Northwest Dive Club

My other CCR thread accidentally got deleted, whoopsie

1) I have been doing a bunch of reading and one thing which is bugging me is scrubber duration. It seem like its so completely overkilled (workload or water temp wise) to be essentially useless. Wouldn't 5.5 or 6lbs of scrubber basically have the same reactive ability (at any given temp) and basically last the same time for a given workload? I am not a navy swimmer here, so some mil-spec test reporting 6lbs of scrubber lasting 2.5 hrs at 45F is not helping me gauge "my" scrubber duration. I know people doing 4+ hrs on that scrubber so that's comforting, but still, why do useless testing that does not approximate actual diving? Grrr

2) Is anyone around here diving a KISS Orca spirit LTE? Or have one in a shop I could look at in person?

Hey Richard.

In my experience, scrubber duration is really hard to gauge because its very much tied to your own specific physiology as well as your CCR canister design, your specific packing variances and then of course temperature and humidity for your specific dive. ALL of these are so freegin variable that its impossible for a manufacturer to rate a CCR's scrubber duration to you personally and your diving.

the tests they have done in the labs with machines, are as you alluded to, generally waaaay overkill and about 3x more CO2 than what you and I would ever be able to produce and makes those scrubber duration limits so conservative that its almost impossible for any human to reach it.

I've taken my CCR and very slowly and steadily logged very small increments on the 3 hour published scrubber durations and have empirically found that with normal diving I can easily push my scrubber to 4 hours very comfortably without personally feeling too worried about it.

I have not pushed it far beyond that since it requires me to remove the canister and seal it in a zip-lock bag in order to get 4+ hours duration over the course of a few days of diving. This probably also helps to pro-long the time since it gives the CCR plumbing a chance to dry out while keeping the absorbent somewhat moist when sealed.

That said, Im not comfortable to do a bigger dives on a canister thats already been used for an hour or two or pushing the limits.. I will re-pack a canister for bigger dives and stay within the limits and then save the remaining time left on it for weekly fun dives when possible by storing entire canister in sealed zip-lock bag. But bio-thermally speaking, 3 hours on a PNW tec dive is for sure more than I care to do in a single dive anyways..

Until you get a CO2 monitor that can reliably detect break troughs, it will be super hard to decide where to draw the line without being your own "test subject" and empirically work your way up to where you are personally comfortable with scrubber duration.

But suffice to say, the publushed numbers are super conservative.. The RB80 guys have pushed those scrubbers to like 10 hours..

Is there any merit to the concept that 5.5lbs of scrubber should last 4 hours plus? (even though "testing" by some superhuman robot its "2 hrs")

I am likening the Kiss Orca spirit lte for a multitude of reasons but the scrubber is only "rated" at 2 hrs in 45F. And I don't know anyone diving it locally. I don't want to do 4x 1 hr dives, I want to do 1x 4hr dive (yes locally, yes in cold water, yes with suit heat)

FYI in case you are wondering:
its light enough to travel with (FL or MX),
modular for packing into BC caves,
its manual,
has a unique counterlung which is seemingly perfectly positioned for cave diving (along the rib cage, same depth as your actual lungs yet underneath and protected by sidemounted dil/bailout bottles)
6" thick or so, it does not sit up high on the back despite the canisters being backmounted,
is perfectly happy with exclusively offboard dil/bailout sidemounted,
lastly I can get training by actual cave divers in FL,
happy with one budget hardwired ppO2 gauge and one shearwater computer monitor,
can easily add a HUD later if I want one,
its not ridiculously expensive.

I am looking into whether the LTE can accept the stainless steel covers that Kiss makes for the Orca.

for my Meg, I use 4 hours as cut off point in colder water. Most I know use that. My gem with user packable scrubber, used same numbers.

If scootering in cold water(like 2x2.5 hr scooter dives for example), or extended deco from a longer/deeper dive (single dive) I'd push to 5 because of much lower CO2 production(although I dont know I could actually last 5 hours in cold water, 4 was bad enough).

