Where should I start to approach the rebreather world

[happy-diver]

I would like to explore and learn about the rebreather world and then evaluate this leap.

Nico!

What I did was buy a Draeger Dolphin for a couple of hundred dollars and went diving

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What about an AP Inspiration

My money tree can cope with

 

[Wibble]

To be a little picky, there’s no issues diving a rebreather in a mixed ‘team’. You just give them your bailout, first the hose then the cylinder.

Then charge them the cost of the fill plus putting the cylinder back into test

 

[Tassi Devil Diver]

the Revo has higher annual maintenance costs to any other rebreather due to the quantity of cells that are in it. The Revo has 5,

Not true, the rEvo procedure is to replace a cell every 6 months, not to replace all cells annualy.

 

[broncobowsher]

Not true, the rEvo procedure is to replace a cell every 6 months, not to replace all cells annualy.

Don't know who taught you that. But 5 cells at 6-month rotation leaves the oldest cell at 2½ years old. That isn't good.

There is no denying that the rEvo has the most cells, and they do need to be changed. That is more money to have the cells fresh as compared to any other rebreather that has equally fresh cells. Really there is no physical reason you can't throw splitters on some cells and run just 3 cells like most other rebreathers. But the rEvo philosophy is run 5 cells, some even run 6. But depending on your profiles you can make that up is sorb savings, without pushing the sorb to the ragged edge of safety.

 

[Tassi Devil Diver]

Don't know who taught you that.

Was taught as a part of my rEvo Mod 1 as outlined in http://www.revo-rebreathers.com/wp-content/uploads/2016/02/Understanding_oxygen_sensors.pdf, and have followed this procedure since 2013, have only had three cells fail before being rotated out of my unit. Adding a splitter removes the advantage of two independent and redundant PO2 monitoring systems which I like.

 

[Heat Miser]

Don't know who taught you that. But 5 cells at 6-month rotation leaves the oldest cell at 2½ years old. That isn't good.

There is no denying that the rEvo has the most cells, and they do need to be changed. That is more money to have the cells fresh as compared to any other rebreather that has equally fresh cells. Really there is no physical reason you can't throw splitters on some cells and run just 3 cells like most other rebreathers. But the rEvo philosophy is run 5 cells, some even run 6. But depending on your profiles you can make that up is sorb savings, without pushing the sorb to the ragged edge of safety.

Its not quite strictly a new cell every 6 months,

The suggested policy is replace one cell no later than every six months, assuming that a sensor does not become current limited, otherwise its replace when becomes current limited which may be less than 6 months, and then start the clock on another 6 month period/current limit check from time of replacement.

Using the paper and rEvo's policy 3 they estimate/simulate its on average of a new cell every 100 days.

Although I do have cells that are a year and a half old and seems to be far better than any of my other newer cells in the unit and may get to 2 1/2 years old using policy 3.

I'm supposed to do MOD 2 with Rubens down in Tassie next month, are you guys going to let him in? @Tassi Devil Diver

 

[Teleopsis]

Given your circumstances I'd get a JJ. You can dive it in GUE config and then if you decide that a 55Kg super complicated monster on your back with a single failure point that will dump all your dil and all your bailout if it goes (the shonky flexible manifold) and a silly long hose stowed under the loop is not for you then you can dive it in standard config

 

[Nico-ITA]

Given your circumstances I'd get a JJ. You can dive it in GUE config and then if you decide that a 55Kg super complicated monster on your back with a single failure point that will dump all your dil and all your bailout if it goes (the shonky flexible manifold) and a silly long hose stowed under the loop is not for you then you can dive it in standard config

This is a very interesting consideration and for this reason I would like to start now to deepen the construction of the single machines, so as to make an objective reasoning on the reb, its functioning, its safety etc, together with the methodics, the standards and the customizations proposed by the agencies that provide the training.
By the way, 50kg or more seems to me a nightmare

Just for a quick comparison, what is the average weight of a rEvo mini or micro?

 

[Wibble]

... the Revo has higher annual maintenance costs to any other rebreather due to the quantity of cells that are in it. The Revo has 5,

A common myth and misinformation.

5 cells are less susceptible to a single or dual cell failure. Most importantly to have two fully independent computer systems that are not cross-connected, one with three cells and the wholly independent backup (nerd or Revo Dreams) with two cells.

I experienced a two cell failure on my MOD1 and it was exceedingly clear to see that two cells were slow to respond. A JJ doesn’t have this as the two monitors (Petrel controller + flashing HUD or Nerd) are interconnected to the same three cells so will both show the same wrong information in case of a double cell failure. There are cell failure modes that could render you 'blind' as the monitors are connected together at the cells; the Revo has two completely independent monitoring systems.

As all three-cell rebreathers are more susceptible to single cell failures, you end up replacing perfectly good cells as a risk-mitigation strategy. Revos allow the perfectly good cells to continue, as per the papers linked here and here.


Whilst we’re on the topic of costs, let’s talk about your single scrubber. How do you know when it’s expired? Aside from runtime, you’ve no way to determine this so you have to be far more conservative unless you "push the scrubber" and get a potential breakthough.

A Revo on the other hand has two scrubbers and a very effective "RMS" (Revo Monitoring System) temperature-sensing monitoring system that determines where the reaction front is and can be used to diagnose scrubber problems (only the AP Inspiration "Temp Stick" is similar, but that is a single scrubber). The RMS determines the amount of scrubber time left, but most importantly, tells you when the second scrubber's being used, such as from channeling.

Most rebreathers use a single large >3kg+ / >5pound scrubber and have to throw the lot away when you refill it. The Revo uses two 1.3kg/2.8pound scrubbers in series and you normally only ever re-fill a single scrubber, switching the second lower scrubber to the top (first position) and re-fill only the expired scrubber.

Therefore a Revo saves you a fortune in scrubber lime compared with all other rebreathers.

A Revo is also far more resilient to scrubber breakthrough, channeling, as there's two independent scrubbers in series. The exhaust gas going through one scrubber, then is mixed before going through the second scrubber. The RMS will warn you when the reaction front reaches the second scrubber -- as that's independent of the first, the system is exceedingly accurate.


Very happy to continue to refute the Revo bashing. Seems common to attack something that's different.

 

[Wibble]

Just for a quick comparison, what is the average weight of a rEvo mini or micro?

A fully configured Revo Mini titanium with 3 litre oxygen and diluent cylinders, a steel 2 litre suit inflate cylinder, a stainless stand, umbilical torch, two full scrubbers, it weighs 44kg. You can reduce this, but need additional weight with a drysuit.

Add the bailouts (single ali7 <35m, two ali7's to 50m, two ali80s to 70m).