Northwest Dive Club

I've got 2 kegs of 7/2020 Sofnolime for 100$ ea if anyones interested. Take both for 150$

Is this the same Sofnolime 797 CO2 Absorbent 8-12 Mesh Granules, Non-Indicating (44 lb | 20 kg) that are found online for $150/single keg?

I am working to the bottom of one and have another unopened but this sounds like a good deal

What's the date on the kegs Jeff?

its right in the post

Stuff lasts for well past expiration. I'm still using 2019 stuff.

eh.haole wrote: ↑Tue Aug 11, 2020 4:32 pm Is this the same Sofnolime 797 CO2 Absorbent 8-12 Mesh Granules, Non-Indicating (44 lb | 20 kg) that are found online for $150/single keg?

I am working to the bottom of one and have another unopened but this sounds like a good deal

Sofnolime 797.

Jeff Pack wrote: ↑Wed Aug 12, 2020 6:40 am

eh.haole wrote: ↑Tue Aug 11, 2020 4:32 pm Is this the same Sofnolime 797 CO2 Absorbent 8-12 Mesh Granules, Non-Indicating (44 lb | 20 kg) that are found online for $150/single keg?

I am working to the bottom of one and have another unopened but this sounds like a good deal

Sofnolime 797.

Thanks I was asking that to confirm mesh size, non-indicating, and keg weight. As well as to thumbs up your good deal

yes yes and yes.

Ok thanks I am interested given they have a stated shelf life of 5 years. That is if nobody else needs them soon, like by the end of week/month. I don't want to be a hoarder since I still have a full unopened keg

I know at least a year you can easily run past expiration

To be clear, this is expired sorb. It's already over five years old. Sure it's probably still ok, but if you buy it I'd use it quickly.

Or just buy a fresh keg for about $180 shipped.

McGlencoe wrote: ↑Tue Aug 11, 2020 9:11 pm What's the date on the kegs Jeff?

Jeff Pack wrote: ↑Wed Aug 12, 2020 6:39 am its right in the post

Stuff lasts for well past expiration. I'm still using 2019 stuff.

July of 2020?

Selling expired sorb? It may last way past expired, but it seems like a big liability for the seller.

if you think it matters dont buy it. I've been using 2019, I'm not dead. Its been kept temp controlled, low humidity, shaded area.

If you are worried about risk, I'm sure if we compared types of dives done, if I'm using even slightly older Sorb for the dives I do....

BTW, theres whole threads on expired sorb on RBW and elsewhere. I wouldnt even think twice about using it.

http://www.rebreatherworld.com/showthre ... nolime-797

Jeff Pack wrote: ↑Wed Aug 12, 2020 10:13 pm if you think it matters dont buy it. I've been using 2019, I'm not dead. Its been kept temp controlled, low humidity, shaded area.

If you are worried about risk, I'm sure if we compared types of dives done, if I'm using even slightly older Sorb for the dives I do....

I've seen the expired sorb threads before and if you want to use it for your own use, go for it.

I was only talking the liability to the seller if something goes wrong for the buyer.

You want to compare dives? Do I need to get a tape measure out?

It'd be a shame for good material to go to waste if the hydrate is still functionally intact. More of a shame though if misused with poor outcome, yes. Sounds like a highly advanced consideration for someone who is confident in their abilities to judge risks, efficacy and appropriate use circumstances.

Perhaps even better would be some kind of functional and compositional assay, but that would require opening it and the analytical expertise/techniques/instruments to test in comparison to brand new sorb. It's actually not that difficult to do that kind of analytical chemistry, though I do not personally have a home lab in which to do so. An analytical balance, a small drying oven, a ppm CO2 analyzer, some fittings and a calibration gas (e.g. 1000 ppm CO2) for example could provide useful data.

eh.haole wrote: ↑Thu Aug 13, 2020 7:43 am It'd be a shame for good material to go to waste if the hydrate is still functionally intact. More of a shame though if misused with poor outcome, yes. Sounds like highly advanced consideration for someone who is confident in their abilities to judge risks, efficacy and appropriate use circumstances.

How do you misuse sorb?(other than run it past manufacturers time rating). Appropriate use circumstances? I regularly dive well past 200ft. Current and non current dives. If you dive a CCR, you are already well into a higher risk group.

In either case, If I decide to keep diving, I'll use it without a thought. I'm still mulling that over.

For example if I suspected a packed canister of being potentially stale, I might be more conservative on the duration and conditions of use, such as the type of dive, and/or dump it more often. Presumably a margin of variation is acceptable for shallower shore dives with low workload and low likelihood of vigorous currents etc. Others' approaches might differ. A BOV might be useful also. (Mine's still being shipped.) One could also use the "old" kegs for presumed low-consequence dives, and "new" kegs for more serious ones.

