Northwest Dive Club

trust me


http://youtube.com/watch?v=iVgD2X0Iwws&feature=related

Hey, welcome to the board! How about introducing yourself!

Yes, that is one of the cool things about the REVO is the scrubber.


Dave

I was on Bandito this past Sunday with Nailer99 and a few others from this board. Good group of divers,,,,,I believe a good time was had by all... Too bad Nailer wouldn't trade me his Meg for my dolphin for a dive : ))). That megladon Rocks

Hey, welcome to our site, Warren! Good time last weekend- let's get together and dive soon!

jixxer1 wrote:trust me


http://youtube.com/watch?v=iVgD2X0Iwws&feature=related

I've been looking at those Revos, actually- I think they're pretty cool, and I like the "dual scrubber" idea.

(But I looooooove my Meg! )

so why would you take the bottom scrubber and put in the top slot??

Gas flows through the upper scrubber first, then into the lower scrubber- the theory is that the upper scrubber is used up after 2(I think) hours, but the lower scrubber is still unused- so you can swap them, replacing the upper with the lower, and placing a fresh one in the lower slot- it's a redundant feature that I think might be a really good idea, but time will tell.

More info here

Hey! Nice explanation and it actually made sense..especially after watching videos of folks who don't do right by their scrubbers..hm..

Welcome, Warren! Glad to see you here!

Jackie

Nailer99 wrote:Gas flows through the upper scrubber first, then into the lower scrubber- the theory is that the upper scrubber is used up after 2(I think) hours, but the lower scrubber is still unused- so you can swap them, replacing the upper with the lower, and placing a fresh one in the lower slot- it's a redundant feature that I think might be a really good idea, but time will tell.

More info here

Sewer rats may taste like pumpkin pie, but I won't know cause I don't eat the filthy... ya know.
Still on the fence about the logic behind the design. I would like to say different Strokes for different folks, but that might spark a fire. ya know.

Like it or not, it's been well received by the rebreather diving community worldwide. The Revo is a neat little unit and they have a bunch of good things going for them. I suspect that they are about to really take off.

Now if they can just get rid of that hideous yellow box..... :rr:


Dave

to me the scrubber design is an interesting approach. I think there could be merit to the idea of more than doubling your estimation of the most scrubber you are likely to need yet avoid having to throw out the unused portion each time as you do in every other design, as long as you stay within the calculated range. It seems like you can err more on the conservative without feeling so wasteful. though I guess the folks who are envelope pusher will just push it that much further, obviously if you over shoot, you only short your next dive and increase the chance of a hit then since you would have eaten in to the back up. My guess is that if used as intended the design adds a buffer. And it would seem logical that for the unplanned instance of ending up on a current treadmill or any hyperventilation spiral where the dwell time drops exponentially and co2 is more likely to make it past the reactant front, deeper into the scrubber stack, that having the extra capacity may just help reduce the likelihood of co2 breaking through to the inhale side of the loop. the little bit that would make it past the first scrubber in such rare instances would likely not effect the overall capacity of the second scrubber much. of course it's all a matter of degree though. Well just my gist of the idea behind this approach anyway.

cutting the scrubber in two and orienting them side by side instead of in a column has resulted in a very slim design and i'm very curious if that configuration has increased the WOB since there are more sharp turns in the flow circuit.

As with all things rebreather, there are lots of nuances to debate.

I need to look at it with a more serious face on. The Sport KISS has a dual chamber design and I like many others were quick to consider it the new and improved method to co2 removal and breakthrough prevention. I sold a few units, each has been replaced. These days I like more than just 5 to 50 units in circulation with considerable usage accomplishing creditable limits before I say it is amicable for the masses. There is no doubt the rEvo is on it's way to becoming a main stream RB, but my serious face says time will tell.

Matt (or someone knowledgable) can you explain more about your trepidations around dual chambers?

Assuming you ignore they so-so idea for reusing media (to some extent) and change both canisters simulataneously, what are the pluses and minues of dual chambers outside that??

