Think piece: rebreather breathing on the surface

warjarrett · 16th October 2007, 21:28

Are there dangers in breathing closed-circuit at the surface, that are greater than at depth? What is the concern, and why is it a bigger problem at the surface?

womble · 16th October 2007, 21:57

Quote: (Originally Posted by warjarrett)

Are there dangers in breathing closed-circuit at the surface, that are greater than at depth? What is the concern, and why is it a bigger problem at the surface?

Breathing hypoxic diluents (<16% o2) at the surface with the O2 not turned on can be fatal, whereas at depth the rise in PPO2 will keep you alive, BUT ONLY IF YOU CONTINUALLY FLUSH THE LOOP WITH DIL (ie open loop or SCR)

Flushing the loop on the surface wont do anything as your PPO2 will still only be <0.16, not enough to sustain life.

If you dont flush the loop at depth, and your O2 is off, this will be just as fatal.

HTH

Gilles · 16th October 2007, 22:48

Also if you don't have one of those adaptive algorithm solenoids, each shot of O2 the solenoid gives you, lasts less time on the surface than at depth. You're also susceptible to the conditions at surface (current, waves, etc causing higher consumption).

IMV, being at near surface (or very beginning) is just as dangerous as say,.. a 50m+ deco dive. Worse if you're unnecessarily using hypoxic diluents.

Dave & Sandy · 17th October 2007, 02:58

Are you a school teacher as your think pieces sound like exam questions. Just wondering how many marks for each of the two questions.

Drmike · 17th October 2007, 03:05

Quote: (Originally Posted by warjarrett)

Are there dangers in breathing closed-circuit at the surface, that are greater than at depth? What is the concern, and why is it a bigger problem at the surface?

I hope you know the answer to this question already.
If you dont know the answer to this you might want to consider if you are knowledgeable enough to be diving a rebreather - this is IMO fundamental stuff - have you done a course? was this not covered? perhaps you just forgot. If you really dont know then perhaps you should do your self and your family a favour and sell it or get some formal/better training before we read about another shallow water/surface rebeather death - hey you could be this months lucky winner! Hmm......Wonder who it will be that dies this month? The suspense is killing me (if you excuse the pun)

sorry for the rant - haven't had my morning cup yet - and am still bothered by the 1 death/month on rebreather thing. When I read a question such as this that is 'basic' being asked by a Rebreather diver I just think something is really wrong somewhere. Is it the training? students retention of facts? what is it?

Maybe you had a legitimate reason to ask this question and are aware of the answer in which case my apologies.

There was a good thread about this before here you may want to look up in the archives

bluedjango1 · 17th October 2007, 03:08

one of my closest friends and top anesthesiologists in Philly said this when discussing rebreathers, "rebreathers at 1 ATA are very simple... I have been using them for the past 20 years. Where it becomes complex is when we change the absolute pressure, that is the tricky part..."

ok, not an exact quote, but pretty close

are rebreathers tricky at the surface?

probably as tricky as anywhere else if you are not monitoring your loop...

Drmike · 17th October 2007, 03:23

Quote: (Originally Posted by bluedjango1)

when I had my shop outside of Philly, one of my closest friends and top anesthesiologists in the city said this when discussing rebreathers, "rebreathers at 1 ATA are very simple... I have been using them for the past 20 years. Where it becomes complex is when we change the absolute pressure, that is the tricky part..."

ok, not an exact quote, but pretty close

are rebreathers tricky at the surface?

how many of his patients struggle with gear, swim against currents and surface swells, climb moving ladders carrying heavy equipment, pull themselves along drag lines - whilst being treated?

How many of his patients are the ones in charge of monitoring and maintaining their ppo2 during treatment?

theres more going on on the surface and it can be quite an exersion - ppo2 drops faster on surface and theres often more task loading (think bad sea conditions, swells, heavy gear, fighting to pass up equipment, climb ladders etc - so you combine need for more frequent monitoring with a time of increased task loading....not a good combination! especially if you have a Rebreather with a crap setpoint controller or O2 turned off (has killed at least one) or RB not turned on (has killed another) At 150m depth even with O2 turned off and unit turned off the dil will keep you alive for yonks - on the surface you have very little time

bluedjango1 · 17th October 2007, 03:33

Quote: (Originally Posted by Drmike)

how many of his patients struggle with gear, swim against currents and surface swells, climb moving ladders carrying heavy equipment, pull themselves along drag lines - whilst being treated?

