Probably stupid question from a non-RB person

[DiveNav]

.....Theory and practice are not the same, eventhough in theory, they are.

Yes .... something related to muscle memory ....... but ... my math professor once told me: "chi sa, sempre sa fare, ma chi sa fare, non sempre sa" ..... that translated in English means" "whom who knows always knows how to do, but whom who does not always knows" .... for what is worth

Alberto (aka eDiver)

 

[TSandM]

Thanks so much, guys; this has been educational.

I had fun talking to Mel. I learned a bunch of things, and she had me shrug into her Revo so I could see how light it was. I'm not headed for the dark side any time soon, but it was very interesting.

 

[Cave Diver]

I'm not headed for the dark side any time soon, but it was very interesting.

Didn't you say the same thing about tech/cave diving?

 

[limeyx]

Some divers plumb their bailout valve to their offboard bailout gas supply, and make that their primary means of bailout. Others might choose to plumb their BOV to their onboard diluent tanks, and use the BOV for sanity breaths only. Onboard tanks are typically 20cf or less, and most likely will not have enough gas to sustain an OC ascent. Other divers might have gas shut-offs, manifolds, or gas switching blocks routed to their BOV. Many ccr divers, like myself, do not use a BOV. (gasp!)

If you have no plan with your ccr buddy, or you should happen to stumble across a ccr diver unconscious underwater, a dil flush is always the best idea. For recreational depths, a dil flush should always provide a breathable gas to the CCR diver, and will correct a hypoxic or hyperoxic loop. Dil flushes are the most basic skill taught to a CCR diver. I even saw one rebreather diver who placed a "press to rescue" label pointing towards his diluent addition button.

Don't worry about trying to figure out how to dump counterlungs. It's too much to ask from a task loaded diver trying to perform a rescue on an unconscious diver with unfamiliar equipment. Dumping the counterlungs incorrectly could result in flooding the loop, and a very negative unconscious diver. Most CCR's have an over-pressure relief valve to vent expanding gas from anyway.

Well, to me a "BOV" is just that --- what you bail out of the rebreather onto. It needs to be breathable at any depth (i suppose some exceptions for extremely hypoxic mixes at shallow depth) and enough gas to not immediately require some other gas source to be located. (i.e. enough gas to get me to the surface, a deco bottle, or stage/safety bottle)

I guess some define BOV differently (High PPo2 bailout, a small tank for "a few breaths" until another gas source is found).

That is another situation altogether and as you say in general there are many many ways people do do it.

 

[TSandM]

Didn't you say the same thing about tech/cave diving?

Did you notice the "any time soon"? I have learned never to say never with respect to this sport . . .

 

[rjack321]

I'm unfamiliar with that unit, but I don't like the idea of not being able to do a quick dil flush, or my OC buddy not knowing how to do one for me. That's part of our pre-dive planning. Since I'm too lazy to type it all out again, I'll repost my response from this thread: http://www.scubaboard.com/forums/advanced-scuba-discussions/308080-ccr-oc-buddies.html

This is essentially my approach. I am not going to go mucking about with someone's SCR, CCR manual or electronic, with or with ADVs, figuring out what I think your HUD is telling you, what I think you're ignoring, trying to make your loop life-sustaining etc. etc.

I have a long hose its basically always breathable. If you communicate or fail to communicate to me as expected during the dive you'll have that OC reg in front of you. If you are unconcious, I will put it in your mouth as expeditiously as possible.

I don't see the point of doing a dil flush for someone else. Yes it corrects a hypoxic loop but the loop is hypoxic for in all likeihood not having O2 (off or empty) so its at best very temporary, they might sorta wakeup but they'll need to be on bailout anyway. It could reduce ppO2 long enough to allow them to stop seizing but only if the original fault in the O2 add is somehow corrected (unlikely while they are unconcious) so again what is the dil flush doing for the injured diver & rescuer? It does keep the mouthpeice in, but its just delaying the inevitable OC (or BOV) reg needing to be in their mouth.

I have never understood having a BOV plumbed to a tiny onboard tank but that's a different issue.

 

[JKPAO]

Rjack some really good points!
See you topside! John

 

[muddiver]

I'm unfamiliar with that unit, but I don't like the idea of not being able to do a quick dil flush, or my OC buddy not knowing how to do one for me. That's part of our pre-dive planning. Since I'm too lazy to type it all out again, I'll repost my response from this thread: http://www.scubaboard.com/forums/advanced-scuba-discussions/308080-ccr-oc-buddies.html

You missed the statement earlier about how to flush a KISS. It is pretty simple and you can really change the gas fast.

I learned three ways: 1. Let gas from the loop escape past your lips and the mouth peice, then breathing in on deflated counter lungs will kick the ADV open. 2. Lean back until the ADV kicks in due to the change in pressure because it is now below your lungs, and let the gas escape as before. 3. open the BOV half way, when you breath in you get diluent (if it is attached to your diluent cylinder), when you breath out it exhausts through the open circuit BOV.

Also, down4fun, with the KISS I tend to notice the bressure in the loop building up if the O2 is out running my motabolism as well as the senor readouts going higher. Most RB divers probably never notice that.

 

[down4fun]

Also, down4fun, with the KISS I tend to notice the bressure in the loop building up if the O2 is out running my motabolism as well as the senor readouts going higher. Most RB divers probably never notice that.

You're right when the O2 was outrunning my metabolism the loop volume was increased, and thus the resistance when exhaling was increased. With the rEvo micro i find the loop volume to be pretty touchy.

 

[limeyx]

This is essentially my approach. I am not going to go mucking about with someone's SCR, CCR manual or electronic, with or with ADVs, figuring out what I think your HUD is telling you, what I think you're ignoring, trying to make your loop life-sustaining etc. etc.

I have a long hose its basically always breathable. If you communicate or fail to communicate to me as expected during the dive you'll have that OC reg in front of you. If you are unconcious, I will put it in your mouth as expeditiously as possible.

I don't see the point of doing a dil flush for someone else. Yes it corrects a hypoxic loop but the loop is hypoxic for in all likeihood not having O2 (off or empty) so its at best very temporary, they might sorta wakeup but they'll need to be on bailout anyway. It could reduce ppO2 long enough to allow them to stop seizing but only if the original fault in the O2 add is somehow corrected (unlikely while they are unconcious) so again what is the dil flush doing for the injured diver & rescuer? It does keep the mouthpeice in, but its just delaying the inevitable OC (or BOV) reg needing to be in their mouth.

I have never understood having a BOV plumbed to a tiny onboard tank but that's a different issue.

The one thing I would add here (at least if we ever go diving with me on the death-machine

is that you know how to close the loop as you give the long-hose (which in my case and maybe all ? also activates the BOV)

if not, water will continue to leak into the loop/lungs/canister and make for a very ugly day.

i do agree though, it's highly best not to do anything more than that.