With a keen eye, you can often see the reaction front within the scrubber material(and I dont mean indicating sofnolime). Alternatively, how the scrubber material dumps out of the canister is another indication of scrubber usage.

But overall, 4 hours is a comfy number for cold water diving. Still leaves you "some" reserve...

Richard, go talk to Craig Willemsen at SilentWorld in Bellevue. He is a super nice guy and has been diving KISS breathers for a very long time.

He had an regular Spirit in his store with that "rib cage" cover when I was there last and he has been diving it a few times. AFAIK.

I bet you he would be able to give you all kinds of good information on it.

The one thing I really dont like about it is the OPV and ADV thats ontop of the canister.. you would very easily bump and damage that in caves.. even the JJ gets a beating in the caves on the canister "lip" and people install metal covers over it

One nice thing is it looks like its has 2 seperate canisters, so you cold do the same thing they do on the rEVO and swap them and get longer duration on multi dives..

2 hours certainly is not a lot for a 5.5 scrubber.. I think the JJ is 3 hours on 5.5lb and really dont think 4 hours is pushing it too much, like Jeff said, thats about the norm for most people on 5.5's and kinda where they draw the line.

Yes being able to add the metal case is pretty much a requirement for me to take it cave diving. The heads have too much important stuff to go wacking into the ceiling.

I emailed Craig about visiting to see his similar unit. Perhaps he has some first hand knowledge of "actual" scrubber durations? I know the KISS units take a specific sodalime, maybe its less reactive than the 5.5 lbs used in other scrubbers of comparable size? Or perhaps its all just voodoo and 5.5lb = 4 hours or more regardless of scrubber design/layout (the chemist in me suspects this is roughly true).

Yeah if it uses the bigger 408 mesh granules, you will get less time and theoretically it has better WOB..

Although, I checked and it uses the exact same 812 Mesh than what the JJ and rEVO and Meg uses, so it might be scrubber design.

Im sure Craig would be able to give you some first hand knowledge of the units.

Mike and a few guys like running the bigger mesh stuff. I have to no clue why. Even on my prototype sidekick, I was the first person using 812 in it. The only real issue was the filter screens, as the dust from 812 would blow right threw'm. So I replaced the screens with ones from a MEG.

Unless the new units are out of Mikes design norm, they are simple axial scrubbers, no magic to them. OTOH, I know nothing about the new units. You also might try and ping Doug Ebersole or Rob Neto for answers. I know Doug runs the new RB's, not sure Rob does (I know he runs the sidekicks). They can contact Mike on anything they dont know.

Koos, where did you see the mesh size? Its not reported in the manual as far as I can see.
http://www.kissrebreathers.com/pdf/Orca ... %20R.3.pdf

Diversupplyinc is their recommended supplier for sordasorbHP and this is the only product they sell which seems to match
http://www.diverssupplyinc.net/browse.cfm/4,1467.html

Mesh is "4-8"?

CaptnJack wrote: Mesh is "4-8"?

Yeah. After forming the soda lime granules, they will pass through a mesh sieve of size 4 but be caught by a size 8. http://www.sigmaaldrich.com/chemistry/s ... rsion.html has details of mesh size

Most breathers will run with either, but it depends on the porous screens they use in the scrubber. The Work of Breathing testing is usually done with a preferred size, too. I have run both in the Evolution and Inspiration, for example, depending on what I had around, but it's generally spec'd as 8-12 mesh.

Rough rule of thumb is a kilogram of scrubber an hour. Of course, that's the breathing machine rate...as noted, it's super high.

I have pushed the Evolution (rated 2 hours) to 4+ on a regular basis. On the other hand, it has a temp stick in it, which helps, and it depends on the dive situation. Temp stick methods, like the rEvo and the Inspiration/Evolution are more reliable gauges of scrubber life than CO2 sensors, if you understand the chemistry of the reaction front and how the gradients work. Scrubbers are just plug-flow reactors, so it's pretty easy, with math no more complicated than basic calculus, to work out how things proceed. (Of course, being a chemical engineer by training didn't hurt...)