How many of his patients are the ones in charge of monitoring and maintaining their ppo2 during treatment?

theres more going on on the surface and it can be quite an exersion - ppo2 drops faster on surface and theres often more task loading (think bad sea conditions, swells, heavy gear, fighting to pass up equipment, climb ladders etc - so you combine need for more frequent monitoring with a time of increased task loading....not a good combination! especially if you have a Rebreather with a crap setpoint controller or O2 turned off (has killed at least one) or RB not turned on (has killed another) At 150m depth even with O2 turned off and unit turned off the dil will keep you alive for yonks - on the surface you have very little time

Mike... recognize the source, obviously a patient he was treating dealt with none of these, hence the reason I posted it

Drmike · 17th October 2007, 03:42

Quote: (Originally Posted by bluedjango1)

obviously a patient he was treating dealt with none of these,

obviously - hence his conclusion is irrelevant

bluedjango1 · 17th October 2007, 03:53

Quote: (Originally Posted by Drmike)

obviously - hence his conclusion is irrelevant

doubtful... if you are going to deal at only one atmosphere how will any of what you mentioned earlier be relevant in any way?

the military has been using it for years... at least our's has...

16th October 2007, 21:28	#1 (permalink)
warjarrett New Member Current Rebreather/s: Prism Topaz Other Rebreather/s: Join Date: May 2007 Location: Los Angeles Posts: 51	Think piece: rebreather breathing on the surface Are there dangers in breathing closed-circuit at the surface, that are greater than at depth? What is the concern, and why is it a bigger problem at the surface?
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16th October 2007, 21:57	#2 (permalink)
womble Custom Title Allowed! Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Aug 2006 Location: UK Posts: 188	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by warjarrett) Are there dangers in breathing closed-circuit at the surface, that are greater than at depth? What is the concern, and why is it a bigger problem at the surface? Breathing hypoxic diluents (<16% o2) at the surface with the O2 not turned on can be fatal, whereas at depth the rise in PPO2 will keep you alive, BUT ONLY IF YOU CONTINUALLY FLUSH THE LOOP WITH DIL (ie open loop or SCR) Flushing the loop on the surface wont do anything as your PPO2 will still only be <0.16, not enough to sustain life. If you dont flush the loop at depth, and your O2 is off, this will be just as fatal. HTH __________________ "What could possibly go wrong?? . . "
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16th October 2007, 22:48	#3 (permalink)
Gilles Worship the feminine Current Rebreather/s: Megalodon Other Rebreather/s: Join Date: Sep 2005 Location: Den Haag (Netherlands) Posts: 761	Re: Think piece: rebreather breathing on the surface Also if you don't have one of those adaptive algorithm solenoids, each shot of O2 the solenoid gives you, lasts less time on the surface than at depth. You're also susceptible to the conditions at surface (current, waves, etc causing higher consumption). IMV, being at near surface (or very beginning) is just as dangerous as say,.. a 50m+ deco dive. Worse if you're unnecessarily using hypoxic diluents. __________________ Gilles http://www.dirrebreather.com
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17th October 2007, 02:58	#4 (permalink)
Dave & Sandy New Member Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2006 Location: Melbourne, Australia Posts: 93	Re: Think piece: rebreather breathing on the surface Are you a school teacher as your think pieces sound like exam questions. Just wondering how many marks for each of the two questions. __________________ Cheers, Dave & Sandy Atvar shows Dave & Sandy testing their new habitat 101 and home build RBMK69's
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17th October 2007, 03:05	#5 (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: 3,128	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by warjarrett) Are there dangers in breathing closed-circuit at the surface, that are greater than at depth? What is the concern, and why is it a bigger problem at the surface? I hope you know the answer to this question already. If you dont know the answer to this you might want to consider if you are knowledgeable enough to be diving a rebreather - this is IMO fundamental stuff - have you done a course? was this not covered? perhaps you just forgot. If you really dont know then perhaps you should do your self and your family a favour and sell it or get some formal/better training before we read about another shallow water/surface rebeather death - hey you could be this months lucky winner! Hmm......Wonder who it will be that dies this month? The suspense is killing me (if you excuse the pun) sorry for the rant - haven't had my morning cup yet - and am still bothered by the 1 death/month on rebreather thing. When I read a question such as this that is 'basic' being asked by a Rebreather diver I just think something is really wrong somewhere. Is it the training? students retention of facts? what is it? Maybe you had a legitimate reason to ask this question and are aware of the answer in which case my apologies. There was a good thread about this before here you may want to look up in the archives __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 17th October 2007 at 03:38.