Thanks
Richard

ps I have to say the slim design and backmounted counterlungs are more appealing to my sensibilties.

mattwave wrote:

Nailer99 wrote:Gas flows through the upper scrubber first, then into the lower scrubber- the theory is that the upper scrubber is used up after 2(I think) hours, but the lower scrubber is still unused- so you can swap them, replacing the upper with the lower, and placing a fresh one in the lower slot- it's a redundant feature that I think might be a really good idea, but time will tell.

More info here

Sewer rats may taste like pumpkin pie, but I won't know cause I don't eat the filthy... ya know.
Still on the fence about the logic behind the design. I would like to say different Strokes for different folks, but that might spark a fire. ya know.

Yeah, well, I didn't buy one, but the design is intriguing- like you say, time will tell with this one.

the manufacturer's latest numbers suggest that there are over 100 rEVO's in use.

mattwave wrote:I need to look at it with a more serious face on. The Sport KISS has a dual chamber design and I like many others were quick to consider it the new and improved method to co2 removal and breakthrough prevention. I sold a few units, each has been replaced. These days I like more than just 5 to 50 units in circulation with considerable usage accomplishing creditable limits before I say it is amicable for the masses. There is no doubt the rEvo is on it's way to becoming a main stream RB, but my serious face says time will tell.

CaptnJack wrote:Matt (or someone knowledgable) can you explain more about your trepidations around dual chambers?

Assuming you ignore they so-so idea for reusing media (to some extent) and change both canisters simulataneously, what are the pluses and minues of dual chambers outside that??

Thanks
Richard

ps I have to say the slim design and backmounted counterlungs are more appealing to my sensibilties.

Seems like at first glance it makes perfect sense, but let's say:

You over breathe your primary canister, consequently utilizing your secondary canister.
Now you don't have a 100% assurance that you have or have not over breathed your canister, you swap them and now you have a slightly or not so slightly used canister as you primary and an spent canister as your secondary.
I could be more inclined to always have at least one freshly packed canister, but if you were to call is truly a redundant system, you would need two freshly packed canisters, where I can see the merits.

For as popular and mainstream some say the rEvo is; I would like to see them in usage, and get a more touch and feel operation of the unit.

George are there any in this Seattle or PNW area?

mattwave wrote:
Seems like at first glance it makes perfect sense, but let's say:

You over breathe your primary canister, consequently utilizing your secondary canister.
Now you don't have a 100% assurance that you have or have not over breathed your canister, you swap them and now you have a slightly or not so slightly used canister as you primary and an spent canister as your secondary.
I could be more inclined to always have at least one freshly packed canister, but if you were to call is truly a redundant system, you would need two freshly packed canisters, where I can see the merits.

For as popular and mainstream some say the rEvo is; I would like to see them in usage, and get a more touch and feel operation of the unit.

George are there any in this Seattle or PNW area?

I guess I don't understand your logic here. When you swap, you are always putting in a fresh canister not switching the locations of the used ones. So your "secondary" is always fresh.

In addition, they are using a little more scrubber than most all the other common units out there and not really increasing the duration at all just getting better use of that top section that we all throw away knowing that it's still good.

The Revo full holds 2.8Kilos of Sorb compared to 2.5 on the inspo and meg, 2.1 on the Evo and 2.7 on the Classic Kiss. Not a huge difference but still more.

I've heard that you will be seeing some units in the PNW real soon.

Dave

Dmitchell wrote:

I guess I don't understand your logic here. When you swap, you are always putting in a fresh canister not switching the locations of the used ones. So your "secondary" is always fresh.

In addition, they are using a little more scrubber than most all the other common units out there and not really increasing the duration at all just getting better use of that top section that we all throw away knowing that it's still good.

The Revo full holds 2.8Kilos of Sorb compared to 2.5 on the inspo and meg, 2.1 on the Evo and 2.7 on the Classic Kiss. Not a huge difference but still more.

