Regulator for tec

[Angelo Farina]

@Angelo Farina Let me preface by saying I'm not an experienced deco diver, but the way I understand it is that bubbles form because of the pressure gradient between the pressure in your tissues vs the ambient pressure. If you replace the nitrogen content of the air you breath with oxygen instead, the pressure gradient stays the same, and therefore bubble formation is not impacted.

The reason why accelerated deco works is that your offgassing rate is dependent on the pressure gradient of the dissolved gas in your tissues vs the inert pressure of the gas in your bloodstream. If you replace nitrogen with oxygen, that gradient will increase and therefore make you offgas faster with the same bubble formation.

Regarrding your second point, I get that some tissues are slower because there is less blood flowing through them. Regardless, the rate of offgassing should still increase when you breath a higher ppo2 mixture, right? You

These are standard assumption employed for computing reduced deco times thanks to high PPO2.
I always found this a too simple model of the human body. And those physical gas laws are certainly close to reality in a lab, but inside human body things can deviate from these laws.
As a general rule, when you try to make something running faster, there are always drawbabks.
My point is that we do not know enough of what's really happening, and relying on a simplified model is too risky for me.
So if you give me 50% nitrox for deco I breath it very happily, but I stll make the same deco times as with air.
This way I am sure to be on the safe side, instead of playing russian roulette with my life just for saving 10 minutes of deco time.

 

[BoltSnap]

The more accelerated, the less safe.
There are a number of factors pointing in this direction:
1) the amount of Nitrogen you have to release before being able to surface is given by the dive profile, so it is fixed when you begin the deco. If the deco is shorter, the flow rate of Nitrogen through your body and veins is necessarily higher. And this increases the risk that there are large bubbles, which can be trapped somewhere.
2) usually DCS is caused by your "critical" tissue, the one where Nitrogen has been stored with larger concentration. Such a tissue is not necessarily in direct connection with your blood, so he could not "know" that you are breathing pure oxygen. In almost all the mathematical models employed for calculating deco times, each tissue releases the excess Nitrogen at a rate proportional to the difference between the partial pressure inside the tissue and the partial pressure of the gas in your lungs. But this is true only if all these tissues "see" what is in your lungs. Some tissues are very far from them, in between there are other tissues which possibly trapped little Nitrogen, but are acting as a filter between the critical tissue and your blood-lungs. So these critical tissues will degas with the same speed as if you was breathing air, and you risk to not wait enough time at deco stops for degassing it properly. It is a remote risk, but why taking it?
3) And finally, carrying with you a deco tank containing a mixture with high PPO2 can be very dangerous if that mixture is breathed at depth, causing oxygen toxicity.
For these reasons I never reduce my deco times when enriched air or pure oxygen is available for deco. I always consider to be breathing air. And I never carry enriched-air deco tanks at depth, I consider them only as an useful additional resource if deployed by the boat attached to the deco bar when they see the divers approaching the surface.

What are your references in the narrative you bring out above to support your argument against using higher O2% in deco gas?

 

[BoltSnap]

Located in the philippines. I ve thought of the deep6 but i dont have the means to go get a deep6 maintenance class, no deep6 dealers here too

Scubapro is the LARGEST vendor in the world for regulators used in technical diving with distribution channel spanning the entire world where there is organized diving. It is also a well established company with plenty of financial stability and is a very healthy company to support its dealers and end users. SP's regulators are top notch performers with high level of reliability. Other small time fragile companies that are owned by few individuals who don't have the resources and international dealer network are usually a big gamble and I don't see it as a wise investment.

 

[BoltSnap]

Hes i realized going tec isnt going to be cheap. The tech class isnt immediate were rounding up buddies who wants in. Were being guided by a tech diver in our group. Hes all alone now as tech diver after his tech buddies moved to other locations. Hope fully wel be able to attend basic tech by end of the year. Were slowly getting the list of stuffs we need slowly. It gets quite expensive to get everything at 1 time. I live in a ccountry that has diving in the backyard. If we get our own boat and rent our own tanks without the dive package, we can easily dive for say 2 dives 30$ and thats including lunch lol. Iv had most of my first 100 dives this way. We had a padi divemaster buddy who just wanted to dive. He taught us a lot of things. There were 3 of them. Now theyve migrated to different countries. Weve decided to reactivate the group . So a couple of us padi rescue, are racking up experience for the newbies ..... hopefully theyl go tech too

If you need to get connected with a top notch technical instructor in your area, please let me know. I somebody who is highly trained and qualified and is one of the top instructor for the Philippine special forces. He teaches technical diving on regular basis all over the Philippines.

