CO2 hit documented

CaptnJack · Post by **CaptnJack** » Wed Nov 28, 2007 1:01 pm

This has been posted elsewhere but I don't think everyone here reads those boards. There are a couple of very long weird pauses in here; keep watching. There are credits at the true end.

http://www.hse.gov.uk/diving/video/co2video.htm

The diver's continued compromised mental state even after bailing out is pretty scary.

Joshua Smith · Post by **Joshua Smith** » Wed Nov 28, 2007 1:50 pm

I saw this, and it made me sit up straight and pay attention. Mel specifically mentioned the incredibally ill advised scrubber packing practice that caused this during our class. I remember wondering who in the hell would be dumb or crazy enough to do that- this vid should be required viewing for any CCR class- really scary.

CaptnJack · Post by **CaptnJack** » Wed Nov 28, 2007 3:58 pm

Yeah no kidding. Staying very very far away from CO2 breakthru seems like a duh! habit.

How much does sorb cost anyway? I know different units take slightly different types/sizes/volumes but for a typical packing?

Joshua Smith · Post by **Joshua Smith** » Wed Nov 28, 2007 4:11 pm

CaptnJack wrote:Yeah no kidding. Staying very very far away from CO2 breakthru seems like a duh! habit.

How much does sorb cost anyway? I know different units take slightly different types/sizes/volumes but for a typical packing?

I'm not quite clear on that yet- I haven't started buying it yet, so I'll be doing the math pretty soon. It's not cheap, per 5 gallon bucket, but you can get a lot of dives out of one of them. I've heard prices from 1-200 bucks for a 5 gallon container, I believe a Meg scrubber can be filled 5 times from one bucket, and you get 3 hours out of a scrubber....so cheapskates would be tempted to "recycle" their "unused" scrubber material, I'm sure. I call that kind of thing "Dancing with Darwin."

CaptnJack · Post by **CaptnJack** » Wed Nov 28, 2007 4:22 pm

So $20 to $40 or so depending on unit. Good info. Obviously a Drager Ray has a relatively tiny scrubber vs. some much larger units.

I don't totally understand why they were mixing up the partially used sorb. Using the old as a "spacer" with some new cause the dive wasn't supposed to be a full scrubbers worth or what?? Or just taking partially used out and mixing it with itself before dive 2 for what purpose??

The video wasn't clear to me on these issues.

Bailing out on a 3L bottle (they were unclear on the fill pressure) seems totally inadequate. If it were a 3000psi clyinder thats = 13cf. He just smoked through that tiny volume huffing and puffing almost before leaving the bottom.

Joshua Smith · Post by **Joshua Smith** » Wed Nov 28, 2007 4:40 pm

Yeah, 20-40$ per sounds like it's in the ballpark. The specific practice I was warned against was this: After 3 hours, the scrubber material on the recieving end is "clumpy", but near the top, it looks unused- some divers used to- I hope to hell they don't do this any more- pour the "fresher looking" stuff out, set it aside, and reuse it- but "clumpiness" isn't a reliable indicator for c02 retention, I'm told, and, well- why risk it?
I thought that was what they were talking about the first time I watched it, but you're right- they were smashing it back up and diving it again, according to the video. Maybe they thought that would chase the C02 demons out of it? I dunno, doesn't make any sense to me, and I don't even have an advanced degree in theoretical astro-chemistry. The rumors over on RB world are that the "instructor" who taught this technique has been banished from the tribe, and no longer teaches- I wonder if any of his students died as a result of this?

3L= 13 cf? (I'm not too swift w/ metric volume conversions) That seems.......uh.......I keep deleting words here.......inadequate. I'm using a 40cf right now, myself.

CaptnJack · Post by **CaptnJack** » Wed Nov 28, 2007 5:20 pm

"Out CO2 out...."

Ok good to go! Lol

Ok now I understand a little of how the "reuse the good stuff" attitude may have arisen. Thanks, obviously a dumb idea.

3L = the cylinders water volume, our 13cf cylinders are ~2.75L water volume.

The ones used over in the UK may have been slightly higher than 3000psi cylinders so delivering max 15-18cf or something like that (or lower psi although that seems unlikely). Still awfully small.

John Rawlings · Post by **John Rawlings** » Wed Nov 28, 2007 6:06 pm

I just watched the video....amazing stuff! One of my Brit buddies, Simon Pridmore, is one of the people interviewed. If Simon is involved in it, it's legitimate and serious.

- John

Seth T. · Post by **Seth T.** » Wed Nov 28, 2007 8:42 pm

And yet another reason why we dive with buddies!

Pez7378 · Post by **Pez7378** » Wed Nov 28, 2007 9:31 pm

Seth T. wrote:And yet another reason why we dive with buddies!

Oh I thought this was why........... http://www.nwdiveclub.com/viewtopic.php?t=3376

Solitude Diver · Post by **Solitude Diver** » Wed Nov 28, 2007 9:45 pm

Holy s_ _t! I can’t believe I just heard all of that. Who in the h_ _L teaches people to reuse, and repack their scrubbers, AND also to use a 19 cft cylinder for rebreather bailout? I think they were not throwing away the clumps but actually breaking them up for re-use. And did the video mention that this is common practice, or is that just my poor memory and recollection?

Someone should investigate the instructor(s).

I like the idea that people are using this video in classes.

