Revo BOV questions

[Wibble]

Some usage questions regarding the Revo bailout valve mouthpiece...

Is it possible to "dump" a slight flood out of the BOV? Meaning if there's some liquid in the exhale side that's bubbling against the mushroom, is there a way of blowing that out? It's annoying how a couple of teaspoons of liquid are such a damn nuisance.

How well does the Revo BOV work in comparison with other brands? Have heard good things but have never used a BOV on a box before.

For Revo divers: the main purpose of a BOV is for a CO2 hit: everything else is pretty straightforward to deal with. What is the likelihood of some form of CO2 hit on a Revo -- AFAIAA it's pretty negligible with the Revo.


I'm most concerned with the additional hassle a BOV brings compared with the simplicity of a simple bailout. Or am I overthinking things? The $1k for the BOV and quick connects doesn't help!


Are there any other benefits of the Revo BOV?

 

[tbone1004]

You can only dump liquid out of the exhale side by getting it out of the loop and somewhere else, check valve will stop it from going back into the mouthpiece. Barrel rolls work well for this.

Revo is no more or less susceptible to CO2 than any other unit, contrary to what everyone says. Why do you think it is negligible with the Revo but not on other units?

BOV is convenient if you do a lot of scootering as bailing out can be somewhat uncomfortable if you have to tuck the loop under your chin.

 

[cathal]

Revo is no more or less susceptible to CO2 than any other unit, contrary to what everyone says. Why do you think it is negligible with the Revo but not on other units?

He might be referring to the twin scrubber arrangement whereby if there is a bypass or channeling in the top scrubber the bottom scrubber would then catch the CO2 that bypassed the firt scrubber and vice versa.

 

[cathal]

Some usage questions regarding the Revo bailout valve mouthpiece...

How well does the Revo BOV work in comparison with other brands? Have heard good things but have never used a BOV on a box before.

For Revo divers: the main purpose of a BOV is for a CO2 hit: everything else is pretty straightforward to deal with. What is the likelihood of some form of CO2 hit on a Revo -- AFAIAA it's pretty negligible with the Revo.


I'm most concerned with the additional hassle a BOV brings compared with the simplicity of a simple bailout. Or am I overthinking things? The $1k for the BOV and quick connects doesn't help!


Are there any other benefits of the Revo BOV?

There are literally hundreds of pages of threads written on the effectiveness of a BOV on a CCR both on this forum and elsewhere. I would suggest if you want to learn about this piece of equipment just simply type in BOV into the search field at the top and start reading.

We all have our own views on them, and I use one on a rEvo. Re the rEvo BOV I understand it performs as per the EN 250. standard which I think bottoms out at 50M depth. But then is this depth even relevant or is the actual breathing gas density at depth more relevant??

 

[tbone1004]

He might be referring to the twin scrubber arrangement whereby if there is a bypass or channeling in the top scrubber the bottom scrubber would then catch the CO2 that bypassed the firt scrubber and vice versa.

The scrubbers are not redundant, so dual scrubbers doubles the risk of a bad pack and increases the sealing o-rings to prevent bypass. From an engineering standpoint I would argue it actually increases the risk of a CO2 hit. Now it is certainly incredibly convenient to have the lower profile and really nifty to be able to remove the first scrubber and swap the second in and repack which makes it more efficient use of sorb, but any arguments about mitigating risk of CO2 are not founded in reality.

 

[cathal]

The scrubbers are not redundant, so dual scrubbers doubles the risk of a bad pack and increases the sealing o-rings to prevent bypass.

Can you explain this to me again as I am findining it difficult to grasp your concept. My understanding is that each scrubber canister in the rEvo is completely physically separated from the other. They are in their own individual housings and there is a gas channel in the lid that funnels the gas flow in between each scrubber.
They are both packed independently from the other ergo if one is packed badly then you have the second scrubber to catch any bypassed CO2 with the second independent scrubber.
Or do I have this wrong??

 

[sprockjohnson]

I would argue that there is some redundancy, however not in an independent fashion. Each scrubber could be a redundant backup to the other for CO2 scrubbing but as tbone004 stated the extra o-rings add failure points and you run the risk of flooding both "redundant" scrubbers if there was to be a leak without any effective way of clearing the moisture/ water/ flood- which brings us back to the original question regarding clearing of water from the exhale loop through the mushroom valve.

I don't have a BOV on my rEvo and so therefore have no first hand experience with this situation but I would have to agree with tbone004 that it would not help because the water would still be trapped in the loop by the one-way mushroom valve.

 

[tbone1004]

Can you explain this to me again as I am findining it difficult to grasp your concept. My understanding is that each scrubber canister in the rEvo is completely physically separated from the other. They are in their own individual housings and there is a gas channel in the lid that funnels the gas flow in between each scrubber.
They are both packed independently from the other ergo if one is packed badly then you have the second scrubber to catch any bypassed CO2 with the second independent scrubber.
Or do I have this wrong??

They are inline scrubbers, gas flows from the first one into the second one. If you have a bad pack in the first then the second will catch it but the first scrubber is not being used completely so your risk of breakthrough actually increases if you are running long profiles. If you have a bad pack in the second then as soon as the reaction front gets into the second you have breakthrough. Below is copied from the manual that shows the gas path. The benefit of the dual scrubbers is reduced CO2 usage since you can move the exhale side into the inhale side and repack, there is no safety improvements with regards to CO2 in this design. Sidewinder divers/instructors make the same incorrect claims about the sidewinder.

 

[tbone1004]

I would argue that there is some redundancy, however not in an independent fashion. Each scrubber could be a redundant backup to the other for CO2 scrubbing but as tbone004 stated the extra o-rings add failure points and you run the risk of flooding both "redundant" scrubbers if there was to be a leak without any effective way of clearing the moisture/ water/ flood- which brings us back to the original question regarding clearing of water from the exhale loop through the mushroom valve.

I don't have a BOV on my rEvo and so therefore have no first hand experience with this situation but I would have to agree with tbone004 that it would not help because the water would still be trapped in the loop by the one-way mushroom valve.

The scrubbers might be able to be considered redundant if and only if you only ever intend to use the duration of a single scrubber AND repack both scrubbers every single time. If you use the unit the way Revo recommends and move the second scrubber to the first slot and repack then you remove ALL arguments for redundancy, and if you ever plan a dive for more than half of the rated runtime you remove ALL arguments for redundancy on this unit.
I would strongly recommend you remove any thoughts about that scrubber system being redundant from your thinking as I can all but guarantee there is not a single Revo diver that dives that way.

 

[cathal]

They are inline scrubbers, gas flows from the first one into the second one. If you have a bad pack in the first then the second will catch it but the first scrubber is not being used completely so your risk of breakthrough actually increases if you are running long profiles. If you have a bad pack in the second then as soon as the reaction front gets into the second you have breakthrough. Below is copied from the manual that shows the gas path. The benefit of the dual scrubbers is reduced CO2 usage since you can move the exhale side into the inhale side and repack, there is no safety improvements with regards to CO2 in this design. Sidewinder divers/instructors make the same incorrect claims about the sidewinder.

View attachment 719448

Thanks for your response. To quote from your response

"f you have a bad pack in the first then the second will catch it but the first scrubber is not being used completely so your risk of breakthrough actually increases if you are running long profiles"​

Can I ask why do you think this is the case? Bearing in mind that the whole dea of diving the rEvo is based on the top scrubber scrubbing all of the CO2 and the bottom one acting as a secondary scrubber to catch any residual CO2?

Cheers