VR3 Bailout question

Drmike · 10th May 2006, 15:25

Quote: (Originally Posted by PCDiver)

It also depends on the bailout gas you are breathing.

obviously

Quote:

And the total loop volume. And the loop volume between the injection point and the cells. And ....
.

if you say so....

Personally my experience is it doesnt matter what unit Im using I apear to get the same eqv. drop in FO2 for the same frequency of venting/injecting.

divetheworld · 10th May 2006, 15:36

Quote: (Originally Posted by Drmike)

Personally my experience is it doesnt matter what unit Im using I apear to get the same eqv. drop in FO2 for the same frequency of venting/injecting.

Speaking of experience Mike, it looks like you have given SCR some thought as part of a dive plan or not?
I dont see it as a viable bail plan, just a means of keeping the noggin ticking until you sort it out. Thoughts?

Just curious what your point of view is.

Brent.

Drmike · 11th May 2006, 05:11

Quote: (Originally Posted by divetheworld)

Speaking of experience Mike, it looks like you have given SCR some thought as part of a dive plan or not?
I dont see it as a viable bail plan, just a means of keeping the noggin ticking until you sort it out. Thoughts?

Just curious what your point of view is.

Brent.

SCR is first choice over OC everytime if the loop is good.

Whenever its not possible to have lots of extra OC bail gas SCR is the way to go. Even if you vent every 2nd breath you are getting x2 gas extension!

You DO know your FO2 (you can assume a conservative drop in fraction) so long as you use the same (or less) freq of venting you are extending the safety margin the OC bail gas lasts with just a few% drop in FO2. Its not at all possible to go hypoxic unless your freq of venting is insane.

Just switch vr3 to OC gas reduce the FO2 a bit and follow

divetheworld · 11th May 2006, 06:30

Quote: (Originally Posted by Drmike)

SCR is first choice over OC everytime if the loop is good.

Whenever its not possible to have lots of extra OC bail gas SCR is the way to go. Even if you vent every 2nd breath you are getting x2 gas extension!

You DO know your FO2 (you can assume a conservative drop in fraction) so long as you use the same (or less) freq of venting you are extending the safety margin the OC bail gas lasts with just a few% drop in FO2. Its not at all possible to go hypoxic unless your freq of venting is insane.

Just switch vr3 to OC gas reduce the FO2 a bit and follow

I have never liked the 'not knowing the po2' of the inspired gas on ascent. Using whatever Dil in SCR is a lower fo2 than the cyl gas, combined with the reduction in fo2 due to the ascent makes my arse twitch. So my opinion was pure conjecture.
I suspected you had a differing opinion and thats why I thought to ask you. I've never bothered to work out a bail plan with the upward journey using SCR.

Brent.

GuyW · 11th May 2006, 10:05

Remember the drop in ppO2 is less (probably negligible) at depth than on your shallow deco stops. So I suggest you initially go to SCR with the VR3 just programmed to OC with that gas. Once you get your act together and get to your shallow stops, and you know your gas needs, then just go to OC.

Guy

Drmike · 11th May 2006, 10:45

Quote: (Originally Posted by divetheworld)

I have never liked the 'not knowing the po2' of the inspired gas on ascent. Using whatever Dil in SCR is a lower fo2 than the cyl gas, combined with the reduction in fo2 due to the ascent makes my arse twitch. So my opinion was pure conjecture.
I suspected you had a differing opinion and thats why I thought to ask you. I've never bothered to work out a bail plan with the upward journey using SCR.

Brent.

Hi Brent,

The way I figure it in a cave or deep OW dive with staged bailout tanks I would go SCR for the deepest section/ initial ascent where the small drop in FO2 has much less or no impact to the deco and where if I did just Bail to OC the gas consumption would have been the highest = more risk of running out before reaching next staged bail tank.

Having less than optimal FO2 means you may have a little more deco - but that wont necessarily get you killed - running out of OC bail gas in a cave certainly will get you killed!!

.

Of course one should try to carry enough bail gas to do full OC bail - but things can happen to increase RMV or other problems such as getting lost taking longer than expected or a sudden freeflow that eats into that finite reserve of life supporting gas.

Cheers
Mike

divetheworld · 11th May 2006, 12:02

Quote: (Originally Posted by Drmike)

Hi Brent,

The way I figure it in a cave or deep OW dive with staged bailout tanks I would go SCR for the deepest section/ initial ascent where the small drop in FO2 has much less or no impact to the deco and where if I did just Bail to OC the gas consumption would have been the highest = more risk of running out before reaching next staged bail tank.

