Revo BOV questions

[Wibble]

No mention of the RMS -- Revo Monitoring System -- which gives a very good estimate of remaining scrubber usage based on the reaction front's temperature.

Better still, should a used scrubber be accidentally refitted (I swear I changed the 'sorb) then the RMS will indicate this, especially in the pre-jump pre-breathe where you wait for at least 45mins to show on the RMS.

Would be fascinating to do a dive with only ONE scrubber filled. How would the RMS display this?

 

[ahereng]

barrel roll. Was taught to my on the Meg in my initial Mod1 course.

What I was taught during my Meg course was to compress the exhale-hose between dsv/bov and t-piece and blow. The goo is then very effective blown into the exhale-lung.

 

[ahereng]

I didn't see Flymolo's answer before I posted mine.. Same thing.

 

[Wibble]

Revo’s don’t have a T-piece, the hoses go straight into the unit over your shoulders.

 

[Wibble]

What is the consensus regarding the Revo BOV? Is it good? Better than X or Y? Anyone used one deep? Good flow in heavy breathing? Light or heavy in use? Easy & convenient?

 

[cathal]

What is the consensus regarding the Revo BOV? Is it good? Better than X or Y? Anyone used one deep? Good flow in heavy breathing? Light or heavy in use? Easy & convenient?

I am told they are built to EN250 standard. That’s a scuba Reg build standard. WOB will always be a function of the amount of helium in your BO mix. I would advise you look up Mitchel et al on the correlation between WOB and incidents. Mitchel concluded that once you go past( l think from memory it was 6.2 Joules per litre) the number of incidents increased enormously. He had a recommendation in Joules per litre that he advocated for a safe WOB. I applied this level ( think it was something like 6.2 - 5.2 J/L) and it meant a big increase in % of He and usually it would end up with you having an END on your bottom mix or BO mix of 20M approximately. It was covered it in the proceedings from RB Forum 3.0 I think.

 

[Wibble]

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.

Barrel rolls must NOT be performed on a Revo to clear liquid from the loop

A Revo has its two scrubbers above the diver when flat and are effectively one side of the lungs. A "barrel roll", rotating 360 longitudinally, will tip any liquid in the lungs straight into the scrubbers soaking them and ultimately destroying their scrubbing abilities. Liquid from the top scrubber will pass through to the lower scrubber and into the inhale lung.

The end result will be impaired scrubber effectiveness or in the worse case a caustic cocktail requiring a full bailout and possibly wrecking the oxygen sensors.

A barrel roll on a Revo is the equivalent of going head down if you suspect water in the scrubber canister in tubular scrubbers.

 

[Dsix36]

While both tbone and Wibble have valid points I believe there needs to be some clarification. In my original rEvo training, back in the days of dinosaurs, we were taught to merely roll onto our side while shaking the loop hose. This will move the water into the exhale counterlung. and as we would roll back we would go a tad bit head up to keep it from running back down the loop hose, and subsiquently be absorbed by the sham-wow in the bottom of the counterlung rather than getting into the scrubber. This works well for normal condensation or minor little screw ups with loose lips but for a serious flood it will soak the scrubbers. You can dewater a rEvo BUT you had better of practiced it a lot before you try it in real life. It is NOT easy.

 

[Wibble]

While both tbone and Wibble have valid points I believe there needs to be some clarification. In my original rEvo training, back in the days of dinosaurs, we were taught to merely roll onto our side while shaking the loop hose. This will move the water into the exhale counterlung. and as we would roll back we would go a tad bit head up to keep it from running back down the loop hose,

This is current training — as of my MOD1 a couple of years ago.

and subsiquently be absorbed by the sham-wow in the bottom of the counterlung rather than getting into the scrubber.

In normal circumstances there is no water route from the exhale (top) counterlung to the inhale (bottom) counterlung where the absorbent cloth is located. There is a gas route via the scrubber canisters, but that is vertically upwards, so water stays in the exhale lung where there is no absorbent cloth.