There's a lot of BS floating around out there about scrubber material from people who lack the science education to back it up. BS like "prebreathe to activate your scrubber." Or crazy in-between dive-day storage rituals in zip locs, to maintain moisture and prevent use (unnecessary for any reasonable length of time...you can go months with a packed cartridge sitting in the storage room at reasonable conditions just fine.) Ask chemists, or ask the manufacturers who test with real breathing machines (Paul, Martin, Leon, etc). Beware the internet divers.

CaptnJack wrote:Koos, where did you see the mesh size? Its not reported in the manual as far as I can see.
http://www.kissrebreathers.com/pdf/Orca ... %20R.3.pdf

Diversupplyinc is their recommended supplier for sordasorbHP and this is the only product they sell which seems to match
http://www.diverssupplyinc.net/browse.cfm/4,1467.html

Mesh is "4-8"?

http://kissrebreathers.com/spirit-ccr.html
scroll all the way down to the specs.

Everyone I know buys the Molecular 797 Grade (812 Mesh) Sofnolime from AddHelium.com. they are by far the cheapest with free shipping.

There's a whole lot of science out there regarding scrubber duration. It's one area that I'm super-duper conservative about. C02 scares the crap out of me. The meg axial, which I dive, is officially rated for 3 hours in cold water, but most guys I know will take it to 4, which is probably fine- but I never do. I've tossed scrubbers with 2 hours on them, just so that I can do a dive without worrying about it. The radials are pretty cool, and I'd probably buy one, if I had an extra grand lying around. But it's been a while since that happened. I guess what I'm saying is that I would take the manufacturer at their word when they tell you what scrubber duration is- they're the ones that are hooking them up to WOB machines and running the results through mass gas spectrum analyzers and such. I've heard lots of stories about guys using medical sorb, or pushing scrubber limits to double or more.......and it drives me crazy. Wow, you saved, like 30 bucks? High five.

It would make a whole lot more sense to me if they rated scrubbers by volume of O2 consumed at a given temp!!! Seriously you can't create CO2 out of nothing, O2 in, Co2 out.

I am looking into bigger units, I can't afford to buy twice...

Up here, my rMs gives me a little over 3 hours until I need to change out my top canister. I only went through it once, but I don't remember exactly how much time I had on the second canister. When I was in Bonaire, I was doing 4 hours before I dumped the scrubber, mainly because I didn't want to change out canisters on-site. The rMs was giving me at least an hour more. For me, I use the rMs more for ensuring I am not getting CO2 break through on the first scrubber, than I do for stretching it out.

If you are worried about protecting your counter lungs, I'm not sure you could get much more protected than a rEvo.

fishb0y wrote:Up here, my rMs gives me a little over 3 hours until I need to change out my top canister. I only went through it once, but I don't remember exactly how much time I had on the second canister. When I was in Bonaire, I was doing 4 hours before I dumped the scrubber, mainly because I didn't want to change out canisters on-site. The rMs was giving me at least an hour more. For me, I use the rMs more for ensuring I am not getting CO2 break through on the first scrubber, than I do for stretching it out.

If you are worried about protecting your counter lungs, I'm not sure you could get much more protected than a rEvo.

I'm getting between 4 and 5 hours in Hawaii on the top can with the RMS. I'm also on a scooter every dive, so that plays into it as well.

I usually cycle when the top scrubber is showing around an hour left.

One scrubber on the rEvo holds 3 pounds of kitty litter.

RMS ain't cheap, unless you get a used one with a unit you buy. But there is no feeling in the world like seeing those green numbers giving you real time reaction information on the home screen of the petrel.

One of my temp probes went Tango Uniform last week and I've been kinda miserable without the RMS the last 3 dives I've done.

Yup, the rMs is not cheap. I was lucky enough to be grandfathered in on one of the first ones.

fishb0y wrote: If you are worried about protecting your counter lungs, I'm not sure you could get much more protected than a rEvo.

Sadly the revo is terrible on the bank account. And honestly the flood resistance leaves something to be desired too.

