[PSUBS-MAILIST] onboard gear

Tue Apr 23 00:21:45 EDT 2019

What about using a EAN50 for the second gas? 

You can start pulling it at 70 ft which would give more latitude on the minimum operating depth of the first gas. 

At 70ft you can still safely breath a 6% O2 bottom gas which provides a better safety margin. 

Just running some numbers for gas quantities...

At a depth of 400 fsw, a normal, relaxed diver would consume around 9 CFM.

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On Tue, Apr 23, 2019 at 12:02 AM -0400, "TOM WHENT via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:

Very well said Sean. 

I do have some thought on your last statement about choosing decompression sickness.  I wonder,  if DCS would even be a consideration at all in that situation. My reasoning is that prior to escape the sub environment would be at surface pressure of 1 ATA, so there should be no onboarding of inert gas until the equalization and escape occurs. There may not be enough time to absorb enough inert gas into the body tissue to cause DCS. The rate of ascent might be an issue.

The greatest concern, in my opinion would be using a gas which may cause loss of consciousness at or near the surface. There is far less mystery to that and too many have died by breathing their bottom gas too shallow. Recently in my area an experienced rebreather diver died never having exceeded 7ft depth after taking a breath of his hypoxic bottom bailout gas to verify its operation.

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On Mon, Apr 22, 2019 at 11:41 PM -0400, "TOM WHENT via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:

Some people have taken air to extreme depths and some have perished doing so. 

Sheck Exley's book Caverns Measureless to Man has some excellent examples of this. 

The generally accepted maximum oxygen exposure is 1.6 atmospheres of partial pressure.  This is generally considered safe for all. Above that it's a crap shoot. Oxygen toxicity is the sole reason air becomes toxic at 218 fsw. 

Some people tolerate oxygen toxicity better than others. It is also experienced differently while immersed as opposed to a hyperbaric chamber where tolerance is greater. 

It is also a time- dose relationship. The higher the partial pressure the shorter the exposure duration can be before effects might be experienced. 1.6 ATA of oxygen partial pressure can be sustained for 45 minutes as a single dose. (NOAA oxygen exposure tables ) 

The mechanism of ox tox centers around the formation of oxygen free radicals in the body. The body can naturally eliminate so many before it is overwhelmed and neurological damage occurs. That is my simplified understanding of it. 

The higher the oxygen exposure,  the more rapidly OFRs are formed and more quickly a person may be affected. 

As divers we stay within the safe known operating parameters and trust that is enough to keep us alive. 

Often when there is a fatality the cause of death for the authorities is drowning but usually some other factor caused that outcome. 

In your escape situation, your exposure time might be small enough to avoid disaster. I can't say!  I would think that any delay in getting equalized and out of the sub could be increasingly difficult and the stress could predispose to ox tox also. 

If it were me, I would want to set myself up for the greatest possibility of success. 

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On Mon, Apr 22, 2019 at 11:04 PM -0400, "Brian Cox via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:

There have been numerous successful escapes from around 150' depth.   And free divers have set records going close to 400' I believe.   
Tom,   does the fact that compressed air becomes toxic at 218 ft is solely because of oxygen toxicity?
 Great analysis  !
Brian

--- personal_submersibles at psubs.org wrote:

From: TOM WHENT via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] onboard gear
Date: Mon, 22 Apr 2019 20:24:42 -0600 (MDT)

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As a rebreather and technical diver and gas blending technician I feel qualified to comment on this. 

Heliox 16 would be a poor choice due to expense and O2 content that is borderline at the surface. It would be toxic at 350 ft depth when inspired under ambient pressure and could produce a seizure without warning. 

Most deep divers would use a trimix gas of nitrogen , oxygen and helium in varying percentages to sustain life and avoid narcosis. It would have to be tailored specifically for the maximum depth as well as take into consideration your intended purpose of breathing it to the surface. 

The trouble is that oxygen becomes toxic when breathed at elevated partial pressures and the first warning of this could be a seizure. Generally these are not survivable when submerged on scuba. Cause of death is inevitably drowning.

Without getting too deep into the gas laws governing this,  what this means to you is that for dives of this depth one gas mix is not sufficient. For example a safe oxygen mix at 350ft would contain 13% oxygen or less. The problem arises when ascending to the surface because 13% oxygen will produce unconsciousness there. This is because of the reduced partial pressure from lower ambient pressure which affects the ability to transport oxygen into the body.. 

