Storing partially used Sorb.

[Westwinds]

I was asked today to join a BBQ and dive at the local spot. There’s not much to see or do but it’s a great place to get wet, train, and configure equipment, in addition to a BBQ with a couple of buddies.

Being new to my rebreather I thought that this would be a great opportunity to get more time on my unit and iron out some minor issues.

The problem is, if I join this dive today I might not get out again for several days. Does this mean that my slightly used sorb would need to be disposed? It seems like a waste. During my training course we were taught to seal our scrubber baskets in plastic so that we could use the remaining time the next day. I don’t recall if I was ever told how long you could store the sorb before it was unsafe.

My question is two fold. How do you store your partially used sorb and how long would you store it before deciding to dispose of it.

Westwinds.

 

[teksimple]

I am totally new to my rebreather (a Mk 15.5 w/Hammerhead) . The rule I made for myself is if I am not going to use it that same day, dump it and start from scratch. Or, if my computer clears, I clear my scrubber. That may change as I get more experience, and more comfortable with storage procedures. In one narrative by Richard Pyle, he describes how he made a mistake in tracking his absorbant usage and paid the price. If you have plenty of sorb and are not on a boat hundreds of miles from the nearest supply, I would forget about being recycle-conscious and start over. If you are cheap, you picked the wrong part of the sport anyway.

 

[Camerone]

Hey -

My Dolphin scrubber, I generally try to pack on a per-day or per-dive basis, but occasionally, I get into the same situation as you're in right now. What I do, in that case, is remove the scrubber from the loop, drain any moisture as best as I can, and seal off the canister with tape around the ports. In the case of an Evo/Inspiration, I'd seal it in a ziplock.

I've used them up to a week later in this case, with no ill effects, and one of my local dive buddies will use them up to a month later. I can't honestly recommend that, and it seems very ill-advised, as 'Sorb is relatively cheap, considering what it does for you He, however, seems to have no ill effects, and will, in fact, use a full packed scrubber several times... I'd personally dump it out long before then, though.

Of course, you know you never want to disturb the packing in the canister while you're storing 'sorb...

The biggest issues I've found with semi-used 'sorb is moisture. The grains can swell and clump, just from the reaction, and, if used too much and stored, it'll eventually distort the canister, causing leaks and failures. I generally err very cautiously on the side of under-using my 'sorb, though, and I usually just pitch it if I'm ever even thinking slight second thoughts.

Have fun getting hours on the unit...if you've got yours, that means I'll have mine any day now, since we ordered them within a few days of one another!

 

[wedivebc]

I can't honestly recommend that, and it seems very ill-advised, as 'Sorb is relatively cheap, considering what it does for you He, however, seems to have no ill effects, and will, in fact, use a full packed scrubber several times... I'd personally dump it out long before then, though.

I don't see why it's such a bad idea. The absorbant is used up by a chemical process from contact with CO2. If you eliminate the CO2 the process stops. The absorbant will continue to react the next time it is exposed but not until then.

The biggest issues I've found with semi-used 'sorb is moisture. The grains can swell and clump, just from the reaction, and, if used too much and stored, it'll eventually distort the canister, causing leaks and failures.

Where did you get that information from? I am not aware of any swelling although some clumping is normal I have never heard of canister damage from swelling absorbant. You're not using jonney-cat brand are you?

 

[Camerone]

I don't see why it's such a bad idea. The absorbant is used up by a chemical process from contact with CO2. If you eliminate the CO2 the process stops. The absorbant will continue to react the next time it is exposed but not until then.

True statement, and I agree with it.

I question a couple of things, however, with his approach. First, scrubber duration is variable, not absolute, and varies with workload, temperature, packing density, etc. Even if he were to keep scrupulous record of his usage time, as he pushes the scrubber towards the "end of life," remaining time is a guess, at best, especially without any kind of monitor (which the Evo seems to solve somewhat). Sorb is cheap, and he pushes the limit of the scrubber unnecessarily, which seems like an unnecessary risk with no reward whatsoever.