This works well for normal condensation or minor little screw ups with loose lips but for a serious flood it will soak the scrubbers.

If you dive completely flat or go head down due to the topography it is possible for any free moving liquid in the exhale lung to tip into the exhale loop. This will gurgle at the exhale flapper valve and can enter the DSV mouthpiece and cause a wet breathe. This is irritating and annoying.

Revo do not recommend placing a cloth in the exhale lung as it could interfere with the ADV lever should the cloth move.

I have found that an absorbent cloth cut in half and loosely rolled will fit nicely vertically behind the cables on the left-hand side of the exhale lung below the exhale loop entry (as viewed when open). This cloth nicely absorbs a couple or few teaspoons of "loose lips" water, even when head down — a dry breathe, no annoying gurgling.

This will not work if you have a leak with cupfuls of water.

As every Revo diver knows, or is yet to learn, the DSV (Dive Surface Valve) must be fully open or closed to fully seal.

If you dive with the DSV partially open — for example if it is knocked when you fell flat on your face when exiting the boat when your clown shoes caught on the dive lift (moi?) — the DSV will continue to leak water in the loop until fully closed. You may think it is a teaspoonful when it actually is cupfuls of water.

One barrel roll later, or even going past 90 degrees on your side, will tip that water through the exhale scrubber, possibly ending up in the inhale scrubber and counterlung. The worst case being a caustic cocktail, a flooded (= destroyed) pair of scrubbers (indicated by a high work of breathing) and — for the full house — a CO2 hit. Only a full bailout will save you.

(Wonder how I know this…)

You can dewater a rEvo BUT you had better of practiced it a lot before you try it in real life. It is NOT easy.

I really would like to know how to do that.

With the absence of a dump in the bottom of the exhale lung or a "pump dump in a sump" after the exhale mushroom valve, I can’t see an official technique. (V. happy for a PM if not a public discussion)

 

[JonG1]

This is current training — as of my MOD1 a couple of years ago.


In normal circumstances there is no water route from the exhale (top) counterlung to the inhale (bottom) counterlung where the absorbent cloth is located. There is a gas route via the scrubber canisters, but that is vertically upwards, so water stays in the exhale lung where there is no absorbent cloth.


If you dive completely flat or go head down due to the topography it is possible for any free moving liquid in the exhale lung to tip into the exhale loop. This will gurgle at the exhale flapper valve and can enter the DSV mouthpiece and cause a wet breathe. This is irritating and annoying.

Revo do not recommend placing a cloth in the exhale lung as it could interfere with the ADV lever should the cloth move.

I have found that an absorbent cloth cut in half and loosely rolled will fit nicely vertically behind the cables on the left-hand side of the exhale lung below the exhale loop entry (as viewed when open). This cloth nicely absorbs a couple or few teaspoons of "loose lips" water, even when head down — a dry breathe, no annoying gurgling.

This will not work if you have a leak with cupfuls of water.

As every Revo diver knows, or is yet to learn, the DSV (Dive Surface Valve) must be fully open or closed to fully seal.

If you dive with the DSV partially open — for example if it is knocked when you fell flat on your face when exiting the boat when your clown shoes caught on the dive lift (moi?) — the DSV will continue to leak water in the loop until fully closed. You may think it is a teaspoonful when it actually is cupfuls of water.

One barrel roll later, or even going past 90 degrees on your side, will tip that water through the exhale scrubber, possibly ending up in the inhale scrubber and counterlung. The worst case being a caustic cocktail, a flooded (= destroyed) pair of scrubbers (indicated by a high work of breathing) and — for the full house — a CO2 hit. Only a full bailout will save you.

(Wonder how I know this…)



I really would like to know how to do that.

With the absence of a dump in the bottom of the exhale lung or a "pump dump in a sump" after the exhale mushroom valve, I can’t see an official technique. (V. happy for a PM if not a public discussion)

Sounds like a bit of a do Wibs, do u reckon u were on the verge of hypercapnia?

How deep when you bailed?

Shot or SMB.

PS Glad u survived etc.