sorb/EAC.

That shouldn't stop an independent lab from stating that they tested the stuff after two weeks, one month, three months, etc. after opening, but stored in a closed container, and found the sorb/EAC X % effective after each period. It would also be interesting to see the difference if they also tested for sorb/EAC's stored with say a loose seal or hole in the box for the same time periods, as well as testing against fresh stuff.

But the only people publicly interested in that Data is us, so unless we decide to fund such an endeavor, I doubt we'll see any solid data on the subject.

Richie

Dsix36

I tend to agree with Dave's train of thought about storage for years.

This is my own personal useage and measurements of scrubber (cartridge in my case) so I am not telling anyone to do this. I figure that the absolute max duration on my scrubber is 8 hr. I will use it up to 6 hr and leave a 2hr safety margin. If I use it for 2 hr on a dive and store it for a week until the next dive then I will deduct the 2hr usage and an extra 1/2hr leaving 3 1/2hr of duration.

For every week of storage, I deduct 1/2hr from the duration. This has been working flawlessly for me thus far. Useage has been the same as calculated on all cartridge measurements after diving.

Remember this: I am new to Rebreather and stupid also - do not do this without using your own metabolism to figure sorb use.

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Andy Del

I too like Dave's thinking, so why do so many feel it necessary to bin sorb ater a relatively short period of time?

Using the above as an example, why deduct usage time when the sorb is sealed and has no gas flow through it, just like it was in the original container? It makes no sense to do this. So, if one followed this procedure logically, and applied it to al hte sorb you use, you would reduce the life of any opened sorb container.

So, your typical 20kg keg, if one is diving for two hours a week would reduce itself to zero usage time 12 weeks, based on a 6 hour sorb life. Take the maths and use your scrubber for three weeks (1 x 2 hour dive a week), you get to the point where the sorb can only be used for 1 hour in 10 week. Then you would have to toss it out! (I think I did the sums right, but it's 35C here and the only thing keeping me cool is beer )

So where did I do the sums wrong?

Back to my beer...

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Nailer99

I guess the part that I was wondering about is this:

If I pack a fresh scrubber, and dive for an hour with it, it's theoretically been used to 33.33% of it's rated duration. So, if I seal it up in a bag or somewhere with no airflow over it, does the used sorb start to react with the unused sorb in some way? Is that why I was taught to dump it out if it was a week old? It's the only explanation I can come up with for that rule.

Jim

''I too like Dave's thinking, so why do so many feel it necessary to bin sorb ater a relatively short period of time?''

Hi all,

My reason for dumping partly used scrubber is the same as many on this forum - the last dive was probably at least 90 mins, usually in cold water with varying depths always greater than 35m ..... number one, my next dive will definitely exceed the 3 hour safety net, number two, I use a check list but can't be ***&ed to start recording scrubber used time, and number three, compared to a CO2 hit or worse, six or seven quid a fill is cheap as chips, especially when I'm putting Shell V-Power in my motor at £1.18 per litre !!!

If packed and not dived, I'm happy to leave my scrubber in the unit for months - it never comes to this with a quarry dive replacing blown out dives.

It's just not worth risking life for a few quid - and surely that is what it all comes down to?

Safe diving.

Jimbo

ps £1.18 a litre - can you believe it? Bet you yanks don't have to pay that !!

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nigelh

I would go with Dave and think that fresh 'sorb is fresh 'sorb be it in the shipping tub or my cannister but I confess I do get back from a dive, dry the head, put the top back on and leave it 'till next time. Then, if the three hour clock gives me the next dive, I do it regardless of how long it's been sitting on the bench.

There are a couple of questions in my mind about the humidity of the stack but other than that the chemistry is too dumb to 'go off'. The three minute prebreathe, watching the desperation's temp stick, tells me it's fired up OK.

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nigelh

Marc

I've dived few times (no real deep dives, i.e. up to 40 msw) on a scrubber that was several weeks old with just an hour or so of usage on it...

As said, main points: don't disturb the scrubber bet and keep it sealed so it doesn't dry out...

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Ben Field

No disagreement here on freshly packed unused scrubber.

My issue is it I use the scrubber, making it warm, moist, maybe abit of water in the bottom then cap it and leave it- what happens? Where does the moisture go, how does it actually effect duration remaining, should we take off 1/2 hour as suggested etc?

I ask because lots of people do this- go diving, cap it in the unit, dive it again the next day (its been sat 20+hrs on the boat) as there is no noticable incident rate directly attributed to this it "must" be okay, I'd just like some science and numbers thats all

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