Second, your statement presumes he does a good job of sealing the canister from any exchange with the environment. Maybe he does, maybe he doesn't, but I don't presume he vacuum seals his scrubber up when he's done. As long as there's any kind of diffusion path for gas into and out of the canister, the ambient CO2 will continue to react (albeit slowly) with what's in the canister. I keep my unused sorb sealed in an airtight container, and I watch its freshness date (and fortunately dive enough so that it's never more than six months, at the absolute worst, before I've gone through a container...)

Where did you get that information from? I am not aware of any swelling although some clumping is normal I have never heard of canister damage from swelling absorbant. You're not using jonney-cat brand are you?

So _THAT_ explains why my kitty likes the rebreather so much when I'm setting up gear...

Clumping always happens for me after a day of diving. Swelling is either perceived on my part from spilled "litter" when I've been a little sloppy in cleaning up the garage after spilling while filling, or anecdotal from my service tech, who's been working on my unit since it was an Atlantis I...

Anyway, my only real point boils down to, "if there's a question with how much is left, toss it." Sorb is cheap, and life is...well, it can be cheap, too

-C

 

[DrMike]

Keeping the sorb (used or new) inside the unit is no different to keeping new sorb inside its container. The checkvalves/mouthpeice will prevent any air flow (not that there is any flow unless perhaps you put it in a windy place. Theres not a lot of CO2 in the air around us anyway. Keeeping it sealed is done to keep it from drying out.

So what I do is to choose a time I am happy with as a conservative estimate of allowable max scrubber lifetime giving the type of diving I am doing then use the scrubber for that duration keeping it inside the unit always. After diving Ill clean the unit, let the unit dry out for a few hours then reassemble with the scrubber inside then pop it into storage.

This has worked for me fine. The longest time I have had between dives with the same scrubber in this manner was 3 weeks. I know people who have stored scrubbers far longer without issue.

Keeping a track of scrubber usage and changing it when the limit is reached is no different with a scrubber thats been in strorage and one that hasnt.

 

[peterbj7]

Interesting. I've always felt uncomfortable using scrubber after more than 3 or 4 days. No scientific reason, just fear! I think I ran it a week once, though to be fair it was fine. I wonder what the maximum endurance anyone has ever had is? By mistake I ran my Inspiration to 7 hours in the warm water of Belize, with no ill effects.

 

[Pez de Diablo]

Clumping always happens for me after a day of diving. Swelling is either perceived on my part from spilled "litter" when I've been a little sloppy in cleaning up the garage after spilling while filling, or anecdotal from my service tech, who's been working on my unit since it was an Atlantis I...

Anyway, my only real point boils down to, "if there's a question with how much is left, toss it." Sorb is cheap, and life is...well, it can be cheap, too

-C

I don't know about clumping. I live in a place where the dew point is 23 C, the humidity is so great I feel that I am in the shower full time.

I don't have any problems with clumping or swelling. Sorb is not cheap, nor is life. Waste not want not. Don't go overboard and change your sorb out after everydive, this is crazy. As Divebc and myself on another board have mentioned, the sorb is used up when it is in contact with CO2. Don't store your sorb in a high CO2 environment. Write the hours used on the side of the scrubber unit (on packing tape) and keep track of its life that way.

Actually, if anyone would like my address, you can send me all your sorb that has an hour or two on it, I would love to test it for you to see how many hours it has left.

 

[Pez de Diablo]

Interesting. I've always felt uncomfortable using scrubber after more than 3 or 4 days. No scientific reason, just fear! I think I ran it a week once, though to be fair it was fine. I wonder what the maximum endurance anyone has ever had is? By mistake I ran my Inspiration to 7 hours in the warm water of Belize, with no ill effects.

12 hours to the limit over a 5 week period. Did get a bit of break through. I expected it and it happenend. Mexico open water 84 F.

 

[peterbj7]

12 hours! That's going to save me a bundle on Sofnalime.