In the technical diving world we cross this bridge in one of two ways. 

1) using separate cylinders of gas for different phases of the dive... ie travel mix and bottom mix (deco mix also but this would be irrelevant to this discussion)

2) using a closed circuit rebreather which blends the gas on- the-fly to maintain optimal oxygen partial pressure for the depth. These are very expensive and require far more training than open circuit scuba.

I don't have an easy solution to your problem,  but can say that when escaping from that depth, you cannot safely use the same breathing gas without exposing yourself to extreme risk of drowning.

16 percent oxygen is considered the minimum  to sustain life at the surface and can be used safely to a depth of 297 fsw (or 10 atmospheres.)

An acceptable level of narcosis would be achieved by augmenting this with 57% helium, leaving the balance as nitrogen (27%)

The narcosis benchmark used would be an 80 ft depth equivalent exposure using air. 

Realistically 300ft is the deepest you would want to go with one gas, and even that is not ideal. Beyond that all bets are off. 

Something else to consider is that in a bailout situation, your ambient breathing air inside the sub could become toxic as pressure inside is increased to equalize to ambient pressure. You would need to be breathing your escape gas at that point.  Compressed air becomes toxic at a depth of approximately 218 ft.

I hope this helps! \uD83E\uDD2A

If you have any questions of this nature,  I'll do my best to help. 

Tom

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On Mon, Apr 22, 2019 at 8:58 PM -0400, "Alan via Personal_Submersibles" <personal_submersibles at psubs.org> wrote:

Sean,Yes, I'd rather make it to the surface than die intoxicated in the sub.I think every sub would have to develop their own equations for escapingat varying depths. The k250s & 350s could formulate a best scenario forescape for those classes of submersibles.Also in the equation is how fast you'd make it to the surface. A conventionallife jacket would crush at a decent depth, the inflatable ones wouldn'tInflate much against the water pressure.We have previously discussed drogues that are harnessed under your armsand provide air for breathing, but that's only a solution for 1 passenger.Alan
On 23/04/2019, at 12:30 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Does that mean that using something like heliox 16 to alleviate the narcosis at the elevated risk of a bends hit is an acceptable compromise? I'd rather be bent at the surface than narced to the extent that I'm unable to leave the bottom.

Sean

-------- Original Message --------
On Apr 22, 2019, 17:37, Alan via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
Also in this equation is the diminishing pressure of the water comingthrough the flood valve because of the compression of the air in the sub.Phil advised to turn on compressed air to hurry the equalisation requiredto open the hatch, as the water flow in to the sub slows right down towardthe end. Also he advised that getting out at over 300ft is near impossibledue to nitrogen narcosis leaving you so drunk that you can't get out anyway.Alan
On 23/04/2019, at 7:36 AM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Greg Cottrell once pointed out something that had been non-obvious to me in connection with bailouts from shallow-diving subs like ours - just how big the seacock needs to be to flood the sub quickly enough. Imagine you had a little ball valve of about the diameter of a garden hose. Now lets say you are hung up at 140 feet and need to bail. The ambient pressure is 60 psi, which happens to be the normal pressure for household plumbing. Therefore, your sub would take as long to fill up as it would if you opened the hatch while it was parked on your driveway and stuck the garden hose in. I'm not sure how long that is, and it will depend on the volume of your cabin, but surely it's way past the 10 minute no-decompression time for 140 feet. The bottom line is PSUB seacocks need to be very generously sized because we dive shallow. Shackleton's is 3". 
Best,Alec  
On Mon, Apr 22, 2019 at 2:39 PM Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Shanee
Depending on the depth that you have to flood the sub and make a free accent to the surface, it really depends on how fast you need to equalize to try and get to the surface before exceeding the nitrogen uptake limits for getting bent on course. Only the air cavity's are affected in a rapid pressurization I believe but my sub has a rated working depth of 350' and as I remember from the old navy tables, you only have about 5 minutes at 165' before you have to make a stop at 10' so due to that fact, I would have to flood the sub as fast as I can to minimize the nitrogen uptake to make it to the surface before getting bent and the negatives to that are that most people can't clear their ears that fast so you are looking at possibly blowing your ear drums which in turn is really painful and screws up you equilibrium which is going to hamper your safe accent to the surface in a timely manner. I am going to have mixed gas in my bailouts to buy me time for getting to the surface and keeping the nitrogen uptake as minimal as possible.Rick
On Mon, Apr 22, 2019 at 7:15 AM Shanee Stopnitzky via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Doesn't feel like it compared to Hank! Also, forgetting food, water, blankets and a first aid kit. Forgetting those has been my specialty for my whole life!
Steinke hoods are probably a good idea, although I'm terrified of them myself. Does anyone have any information on what pressure change effects happen physiologically during an emergency escape? I'm a diver so I'm very familiar with what happens when you descend and ascend on scuba, but I'm not sure what happens with a sudden and extreme pressure increase. Other than all your organs getting squished, of course. 
Thanks for your input everybody!
On Sun, Apr 21, 2019 at 6:58 PM Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Hi Shanee,
That's a pretty comprehensive list you have, and I couldn't fit all that. But how about a pair of Steinke hoods? Oh, and one very simple thing... a flashlight.
Best,Alec
On Sun, Apr 21, 2019 at 4:35 PM Shanee Stopnitzky via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Hi all,
I'm wondering what everyone's onboard safety/repair kits contain, or what 'loose' gear you carry on dives with you. Ours are (so far): 
CG requirementsair hornwhistlelife jacketsfire extinguisher
safetyfire blanket2x scuba masks2x spare airprimary gas analyzerbackup gas analyzerspare CO2 scrubber - battery poweredhandheld radiosuw radio system
repair kitgorilla tapeelectrical tapebutyl tapezip tie assortmentspare battery terminalsspare wire connectorsspare wiresplash zoneJB weldsteel tie wiresteel strape6000 glue hose clamp assortmentscrewdriver setadjustable wrenchmulti-toolhammerscissors
What's in your kits?
Best,Shanee
-- 
Institute for Emergence//Community Submersibles Project
:::::