I've heard that you will be seeing some units in the PNW real soon.

Dave[/quote]

Ok maybe this will help: I ask these 3 questions:

1: Does your exhalation breath pass through the secondary scrubber?

2: Should there be an amount of residual co2 in the gas leaving the primary canister even if it is a fresh pack?

3: Is there any method or gauge to determine if in the fact the secondary canister has been activated?

If the answer is yes to either or both of the first two questions or no to the third, maybe my logic makes more sense?

For the record I have no experience with the rEvo CCR and have no intentions of discrediting it's design, just trying to wrap my head around this new method to extending scrubber life. I do have one more thought - which of the 5 RB Certifying agencies in the US endorse this method of canister swapping?
IANTD?
TDI?
ANDI?
GUE?
NAUI-Tec?

1. yes
2. yes
3. no, it's expected to be activated but it's not completly used.

If you only put one can in, it has a 2 hr duration so put in a second and you only get 3 hours.

Dive 2 hours change the used scrubber and rotate. Plan to dive 3 hours use 2 new scrubbers.

The point is that they aren't marketing it as a redundant system. The goal was to make a unit that has and efficient scrupper, BMCL and a good WOB. By using the setup he has, he has done a good job of that. Reports are that it breathes as well as or better than the SDS units, close to the Meg and better than the rest.

The other gain by using this system is simplicity and size. By not having a can, it's pretty darn small and I guess the teardown and rebuild is super easy.

Read the manual:
http://www.revo-rebreathers.com/Manual% ... 022007.pdf

Dave

Likewise, I don't own one and am not buying one anytime soon.

Radomski is an instuctor for it so ANDI must be on board.

My bottom line is at this level, training agencies issue cards, Manufacturers design rebreathers. The agencies don't need to be on board.

Dave

After watching the CO2 hit video last week, I'd be disinclined to swap canisters. Just replace both after a few hours of diving and don't try to be cheap and stupid.

So removing that "non-benefit" are there any drawbacks to have two canisters? What's the negative issue on the Kiss, WOB? Sounds like they have solved that (whether its a big deal or not is another matter).

Great discussion. I for one like the fact that there are new manufacturers getting into the market with new models. Competition = innovation. Of course, it also means some people get hurt or dead from using unproven technology and such, but I think a dumb person can die on a time-tested machine and a smart person (choosing wisely) can do many, many dives on newer models that have yet to see significant mileage.

of course it's all a matter of degree, as it's recommended to change out both scrubbers after each deep or high exertion dive. With deeper diving on any rebreather the denser gas causes the reactant front to spread out /go deeper down, or in this case across the stack becoming more difficult to predict remaining capacity. More co2 molecules pass by more scrubber granules without coming in direct contact with them since they are "shielded" or to say it another way, diluted, by a higher concentration of N/o2/HE and co2. for a given co2 molecule to get sequestered it takes more passes acrosss absorbent granules when the air is moving either faster (rapid breathing) or when the air is denser (deeper diving). Deeper diving and rapid breathing can compound this tendency.

In any case, with any reabreather, what seems also critical beyond just the style of scrubber is avoiding circumstances where you are likely to end up hyperventilating. the channeling caused by actually mixing of used and unused scrubber as exemplified in the video triggered a domino effect on the diver, triggering the Co2 spiral...which is why mixing/repacking scrubber is strongly advised against. Once co2 breaks through, it starts a downward spiral effect of hyperventilation, reduced dwell time, increased numbers of co2 molecules getting through, blood co2 rising, loop co2 rising, further degrees of hyperventilation until something is done to reverse the trend- and just as with N off gassing, once co2 builds up to dangerous levels in the blood it takes time to "off gass it", as illustrated by the way the diver in the video kept hyperventilating even after he bailed to OC.

CaptnJack wrote:After watching the CO2 hit video last week, I'd be disinclined to swap canisters. Just replace both after a few hours of diving and don't try to be cheap and stupid.

That would be my inclination as well.