Important features when choosing a rebreather

[tbone1004]

Is a sealed Tupperware box OK? Once the CO2's been scrubbed from the surrounding space in the tub, that's it?

I would imagine so, though you don't want the scrubber rolling around

 

[broncobowsher]

I store my lightly used scrubber in a tupperware container. Don't see that as much different that the jug I pour it out of. That was never vacuum sealed.

 

[macado]

Is a sealed Tupperware box OK? Once the CO2's been scrubbed from the surrounding space in the tub, that's it?

I keep my partially used scrubbers in either a waterproof dry bag or in the case of the rEvo, inside tupperware containers.

This is an interesting study that compares sealed scrubber with one left open.
Storage of partly used closed-circuit rebreather carbon dioxide absorbent canisters

Results
We completed five trials in each of the 28-day-sealed and overnight-open conditions, and four experiments in the 28-day-open condition. Unfortunately, we exhausted our same-batch supply of Sofnolime 797 with one trial in the 28-day-open condition remaining to be done. We attempted to run the trial with Sofnolime from another batch and obtained an aberrant result. Given the confluence of the results obtained in the trials performed using Sofnolime from the common batch (see below) we considered it reasonable to stop the study one trial short in the 28-day-open condition, rather than repeat the entire study with a new batch of Sofnolime.

The elapsed times to reach the failure end-point in each scrubber trial arranged by storage condition, and the mean times to failure for each condition are shown in Table 1. The breakthrough curves for each scrubber trial are shown in (Figure 2). There was a substantial (> 50 min) difference in mean duration to failure between scrubbers stored for 28 days in the sealed condition (longer) compared to the open condition (shorter; P = 0.003). Scrubbers stored 'open' for the much shorter overnight period showed no difference in mean duration to failure when compared to the canisters sealed for 28 days.

TL;DR In short for overnight storage you could simply leave it out on the bench and it doesn't make a huge difference. Longer duration it should be stored sealed otherwise it loses scrubber capacity.

 

[GF99/99]

I am new to rebreathers and I am trying to figure out which features to have so that I can shortlist models that would be suited for me. From my research, I landed on 3 features that not all units have that would make diving easier and safer

• ADV – Auto Diluent Valve (with or without a Flowstop isolator) — to automatically inflate counterlung when going deeper
• Scrubber Life Monitor — the scrubber is the bottleneck for dive duration and hence great to monitor it
• CO2 Sensor — Important for safety

Anybody would agree with these 3 being important features? Which models would fit the bill?

Right now your looking at what kind of rims you should get for your car when you should first be trying to figure out if you want a truck, SUV, minivan or sports car.

Firstly what type of diving are you looking to use this for??
Overhead/cave
Deep trimix exploration dives
Recreationally
Do you want electronic or manual
Something travel friendly
What is your location and availability of support and instructors

I think these are the factors you should first be looking at because there are so many different units on the market now and many are configured for specific types of diving. For example look at the vast differences between a Sidewinder, Meg, and that thing Mares has come out with.

Honestly an ADV flow stop, scrubber life monitor, and Co2 sensor IMO would not really be things I would be particularly interested in when picking out a rebreather. ADV flow stop can be added for $50, scrubber life monitor and Co2 sensor these just are not practical at this point in time.

 

[Jack Hammer]

What helped me decide on a unit was talking to people in person and asking them a lot of questions and listening to their answers. I didnt do this online because I wanted honest opinions not justifications for their choice. Typical questions were:

How long have you been diving your unit?
Is it your first rebreather or did you have others?
How do you like your unit overall?
What do you really like about it?
What do you dislike?
What would you change?
Would you buy it again?
If money were no object what unit would you buy?
Why that one?

I was quite surprised how many people would go with something else if money wasn't a factor in choosing. These conversations really helped me to understand different rebreathers more, get a general consensus, and narrow my list. So far I'm happy with my decision overall.

I've learned no rebreather is perfect, not even mine. There will always be some things you dont like or wish you could change. It is about finding the best compromise for your needs.

 

[tbone1004]

@Jack Hammer money no object I would ditch my Meg and my kisskat and get a Liberty. I may well do all of that with the sidemount Meg later this year since it gets rid of most of my issues with my sidemount unit, but it wasn't available at the time and I built the sidemount unit for under $5k with sphere and computer and didn't have another $5k to drop on a unit since I had just built the booster case

 

[LFMarm]

Thanks all for chipping in. Your feedback tells me I need to do much more research. To get started, here is the answer to some of the questions you suggested to start from:

• Intended use: rec, tek (trimix to moderate depth), not aggressive wreck, no cave
• Electronics: hybrid (I love the suggestion from tbone1004 that every electronic unit can be converted to hCCR)
• Setup: sidemount
• Other pros for me: travel friendly (it will be only used when travelling), easy to maintain and assemble/disassemble
• Location: US

Additional context: This would be my first rebreather. I am a sidemount OC diver, with about 300 dives, I recently used an AP for a couple of dives and loved the feeling of a rebreather, doing a trimix class in December

Firstly what type of diving are you looking to use this for??
Overhead/cave
Deep trimix exploration dives
Recreationally
Do you want electronic or manual
Something travel friendly
What is your location and availability of support and instructors

How long have you been diving your unit?
Is it your first rebreather or did you have others?
How do you like your unit overall?
What do you really like about it?
What do you dislike?
What would you change?
Would you buy it again?
If money were no object what unit would you buy?
Why that one?

 

[rjack321]

I would absolutely not get a sidemount CCR - they are a specialized tool with a whole bunch of compromises. A backmounted JJ, Meg, fathom, revo, or defender would be a better choiceBut if you insist on a sidemount unit, there are no stock hCCR sidemount units. Only a couple eCCR SM units which you would have to modify it in the future after training to be hCCR.

The SF2 and the liberty. Both are at least available in the USA, but neither have scrubber duration or CO2 sensors. There are probably ways to add an orifice but I've never heard of anyone who has. For every hCCR aficionado on the internet, there are at least as many divers who consider them to have all the flaws of both approaches and none of the value of either.

 

[tbone1004]

I would absolutely not get a sidemount CCR - they are a specialized tool with a whole bunch of compromises. A backmounted JJ, Meg, fathom, revo, or defender would be a better choiceBut if you insist on a sidemount unit, there are no stock hCCR sidemount units. Only a couple eCCR SM units which you would have to modify it in the future after training to be hCCR.

The SF2 and the liberty. Both are at least available in the USA, but neither have scrubber duration or CO2 sensors. There are probably ways to add an orifice but I've never heard of anyone who has. For every hCCR aficionado on the internet, there are at least as many divers who consider them to have all the flaws of both approaches and none of the value of either.

I would absolutely not get a sidemount CCR - they are a specialized tool with a whole bunch of compromises. A backmounted JJ, Meg, fathom, revo, or defender would be a better choiceBut if you insist on a sidemount unit, there are no stock hCCR sidemount units. Only a couple eCCR SM units which you would have to modify it in the future after training to be hCCR.

The SF2 and the liberty. Both are at least available in the USA, but neither have scrubber duration or CO2 sensors. There are probably ways to add an orifice but I've never heard of anyone who has. For every hCCR aficionado on the internet, there are at least as many divers who consider them to have all the flaws of both approaches and none of the value of either.

seconded and I'm not sure I would modify mine to be an hCCR. With the needle valves it is less annoying since they don't have to be plugged but I abhor CMF with fixed first stages from the PITA factor of the first stage itself.

 

[LFMarm]

What are the compromises in sidemount rebreathers?

I would absolutely not get a sidemount CCR - they are a specialized tool with a whole bunch of compromises.