Having less than optimal FO2 means you may have a little more deco - but that wont necessarily get you killed - running out of OC bail gas in a cave certainly will get you killed!!

.

Of course one should try to carry enough bail gas to do full OC bail - but things can happen to increase RMV or other problems such as getting lost taking longer than expected or a sudden freeflow that eats into that finite reserve of life supporting gas.

Cheers
Mike

Thats really good advise. I'm re-thinking now and will aim that way.

Ta.

Brent.

Padowan · 11th May 2006, 12:27

I guess one other thing to bear in mind if bailing to SCR is that if you're flapping about in a panic, will you be able to effectively execute SCR operation and keep the breathing ratio correct and consistent?

I still reckon that you want OC for a few sanity breaths to get your sh*t together...

Mdemon · 11th May 2006, 15:51

I wonder how confused a 4th cell VR£, plugged in and on CCR deco, would become if you went SCR?

Padowan · 12th May 2006, 07:38

Quote: (Originally Posted by Mdemon)

I wonder how confused a 4th cell VR£, plugged in and on CCR deco, would become if you went SCR?

It wouldn't get confused. It would track the PPO2 of the loop and base it's deco on that fluctuating PPO2. The predicted TTS would be all over the shop, and would increase and decrease as the PPO2 fluctuated, but the rate that the stops that were proposed counted down would be a direct function of the changing PPO2.