Solitude Diver · Post by **Solitude Diver** » Wed Nov 28, 2007 9:52 pm

I've found that (at least as far as the Evolution goes) you can actually get the media for about $3 per lb if you shop around. It only takes about 4 lbs to fill the unit (only $12 per fill), and that is good for 2-4 hrs/dives (depending on depth and how hard you are working it).

Hardly seems worth the effort to try to reuse/repack it to save a couple of dollars and risk your life.

CaptnJack · Post by **CaptnJack** » Wed Nov 28, 2007 9:58 pm

Seth T. wrote:And yet another reason why we dive with buddies!

Although the commentary suggests that the buddies took awhile to understand that the subject was in bad shape. OC or RB I want buddies who are a bit more decisive and "take charge" if I were mentally compromised like that.

Mike Barnette ("Barney" on TDS) almost died due to toluene contamination on a cave dive ~3 yrs ago. That volatile just made him totally looped out of his gourd. Fortunately he survived to document the incident, but note that he never did quite understand what was going on or chose to exit on his buddy's gas. He just didn't have the metal acuity to put everything together.
http://thedecostop.com/forums/showthread.php?t=8069

Much like the CO2 hit documented in the video.

Joshua Smith · Post by **Joshua Smith** » Wed Nov 28, 2007 10:11 pm

agreed- his buddies just sat there and waited for him to make the next move. If a CCR diver bails out to OC, it's time to end the dive, "right now." Everybody should have been moving towards the surface immediately at that point, respcting any deco obligations, of course.

CaptnJack · Post by **CaptnJack** » Wed Nov 28, 2007 10:46 pm

Yeah ya gotta be more aware when something is "not normal" and take action not just watch.

HydroGirl · Post by **HydroGirl** » Thu Nov 29, 2007 7:37 am

WOW, great video!
This is not new to the rebreather divers. Years ago there was a handful of injured military divers (not in the US). They were told to pick the blue color CO2 scrubber out of a Drager Dolphin and re use, but at the time not all the granules were color changing.

lamont · Post by **lamont** » Thu Nov 29, 2007 9:30 am

CaptnJack wrote: I don't totally understand why they were mixing up the partially used sorb. Using the old as a "spacer" with some new cause the dive wasn't supposed to be a full scrubbers worth or what?? Or just taking partially used out and mixing it with itself before dive 2 for what purpose??

The video wasn't clear to me on these issues.

My guess was that the idea was to use the old stuff as "spacer" and not pack a full canister -- but that they also went and mixed up the old stuff with the new. There seemed to be a point there about the old stuff mixed in with the new caused channelling and made it all less effective.

Dmitchell · Post by **Dmitchell** » Thu Nov 29, 2007 11:03 am

lamont wrote:
CaptnJack wrote: I don't totally understand why they were mixing up the partially used sorb. Using the old as a "spacer" with some new cause the dive wasn't supposed to be a full scrubbers worth or what?? Or just taking partially used out and mixing it with itself before dive 2 for what purpose??

The video wasn't clear to me on these issues.
My guess was that the idea was to use the old stuff as "spacer" and not pack a full canister -- but that they also went and mixed up the old stuff with the new. There seemed to be a point there about the old stuff mixed in with the new caused channelling and made it all less effective.

The reasons why they were probably doing this wasn't as a space but more to "in theory" maximize the economics.

If you have a scrubber that should last 3 hours and you do one dive on it then decide that tomorrow you will do several dives, you will either have to dump the scrubber and "waste 2 hours" or they were thinking that they could save the 2 hours worth of scrubber in a sealed container, refill with fresh for the next day and use the old scrubber material on another day.

It's a dumb idea and they should have known better. You spend time properly packing a scrubber so that it doesn't channel. Mess with it and you risk channeling.

In the big scheme of thing, scrubber is cheap and trying to save $5.00 worth of scrubber can get you killed.

44lb kegs of Sofnolime are about $100, the KISS uses ~6lbs per fill and that's basically good for 3 hours. So that's about $14 per fill ~$5.00 per hour. It's cheaper than Nitrox.

Dave

CaptnJack · Post by **CaptnJack** » Thu Nov 29, 2007 11:25 am

Thanks Dave, I understand the "logic" now.

texdiveguy · Post by **texdiveguy** » Thu Nov 29, 2007 12:44 pm

The reasons why they were probably doing this wasn't as a space but more to "in theory" maximize the economics.

In the big scheme of thing, scrubber is cheap and trying to save $5.00 worth of scrubber can get you killed.

It's cheaper than Nitrox.

Dave

You would think that they would realize this....but people do stupid stuff.

scubagrunt · Post by **scubagrunt** » Wed Dec 05, 2007 11:03 pm

Nailer99 wrote:Yeah, 20-40$ per sounds like it's in the ballpark.
3L= 13 cf? (I'm not too swift w/ metric volume conversions) That seems.......uh.......I keep deleting words here.......inadequate. I'm using a 40cf right now, myself.

Hi Guys
A 3L is around a 19 ft3 tanks size. Sorb is around $100 for 40 pounds, the standard meg scrubber takes 6 pounds so just over 6 fills per bucket, so a fill is under $16 and that will last 3 hours, for a hourly rate on sorb of around $5.5. pretty cheap for an hour at any depth. of course you have to add in a O2 fill say $5 for 5 hours, and a Trimix fill of say $15 for 5 hours (or so depends on depth) which brings a trimix dive cost to around $10 and hour!!!