'The fact remains that political frontiers are impervious to our verbal cultures, while the substantially nonverbal civilization of playfulness crosses them with the happy freedom of the wind and the clouds.' ~ Primo Levi 
:::::
'Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more-than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth. Our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of wolves and the honking of geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. ' ~David Abrams
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-- 
Institute for Emergence//Community Submersibles Project
:::::

'The fact remains that political frontiers are impervious to our verbal cultures, while the substantially nonverbal civilization of playfulness crosses them with the happy freedom of the wind and the clouds.' ~ Primo Levi 
:::::
'Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more-than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth. Our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of wolves and the honking of geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. ' ~David Abrams
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Sean,Yes, I'd rather make it to the surface than die intoxicated in the sub.I think every sub would have to develop their own equations for escapingat varying depths. The k250s & 350s could formulate a best scenario forescape for those classes of submersibles.Also in the equation is how fast you'd make it to the surface. A conventionallife jacket would crush at a decent depth, the inflatable ones wouldn'tInflate much against the water pressure.We have previously discussed drogues that are harnessed under your armsand provide air for breathing, but that's only a solution for 1 passenger.Alan
On 23/04/2019, at 12:30 PM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Does that mean that using something like heliox 16 to alleviate the narcosis at the elevated risk of a bends hit is an acceptable compromise? I'd rather be bent at the surface than narced to the extent that I'm unable to leave the bottom.

Sean

-------- Original Message --------
On Apr 22, 2019, 17:37, Alan via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
Also in this equation is the diminishing pressure of the water comingthrough the flood valve because of the compression of the air in the sub.Phil advised to turn on compressed air to hurry the equalisation requiredto open the hatch, as the water flow in to the sub slows right down towardthe end. Also he advised that getting out at over 300ft is near impossibledue to nitrogen narcosis leaving you so drunk that you can't get out anyway.Alan
On 23/04/2019, at 7:36 AM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