10th May 2006, 15:25	#11 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,325	Re: VR3 Bailout question Quote: (Originally Posted by PCDiver) It also depends on the bailout gas you are breathing. obviously Quote: And the total loop volume. And the loop volume between the injection point and the cells. And .... . if you say so.... Personally my experience is it doesnt matter what unit Im using I apear to get the same eqv. drop in FO2 for the same frequency of venting/injecting. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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10th May 2006, 15:36	#12 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,586	Re: VR3 Bailout question Quote: (Originally Posted by Drmike) Personally my experience is it doesnt matter what unit Im using I apear to get the same eqv. drop in FO2 for the same frequency of venting/injecting. Speaking of experience Mike, it looks like you have given SCR some thought as part of a dive plan or not? I dont see it as a viable bail plan, just a means of keeping the noggin ticking until you sort it out. Thoughts? Just curious what your point of view is. Brent. __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe Last edited by divetheworld : 10th May 2006 at 19:00.
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11th May 2006, 05:11	#13 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,325	Re: VR3 Bailout question Quote: (Originally Posted by divetheworld) Speaking of experience Mike, it looks like you have given SCR some thought as part of a dive plan or not? I dont see it as a viable bail plan, just a means of keeping the noggin ticking until you sort it out. Thoughts? Just curious what your point of view is. Brent. SCR is first choice over OC everytime if the loop is good. Whenever its not possible to have lots of extra OC bail gas SCR is the way to go. Even if you vent every 2nd breath you are getting x2 gas extension! You DO know your FO2 (you can assume a conservative drop in fraction) so long as you use the same (or less) freq of venting you are extending the safety margin the OC bail gas lasts with just a few% drop in FO2. Its not at all possible to go hypoxic unless your freq of venting is insane. Just switch vr3 to OC gas reduce the FO2 a bit and follow __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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11th May 2006, 06:30	#14 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,586	Re: VR3 Bailout question Quote: (Originally Posted by Drmike) SCR is first choice over OC everytime if the loop is good. Whenever its not possible to have lots of extra OC bail gas SCR is the way to go. Even if you vent every 2nd breath you are getting x2 gas extension! You DO know your FO2 (you can assume a conservative drop in fraction) so long as you use the same (or less) freq of venting you are extending the safety margin the OC bail gas lasts with just a few% drop in FO2. Its not at all possible to go hypoxic unless your freq of venting is insane. Just switch vr3 to OC gas reduce the FO2 a bit and follow I have never liked the 'not knowing the po2' of the inspired gas on ascent. Using whatever Dil in SCR is a lower fo2 than the cyl gas, combined with the reduction in fo2 due to the ascent makes my arse twitch. So my opinion was pure conjecture. I suspected you had a differing opinion and thats why I thought to ask you. I've never bothered to work out a bail plan with the upward journey using SCR. Brent. __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe
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11th May 2006, 10:05	#15 (permalink)
GuyW Old Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Apr 2006 Location: Sydney, Australia Posts: 61	Re: VR3 Bailout question Remember the drop in ppO2 is less (probably negligible) at depth than on your shallow deco stops. So I suggest you initially go to SCR with the VR3 just programmed to OC with that gas. Once you get your act together and get to your shallow stops, and you know your gas needs, then just go to OC. Guy
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11th May 2006, 10:45	#16 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,325	Re: VR3 Bailout question Quote: (Originally Posted by divetheworld) I have never liked the 'not knowing the po2' of the inspired gas on ascent. Using whatever Dil in SCR is a lower fo2 than the cyl gas, combined with the reduction in fo2 due to the ascent makes my arse twitch. So my opinion was pure conjecture. I suspected you had a differing opinion and thats why I thought to ask you. I've never bothered to work out a bail plan with the upward journey using SCR. Brent. Hi Brent, The way I figure it in a cave or deep OW dive with staged bailout tanks I would go SCR for the deepest section/ initial ascent where the small drop in FO2 has much less or no impact to the deco and where if I did just Bail to OC the gas consumption would have been the highest = more risk of running out before reaching next staged bail tank. Having less than optimal FO2 means you may have a little more deco - but that wont necessarily get you killed - running out of OC bail gas in a cave certainly will get you killed!! . Of course one should try to carry enough bail gas to do full OC bail - but things can happen to increase RMV or other problems such as getting lost taking longer than expected or a sudden freeflow that eats into that finite reserve of life supporting gas. Cheers Mike __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment Last edited by Drmike : 11th May 2006 at 10:49.
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11th May 2006, 12:02	#17 (permalink)
divetheworld Dive porn pimp Current Rebreather/s: Inspiration Classic Other CCR Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Classic Kiss Other CCR Join Date: Mar 2005 Location: Leeds, England Posts: 1,586	Re: VR3 Bailout question Quote: (Originally Posted by Drmike) Hi Brent, The way I figure it in a cave or deep OW dive with staged bailout tanks I would go SCR for the deepest section/ initial ascent where the small drop in FO2 has much less or no impact to the deco and where if I did just Bail to OC the gas consumption would have been the highest = more risk of running out before reaching next staged bail tank. Having less than optimal FO2 means you may have a little more deco - but that wont necessarily get you killed - running out of OC bail gas in a cave certainly will get you killed!! . Of course one should try to carry enough bail gas to do full OC bail - but things can happen to increase RMV or other problems such as getting lost taking longer than expected or a sudden freeflow that eats into that finite reserve of life supporting gas. Cheers Mike Thats really good advise. I'm re-thinking now and will aim that way. Ta. Brent. __________________ Attitude and self praise is no reccomendation. Dont try to be a great man, just be a man and let history be the judge of you. CHECK OUT OUR INTERWEBS FOR CUSTOM REBREATHER UPGRADES *WWW.NARKEDAT90.CO.UK* *http://www.grpservices.com/pursuit/* Supporting Shearwater Research Products in Europe
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11th May 2006, 12:27	#18 (permalink)
Padowan Proper Boffin Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Kent, UK. Posts: 518	Re: VR3 Bailout question I guess one other thing to bear in mind if bailing to SCR is that if you're flapping about in a panic, will you be able to effectively execute SCR operation and keep the breathing ratio correct and consistent? I still reckon that you want OC for a few sanity breaths to get your sht together... __________________ Padowan* The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
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11th May 2006, 15:51	#19 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,927	Re: VR3 Bailout question I wonder how confused a 4th cell VR£, plugged in and on CCR deco, would become if you went SCR? __________________ www.southwestmafia.com "small minds talk about people, Average Minds Talk About Events, GREAT MINDS TALK ABOUT IDEAS!" The WRONG Attitude will get you killed. "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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12th May 2006, 07:38	#20 (permalink)
Padowan Proper Boffin Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Kent, UK. Posts: 518	Re: VR3 Bailout question Quote: (Originally Posted by Mdemon) I wonder how confused a 4th cell VR£, plugged in and on CCR deco, would become if you went SCR? It wouldn't get confused. It would track the PPO2 of the loop and base it's deco on that fluctuating PPO2. The predicted TTS would be all over the shop, and would increase and decrease as the PPO2 fluctuated, but the rate that the stops that were proposed counted down would be a direct function of the changing PPO2. __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
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