Yup, not cheap but I have seen a bunch of used ones pop up on Rebreatherworld.

Compared to other units, I think the flood resistance would be better with the enclosed lungs and bar over the top of the unit... Dewatering is another issue, but one you rarely need to use.

My I am more concerned with a CO2 hit, with the rEvo I feel is the best unit out there, that I am about flooding the loop.

Meg divers correct me if I'm wrong, but you would end up using most of your dil trying to clear the loop.

I found a revo III mini that I'd actually be interested in, if it wasn't $9K, used.

fishb0y wrote: Meg divers correct me if I'm wrong, but you would end up using most of your dil trying to clear the loop.

Maybe with a little hp23 dil bottle. A lot less likely an issue with 240+cf of dil...

CaptnJack wrote:I found a revo III mini that I'd actually be interested in, if it wasn't $9K, used.

fishb0y wrote: Meg divers correct me if I'm wrong, but you would end up using most of your dil trying to clear the loop.

Maybe with a little hp23 dil bottle. A lot less likely an issue with 240+cf of dil...

9k, sounds like it's fully loaded with RMS, extras and possibly titanium. At that price, it will probably sit a while.

If I can ask, what's your price ceiling.

pensacoladiver wrote:

CaptnJack wrote:I found a revo III mini that I'd actually be interested in, if it wasn't $9K, used.

fishb0y wrote: Meg divers correct me if I'm wrong, but you would end up using most of your dil trying to clear the loop.

Maybe with a little hp23 dil bottle. A lot less likely an issue with 240+cf of dil...

9k, sounds like it's fully loaded with RMS, extras and possibly titanium. At that price, it will probably sit a while.

If I can ask, what's your price ceiling.

Total with MOD1 training about 8k

You probably won't find rms and training for that.

Hybrid plus training, more than likely if you look around.

Manual plus training, absolutely, with some cash even left over.

Have you given any thought to one of these for your side mount style? One of my UK cave diving friends just got one and is doing the training. He got it for the sumps that include loads of walking, but are not terribly deep.

https://vimeo.com/channels/tritonccr

pensacoladiver wrote: Manual plus training, absolutely, with some cash even left over.

Manual is what I'm looking at. I don't see myself below about 210-220ft and many of the likely systems are really hard on gear so electronics are to be avoided. Something about cold water and gloves just beats everything up 10x more than a FL or MX dive would.

ljjames wrote:Have you given any thought to one of these for your side mount style? One of my UK cave diving friends just got one and is doing the training. He got it for the sumps that include loads of walking, but are not terribly deep.

https://vimeo.com/channels/tritonccr

I have to say that chest mounted counterlung (singular?) is crazy!!

Looks a bit too specialized for me honestly, and looking at RBW the scrubber is apparently good for 150mins which is far too short. There's the issue of training on it too. Neat looking unit, reminds me of a WW2 O2 rebreather. Just not something I would jump into though.

If you check on Rebreather World and CCR Explorer's you can find some good deals on a used manual CCR in the $4500 range.

The big difference in a 8-12 and 4-8 mesh is the 4-8 has much less WOB. But it also has much less surface area for the reaction so does not preform as well as the finer mesh materials. First time I tried 408 (4-8 mesh) i thought my unit was F'ed up and maybe flooding or something. Their was no resistance that I was used to so I was a little startled at first. After rolling around listening and feeling for water or bubbles figured out all was fine.

The big difference of flood with the rEvo and a canister style CCR is most canisters can only take a cup to a cup and a half of water and they are absolutely useless and unable to breath. Some as little as a half cup of water. A rEvo's exhale counterlung can hold a gallon+ and you can stay on the unit. Keep in mind you will have to maintain a slightly head up attitude in the water to keep it in the bottom of the counterlung and away from the sorb. you can with some in-water acrobatics dewater a rEvo as well. Buy rolling up and purging the water out the OPV same as a Meg. You have to do a slow handstand moving the water to the top right of the unit to the OPV and Dill Flush it. not that difficult at all to do but defiantly not as easy as a Meg.