Source for 20 foot LP hose / in water oxygen Deco

[Raphus]

Thoughtful information, thanks. The reason of course for the shallower deco/safety stops at altitude is due to the less than 1ata at the surface once you surface....interesting twist if I took it as you described above...deeper use of 100% oxygen at deco/safety stop will indeed widen/increase the Oxygen Window and give greater protection against symptomatic or asymptomatic bubbling/tissue damage. Greater [deeper] the gradient with oxygen the greater the reduction of DCS; higher oxygen tensions short of acute oxygen toxicity the higher the benefit. Still TODs and altitude tables key to the reduced atm pressure once you surface, so doing deeper deco stops is a no no and if breathing oxygen it may or may not fit the tables. Sticking to deco/safety stop depths published [your choice which tables] for surface altitudes but breathing 100% oxygen at these stops gives the greatest benefit; as you say a 'win-win'. Assuming you are diving within NDL, there will only be a single "deco" stop at the prescribed "safety stop" depth. One in the same.

As an aside, 1.6ata limit on 100% oxygen is a very conservative pressure limit. But I intend to adhere to it; remember chamber treatments [Tables 4 and 6 for example] often use 100% oxygen from bibs for 20-25mins at 60fsw pressure with 5 min air breaks in between repeated oxygen periods. I am not recommending going anywhere near 4ata used in chamber; but depending on the individuals oxygen tolerance there was a long time past practice of limiting 100% oxygen to 2ata. Read some of the pioneer diver Hans Hass's oxygen rebreather adventures; way beyond my comfort zone but enlightening.

Also important to not mix recompression protocols with decompression protocols. As a solo diver decompression is my only option [every dive ascent is a decompression event] and any recompression treatment will be after the fact in a chamber.

Now any recommendations out there for a vendor selling 100% oxygen dive regulators and tank valves, valves that commercial gas companies will fill with 100% oxygen? Thanks.

Ha! Just saw the best way to protect my 'old bod' is to limit the nitrogen load....I agree and I will do that with the extra protection when using 100% oxygen as described...but you know staying shallow does not have the allure of going deep! I will trade off BT for Z.


DSO

I will not jump into the discussion.
Just one warning, because you said something which is a common misunderstanding.

Comparing PO2 while diving with PO2 in a chamber. It cannot be compared, because the CO2 loading is greater while diving. CO2 increases oxygen toxicity. That's why 1.6 is the maximum while diving and in a chamber it's much larger (I think 2.8?).

1.6 is not conservative. Its a function of time and pressure. 1.6 can absolutely lead to damage of the lungs and cns. I personally know 2 divers, who had huge(!) problems on 1.6.

Please don't underestimate the dangers of oxygen while diving.



For the setup part.. get certified and dive with a small oxygen stage. It's not uncommon for aged recreational divers to do their safety stop on oxygen. If you have problems getting the fills, because the shop is far away. Get a big tank and transfill to the stage. Correct certificate and equipment required of course..

 

[Wallowa]

Good options and appreciated.. I especially like the terminology of "as a prophylactic for recreational diving." that really describes the value of using 100% oxygen at your safety stop....only me, so no manifold or extra second stages needed.. since I will not be diving from a boat a large oxygen cylinder is not an option...I will only need 5+ minutes of oxygen at 20 feet or less...so a small bottle inside my tube float will suffice...still not certain of how rig to tank and valve to accept the 20 ft LP hose and still be a valve/bottle combo that I can get refilled at a commercial station [not a dive store]...CGA540 is the standard but can I fit it to a small tank...

Oxygen concentrators and other means of filling my bottles with 100% or high % of oxygen is just way more hassle than I need...KISS...will not be using a lot of gas and filling commercially is much easier and fits my needs..

Again, my set-up will have zero to do with exceeding the NDL and required decompression stop or stops...only an adjunct to good diving practices that will help wash out as much nitrogen as possible before surfacing at altitude or SL..

Not the best but a good review of the mechanism and logic behind 100% oxygen on my safety stop: Oxygen window - Wikipedia

Thanks again for the advice and experiences...

DSO

 

[-JD-]

Standard Mixing Whip

john@northeastscubasupply.com

northeastscubasupply.com

 

[Wallowa]

I will not jump into the discussion.
Just one warning, because you said something which is a common misunderstanding.

Comparing PO2 while diving with PO2 in a chamber. It cannot be compared, because the CO2 loading is greater while diving. CO2 increases oxygen toxicity. That's why 1.6 is the maximum while diving and in a chamber it's much larger (I think 2.8?).

1.6 is not conservative. Its a function of time and pressure. 1.6 can absolutely lead to damage of the lungs and cns. I personally know 2 divers, who had huge(!) problems on 1.6.

Please don't underestimate the dangers of oxygen while diving.



For the setup part.. get certified and dive with a small oxygen stage. It's not uncommon for aged recreational divers to do their safety stop on oxygen. If you have problems getting the fills, because the shop is far away. Get a big tank and transfill to the stage. Correct certificate and equipment required of course..