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17th October 2007, 03:08	#6 (permalink)
bluedjango1 New Member Current Rebreather/s: Other CCR Other Rebreather/s: Megalodon Other CCR Join Date: Jan 2007 Location: High Springs Posts: 34	Re: Think piece: rebreather breathing on the surface one of my closest friends and top anesthesiologists in Philly said this when discussing rebreathers, "rebreathers at 1 ATA are very simple... I have been using them for the past 20 years. Where it becomes complex is when we change the absolute pressure, that is the tricky part..." ok, not an exact quote, but pretty close are rebreathers tricky at the surface? probably as tricky as anywhere else if you are not monitoring your loop... __________________ Safe diving, Corey Last edited by bluedjango1 : 17th October 2007 at 03:14.
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17th October 2007, 03:23	#7 (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: 3,128	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by bluedjango1) when I had my shop outside of Philly, one of my closest friends and top anesthesiologists in the city said this when discussing rebreathers, "rebreathers at 1 ATA are very simple... I have been using them for the past 20 years. Where it becomes complex is when we change the absolute pressure, that is the tricky part..." ok, not an exact quote, but pretty close are rebreathers tricky at the surface? how many of his patients struggle with gear, swim against currents and surface swells, climb moving ladders carrying heavy equipment, pull themselves along drag lines - whilst being treated? How many of his patients are the ones in charge of monitoring and maintaining their ppo2 during treatment? theres more going on on the surface and it can be quite an exersion - ppo2 drops faster on surface and theres often more task loading (think bad sea conditions, swells, heavy gear, fighting to pass up equipment, climb ladders etc - so you combine need for more frequent monitoring with a time of increased task loading....not a good combination! especially if you have a Rebreather with a crap setpoint controller or O2 turned off (has killed at least one) or RB not turned on (has killed another) At 150m depth even with O2 turned off and unit turned off the dil will keep you alive for yonks - on the surface you have very little time __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you Last edited by Drmike : 17th October 2007 at 03:26.
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17th October 2007, 03:33	#8 (permalink)
bluedjango1 New Member Current Rebreather/s: Other CCR Other Rebreather/s: Megalodon Other CCR Join Date: Jan 2007 Location: High Springs Posts: 34	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Drmike) how many of his patients struggle with gear, swim against currents and surface swells, climb moving ladders carrying heavy equipment, pull themselves along drag lines - whilst being treated? How many of his patients are the ones in charge of monitoring and maintaining their ppo2 during treatment? theres more going on on the surface and it can be quite an exersion - ppo2 drops faster on surface and theres often more task loading (think bad sea conditions, swells, heavy gear, fighting to pass up equipment, climb ladders etc - so you combine need for more frequent monitoring with a time of increased task loading....not a good combination! especially if you have a Rebreather with a crap setpoint controller or O2 turned off (has killed at least one) or RB not turned on (has killed another) At 150m depth even with O2 turned off and unit turned off the dil will keep you alive for yonks - on the surface you have very little time Mike... recognize the source, obviously a patient he was treating dealt with none of these, hence the reason I posted it __________________ Safe diving, Corey
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17th October 2007, 03:42	#9 (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: 3,128	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by bluedjango1) obviously a patient he was treating dealt with none of these, obviously - hence his conclusion is irrelevant __________________ Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you
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17th October 2007, 03:53	#10 (permalink)
bluedjango1 New Member Current Rebreather/s: Other CCR Other Rebreather/s: Megalodon Other CCR Join Date: Jan 2007 Location: High Springs Posts: 34	Re: Think piece: rebreather breathing on the surface Quote: (Originally Posted by Drmike) obviously - hence his conclusion is irrelevant doubtful... if you are going to deal at only one atmosphere how will any of what you mentioned earlier be relevant in any way? the military has been using it for years... at least our's has... __________________ Safe diving, Corey
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