Greg Cottrell once pointed out something that had been non-obvious to me in connection with bailouts from shallow-diving subs like ours - just how big the seacock needs to be to flood the sub quickly enough. Imagine you had a little ball valve of about the diameter of a garden hose. Now lets say you are hung up at 140 feet and need to bail. The ambient pressure is 60 psi, which happens to be the normal pressure for household plumbing. Therefore, your sub would take as long to fill up as it would if you opened the hatch while it was parked on your driveway and stuck the garden hose in. I'm not sure how long that is, and it will depend on the volume of your cabin, but surely it's way past the 10 minute no-decompression time for 140 feet. The bottom line is PSUB seacocks need to be very generously sized because we dive shallow. Shackleton's is 3". 
Best,Alec  
On Mon, Apr 22, 2019 at 2:39 PM Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Shanee
Depending on the depth that you have to flood the sub and make a free accent to the surface, it really depends on how fast you need to equalize to try and get to the surface before exceeding the nitrogen uptake limits for getting bent on course. Only the air cavity's are affected in a rapid pressurization I believe but my sub has a rated working depth of 350' and as I remember from the old navy tables, you only have about 5 minutes at 165' before you have to make a stop at 10' so due to that fact, I would have to flood the sub as fast as I can to minimize the nitrogen uptake to make it to the surface before getting bent and the negatives to that are that most people can't clear their ears that fast so you are looking at possibly blowing your ear drums which in turn is really painful and screws up you equilibrium which is going to hamper your safe accent to the surface in a timely manner. I am going to have mixed gas in my bailouts to buy me time for getting to the surface and keeping the nitrogen uptake as minimal as possible.Rick
On Mon, Apr 22, 2019 at 7:15 AM Shanee Stopnitzky via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Doesn't feel like it compared to Hank! Also, forgetting food, water, blankets and a first aid kit. Forgetting those has been my specialty for my whole life!
Steinke hoods are probably a good idea, although I'm terrified of them myself. Does anyone have any information on what pressure change effects happen physiologically during an emergency escape? I'm a diver so I'm very familiar with what happens when you descend and ascend on scuba, but I'm not sure what happens with a sudden and extreme pressure increase. Other than all your organs getting squished, of course. 
Thanks for your input everybody!
On Sun, Apr 21, 2019 at 6:58 PM Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Hi Shanee,
That's a pretty comprehensive list you have, and I couldn't fit all that. But how about a pair of Steinke hoods? Oh, and one very simple thing... a flashlight.
Best,Alec
On Sun, Apr 21, 2019 at 4:35 PM Shanee Stopnitzky via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
Hi all,
I'm wondering what everyone's onboard safety/repair kits contain, or what 'loose' gear you carry on dives with you. Ours are (so far): 
CG requirementsair hornwhistlelife jacketsfire extinguisher
safetyfire blanket2x scuba masks2x spare airprimary gas analyzerbackup gas analyzerspare CO2 scrubber - battery poweredhandheld radiosuw radio system
repair kitgorilla tapeelectrical tapebutyl tapezip tie assortmentspare battery terminalsspare wire connectorsspare wiresplash zoneJB weldsteel tie wiresteel strape6000 glue hose clamp assortmentscrewdriver setadjustable wrenchmulti-toolhammerscissors
What's in your kits?
Best,Shanee
-- 
Institute for Emergence//Community Submersibles Project
:::::

'The fact remains that political frontiers are impervious to our verbal cultures, while the substantially nonverbal civilization of playfulness crosses them with the happy freedom of the wind and the clouds.' ~ Primo Levi 
:::::
'Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more-than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth. Our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of wolves and the honking of geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. ' ~David Abrams
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-- 
Institute for Emergence//Community Submersibles Project
:::::

'The fact remains that political frontiers are impervious to our verbal cultures, while the substantially nonverbal civilization of playfulness crosses them with the happy freedom of the wind and the clouds.' ~ Primo Levi 
:::::
'Caught up in a mass of abstractions, our attention hypnotized by a host of human-made technologies that only reflect us back to ourselves, it is all too easy for us to forget our carnal inherence in a more-than-human matrix of sensations and sensibilities. Our bodies have formed themselves in delicate reciprocity with the manifold textures, sounds, and shapes of an animate earth. Our eyes have evolved in subtle interaction with other eyes, as our ears are attuned by their very structure to the howling of wolves and the honking of geese. To shut ourselves off from these other voices, to continue by our lifestyles to condemn these other sensibilities to the oblivion of extinction, is to rob our own senses of their integrity, and to rob our minds of their coherence. ' ~David Abrams
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There have been numerous successful escapes from around 150' depth.   And free divers have set records going close to 400' I believe.   
Tom,   does the fact that compressed air becomes toxic at 218 ft is solely because of oxygen toxicity?
 Great analysis  !
Brian

--- personal_submersibles at psubs.org wrote:

From: TOM WHENT via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] onboard gear
Date: Mon, 22 Apr 2019 20:24:42 -0600 (MDT)