 

[BoltSnap]

These are standard assumption employed for computing reduced deco times thanks to high PPO2.
I always found this a too simple model of the human body. And those physical gas laws are certainly close to reality in a lab, but inside human body things can deviate from these laws.
As a general rule, when you try to make something running faster, there are always drawbabks.
My point is that we do not know enough of what's really happening, and relying on a simplified model is too risky for me.
So if you give me 50% nitrox for deco I breath it very happily, but I stll make the same deco times as with air.
This way I am sure to be on the safe side, instead of playing russian roulette with my life just for saving 10 minutes of deco time.

It is also FAR better for the OP to seek a qualified technical diving instructor who has the expertise and skill to give proper instructor and advice on how to handle technical diving including all of the various issues and options for deco and deco gases than to try to go with advice based on personal opinion here. Is this is a very dangerous activity where one should relay on an expert who can be held accountable for his advice.

 

[Degenerate]

I'd suggest you forget SP if you're going tec. Get HOG or Deep Six. Going tec it's likely that you'll wind up with way more than 3 regs and you'll want to be able to service them yourself.

I'm sorry, forget Scubapro if you're going tech, what..?
You can easily service Scubapro regs yourself, and there is no way you can make a good argument against their regs, the Mk25/G250v is an incredible combo with awesome hose routing for doubles...

 

[LanceRiley]

If you need to get connected with a top notch technical instructor in your area, please let me know. I somebody who is highly trained and qualified and is one of the top instructor for the Philippine special forces. He teaches technical diving on regular basis all over the Philippines.

We were planning to fly in a gue instructor... but hey im open to suggestions.
The tech guy we dive with recreationally is gue

 

[loosenit2]

Scubapro is the LARGEST vendor in the world for regulators used in technical diving with distribution channel spanning the entire world where there is organized diving. It is also a well established company with plenty of financial stability and is a very healthy company to support its dealers and end users. SP's regulators are top notch performers with high level of reliability. Other small time fragile companies that are owned by few individuals who don't have the resources and international dealer network are usually a big gamble and I don't see it as a wise investment.

You are making a pretty bold value judgement. You are right that Scubapro is the largest vendor in the world and their products are excellent but that comes at a cost premium, both in initial cost and maintenance costs. Scubapro, more than any other vendor, designs their equipment to require the use of scubapro specific special tools and they are very closed about selling parts and tools to other than LDSs. There are others that are challenging this model, and with good cause. Other industries have moved away from the sell only through local shops model because of the internet. Deep6, DGX, and HOG come to mind as challengers with products that are at least as good if not having the same worldwide support network.

 

[MichaelMc]

OP:

Yes we dive 40meters on single tank with a bit of cave. Dont worry its a small cave. Probably just 20m inwards.

Sounds rather extreme.
40m down, 20m in, just a bit of cave, single tank, while just starting to consider tech, much less completed cavern/cave
is rather outside the recommendations. I would consider more carefully where your tech friend is leading you. And how soon.

All the Scuba Pro is world wide and great and others are risky bit. SP makes good stuff. So do others.

While I'm commenting, SP makes a sealed turret MK19 that is not available in the US but might be where you are. Others with sealed turrets are Apeks, Deep6, DiveRite, Hog. You do not need sealed for cold where you are, but it keeps grit and salt out as well, simplifying maintenance worries.

 

[LanceRiley]

OP:

Sounds rather extreme.
40m down, 20m in, just a bit of cave, single tank, while just starting tech, much less starting cave
is rather outside the recommendations. I would consider more carefully where your tech friend is leading you.

All the Scuba Pro is world wide and great and others are risky bit. SP makes good stuff. So do others.

While I'm commenting, SP makes a sealed turret MK19 that is not available in the US but might be where you are. Others with sealed turrets are Apeks, Deep6, DiveRite, Hog. You do not need sealed for cold where you are, but it keeps grit out as well, simplifying maintenance worries.

Oh dont get me wrong. It wasnt a tech thing. And he did say it was not in any regulations in any diving school of thought.

As locals we do this a lot. Albeit short dive.

We have this cave with markers of divers that have died.. occassionally we visit that cave. 40m is the base Or ground of the cave. Height of cave mouth is 10m.i approached in the middle somewhere between 33m ... but the floor slopes up. You.ll still end up 30m while diving inside.

no dive shops wont bring you to this cave unless it was a tec dive. This site is frequented by locals only