Thanks Raphus....you are correct that CO2 levels can off-set the oxygen window benefit, that is why exercise/activity on a strenuous dive can be an issue....as for 1.6ata being a function of time and pressure...the pressure is 1.6ata will not be an issue, except in those with low oxygen tolerances, and cause acute/convulsions oxygen toxicity ....if the "time" under 1.6ata on oxygen is extended then "chronic oxygen toxicity" does become an issue....but I do not know of any diving other than perhaps habitats when a diver will remain underwater long enough for the chronic pulmonary problems from chronic oxygen toxicity...

Carrying or setting up a stage bottle would not work for me....solo means solo...no idea what certification you are referring to for using in water oxygen? Do appreciate your input and not knocking your ideas.

DSO

 

[Still Kicking]

I will not jump into the discussion.
Just one warning, because you said something which is a common misunderstanding.

Comparing PO2 while diving with PO2 in a chamber. It cannot be compared, because the CO2 loading is greater while diving. CO2 increases oxygen toxicity. That's why 1.6 is the maximum while diving and in a chamber it's much larger (I think 2.8?).

1.6 is not conservative. Its a function of time and pressure. 1.6 can absolutely lead to damage of the lungs and cns. I personally know 2 divers, who had huge(!) problems on 1.6.

Not to mention toxing in a chamber - with or without supervision - is far, far less risky than toxing underwater.

 

[rx7diver]

... so a small bottle inside my tube float will suffice...still not certain of how rig to tank and valve to accept the 20 ft LP hose and still be a valve/bottle combo that I can get refilled at a commercial station [not a dive store]...CGA540 is the standard but can I fit it to a small tank ...

You prefer a small oxygen cylinder that can be filled at other than a scuba shop, with the intention of leaving it floating on the surface in the basket attached to your dive float/inner tube. Okay:

Since you're DAN Emergency Oxygen certified (I'm assuming), can you get medical oxygen cylinders filled or exchanged easily enough? If so, then can't you simply use the approach that @happy-diver showed up-thread (that uses an adapter to connect a scuba first stage to a medical oxygen CGA870 post/pillar valve)? Medical oxygen bottles can be had in many sizes.

A good (oxygen service) first stage should be able to drive a 2nd stage attached via a 20 ft regulator hose without issue, I think.

However, the biggest potential problems I see with leaving a small cylinder on the surface in the basket attached to your dive float/inner tube are:

1. Will it still be there when you return from your dive-about?

2. You've left it "on", 20 ft above you, on the surface. What if it free-flows and empties while you're on your dive-about? What if it begins free-flowing while you're breathing off of it?

3. How will you prevent a casual swimmer or snorkeler from diving down and breathing off your 2nd stage and harming/killing himself/herself? A cave diver will drop his/her oxygen deco bottle a bit into the cave, where it's unlikely that a casual swimmer or snorkeler/free-diver will be able to access it.

4. (More)

rx7diver

 

[johndiver999]

The OP wants to keep it simple, but is making it way more complicated than it needs to be.

Buy rent or whatever, a large bottle of oxygen. Buy a 13-cu-ft pony bottle - it should come clean for oxygen service. Buy a cheap oxygen regulator with a gauge. Buy the proper hardware to transfill the oxygen from the big tank to the pony bottle. Wear the pony bottle as a stage clipped to your side and learn how to rig a stage bottle, so you don't get second stages mixed up and hit the oxygen at 60 feet and die alone.

It sounds like you are pulling a surface float all the time, so you should be able to wind yourself up under the float and use the string/tether to ensure that you decompress on oxygen at the proper depth. This is critical in my opinion.

Towing around a regulator on a 20 ft hose is a cluster, and if you do decide to do that, you are gonna want an inline shut off valve located at the second stage or you will be vulnerable to freeflows.

 

[NW Dive Dawg]

I just returned from Little Cayman and ALL of their boats have a 2nd stage on a 20ft hose hanging at 15ft for anyone needing that as an option. What is the downside of having that option be 100% O2? I will be diving for Lingcod tomorrow and even though I don't plan on DECO......what.... if any.... downside is there to breathing 100% O2 at 15 ft for 5 minutes prior to surfacing.

I have that option on my personal boat and anyone who feels that it is not for them can feel free to not use it.

PS..... Having a weighted 2nd stage on long hose at 15ft is way better than having a tank with a short hose hanging at 15ft. Mainly because if surface conditions are rough then who wants to a bucking tank in their face at 15 ft.

 

[Wallowa]

I just returned from Little Cayman and ALL of their boats have a 2nd stage on a 20ft hose hanging at 15ft for anyone needing that as an option. What is the downside of having that option be 100% O2? I will be diving for Lingcod tomorrow and even though I don't plan on DECO......what.... if any.... downside is there to breathing 100% O2 at 15 ft for 5 minutes prior to surfacing.

I have that option on my personal boat and anyone who feels that it is not for them can feel free to not use it.

PS..... Having a weighted 2nd stage on long hose at 15ft is way better than having a tank with a short hose hanging at 15ft. Mainly because if surface conditions are rough then who wants to a bucking tank in their face at 15 ft.

Exactly Dive Dawg. You get it.

I was looking for gear configuration and vendor information, not approval or judgements...yes, if you read previous posts, I taught DAN Oxygen Provider classes to hundreds of students and yes I have more than a passing knowledge of diving physics and diving safety protocols......remember that was my profession.

Folks....this has been real, but no more from me....negativity ruins dialogues and I will neither indulge it or participate in it ..bye...stay safe and enjoy your time underwater. Out here.

DSO