Having not yet ever experienced or tested anything close to hypercapnia or breakthrough on CCR, I can not personally guarantee that I would keenly sense when a canister is close to being functionally exhausted. I simply haven't done that experiment. Others have, e.g. Simon Mitchell's teams in controlled clinical environments.

Yes it's easy to hold your breath, freedive, or breathe through an empty canister or a closed bag on the surface to get a feel for CO2 buildup under those conditions. I've done those. But that may or may not feel the same as a canister slowly breaking through while diving. I have no personal data for comparison.

What I do know is that with fresh sorb, up to six hours on a 2.5kg canister has been fine so far, but the diving is all calm/low exertion with an overall rate of O2 L/min consumption below 1.5. Those numbers are highly personal. I only weigh 75kg. Taking a wild guess that older sorb is 50% as good, one could cut that down to a three hour max, but there would be no analytical basis for that guess.

We do hear about fellows occasionally going past the line of no return and then not being able to bail out, such as this guy, who claims to have known what was wrong, and yet still didn't act appropriately. Poor buoyancy, excess exertion, etc certainly didn't help him either
https://www.youtube.com/watch?v=Abmy9YOAl1w

If you are pushing a 5.5 pd scrubber 6 hours in our colder waters, you are far braver than me. Our Megs are rated at 3.5 hours, I push to 4, maybe 4.5 if all scooter dives.

eh.haole wrote: ↑Thu Aug 13, 2020 8:24 am
We do hear about fellows occasionally going past the line of no return and then not being able to bail out, such as this guy, who claims to have known what was wrong, and yet still didn't act appropriately. Poor buoyancy, excess exertion, etc certainly didn't help him either
https://www.youtube.com/watch?v=Abmy9YOAl1w

reusing and picking out the clumps of sorb. didnt help much either.

Jeff Pack wrote: ↑Thu Aug 13, 2020 8:56 am If you are pushing a 5.5 pd scrubber 6 hours in our colder waters, you are a greater risk taker than me. Our Megs are rated at 3.5 hours, I push to 4, maybe 4.5 if all scooter dives.

My understanding is that before CE, cave divers were going with a rough "one hour per pound" rule of thumb, which could and did result in CO2 hits under occasionally extraordinary(?) circumstances presumably involving mispacking, material issues, or exertion. Anyone intelligent would toss out used sorb and pack anew before any properly serious dive, which is what I tend to do for current-sensitive sites and deco dives too.

The stated/nominal capacity of 100% functioning 797 sorb is 150 L CO2/kg, which for a 2.5kg scrubber is 375 L CO2. Converted to "O2 equivalents" at a factor of 1/0.8 gives ~470 L of oxygen consumption. At an O2 consumption rate of 1 to 2 L/min, that would be roughly four to eight hours.

I also find it highly unlikely that Megs and JJs etc were -designed- to have a dramatically lower canister capacity than their oxygen capacity. 150 bar (200 minus a reserve of 50) of a 3L oxygen cylinder is 450 litres available, which in theory lasts 5 to 7.5 hours at 1.5 to 1 L/min of consumption. I don't think that it's a coincidence that this lines up almost perfectly with the theoretical scrubber capacity, as above. I assume that's where the "fill your o2 & change your scrubber" idea came from.

But yeah we all are taught and officially work around the CE 3 hour standards because that's what standards are for, and once in a while someone gets hit under three hours.

Just to nerd out about canisters a bit further,

In this paper, they put Simon Mitchell on an exercise bike, generating a standardized 2.0 L/min of CO2, with a breathing rate of 44 L/min (22 breaths per minute--quite high for sustained breathing). His 2.64kg (avg.) of sofnolime lasted 202 minutes (avg.) before breakthrough, as defined by a ppCO2 of 1 kPa = 0.01 bar = 10,000 ppm. 5,000 ppm is the OSHA limit and 20,000 ppm is assumed to be the threshold for effects on breathing reflexes.

According to the nominal 150 L CO2/kg capacity of 797, these canisters would have been predicted to last 198 minutes (150 L/kg * 2.64 kg / 2L/min). That comes out uncannily close to the real result.

2 L/min CO2 however is a fairly high rate of metabolism. This would correspond to an oxygen consumption rate of about 2.5 L/min, which is well above the rate at which most people consume oxygen during relaxed, slow, calm diving with proper trim and buoyancy, which is more like 1 to 1.5 L/min.

Alternatively, if the sorb were only 50% active--completely hypothetical number here--then it might have lasted only 99 minutes at Mitchell's high workload, barring any more complex aggregate effects of sorb columns with varying fractional activities.

I've also 2 kegs expiring 7/21 for sale

Unopened?

Price?

Unopened, make me an offer

Geez leave Jeff alone... Either buy it or don't buy it but I'm pretty sure your cells in your rebreather will tell you when you're running out of good breathable air