Don't breathe tanks to zero?

[eelnoraa]

I think we are over thinking here. If you breath the tank dry, take it to a dive shop for a VIZ and necessary cleaning if needed as soon as possible, then nothing will happen to the tank.

The issue here is that why would you need to breath the tank dry. You should never plan to breath it dry. If you find yourself breathing the tank dry on every dive, it is time to revisite your gas planning strategy. But if things happen, you need to breath down to 0psi in order to survive, then let it be.

 

[tracydr]

A 3 minute safety stop has been the norm for a long time, and that is what is usually taught in classes; however, there is a growing trend to do 5 minute stops instead. There is some research that supports this.

Do you have some references? I'd love to read the research. We could start a new thread.

 

[redacted]

IThe issue here is that why would you need to breath the tank dry. You should never plan to breath it dry. If you find yourself breathing the tank dry on every dive, it is time to revisite your gas planning strategy. But if things happen, you need to breath down to 0psi in order to survive, then let it be.

I guess we are just going to have to disagree. I believe everyone should plan a dive to breath their tank dry (or real close) so they will know how their gear performs under such circumstances. Had I not done that, I would not have know how well my 2nd stages performed as pressure dropped below IP or that one particular design of a 1st stage (Scubapro Mk7) essentially stops delivering breathable gas through the primary right ablout IP and I must switch to my secondary to access the rest of the gas in my tank.

What do your regulators do as your tank approaches empty?

 

[The Chairman]

I think we are over thinking here. If you breath the tank dry, take it to a dive shop for a VIZ and necessary cleaning if needed as soon as possible, then nothing will happen to the tank.

I disagree with this sentiment.

 

[chrpai]

I disagree with this sentiment.

I agree with that disagreement.

Although I'm not sure how many "basic" O/W divers have a transfill whip.

 

[boulderjohn]

Do you have some references? I'd love to read the research. We could start a new thread.

I was referring specifically to the research cited by DAN that compared ascent rates. A week or so ago I did a search of the DAN site, found what I wanted after a lot of looking, and posted it in another tread. I just tried to do it again and couldn't find it. I am about to close down my computer for a trip and don't have time to search more. I won't be back online for a while.

That ascent rate study compared 10 minute, 30 minute, and 60 minute ascent rates. They also included 5 minute stops in the study. The results indicated that the 30 feet/minute ascent rate was best , and the 10 feet/minute was worst. It also concluded that a 5 minute stop was more important than the ascent rates. As I read it, it seemed to me that the safety stop is apparently more important than it used to be thought.

I do not, however, know of research that specifically compares 3 minute stops with 5 minute stops.

 

[chrpai]

A 3 minute safety stop has been the norm for a long time, and that is what is usually taught in classes; however, there is a growing trend to do 5 minute stops instead. There is some research that supports this.

I do not, however, know of research that specifically compares 3 minute stops with 5 minute stops.

Didn't you just say there was?

Research aside, the dive sites I frequent allow me to consider the safety stop merely a transition from one portion of the dive to another. I frequently spend another 15 - 30 minutes slowly ascending from 20' to surface.

 

[The Chairman]

If you want to avoid being tired after a dive, do a deep stop and then a full five minute safety stop. As it turns out, neural fluids have about the same half time as blood. According to DAN, getting bent is pretty rare. However, if you are bent then, as a recreational diver, you will almost always have a type II DCS (neural). Doing a full five minute stop ameliorates the already small risk even further.

I do remember a caveat about doing a three to five minute stop, though I can't quite remember if it was my OW class or NitrOx. It specified that if you were diving a PDC that you should do a full five minute stop due to the fact that you are able to ride the NDL.

 

[Jon_R]

Topped with nitrogen? Kind of, not really though.

Curious, have you taken a nitrox class? It's called enriched air for a reason. Also I don't trust other people to analyze my gas for me. I'm breathing it, not them.

Yes I took the class. Not sure what it is blended with. Assume a mix with much lower o2 levels than what you have at the end since it is starting 100% o2. When I picked up the tanks I watched them hook them to the gauge and test them and saw the percent 02. I don't have my own gauge if that is what you mean.


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[eelnoraa]

Testing your reg at its limit isn't same as planning to dive it to its limit, by that I mean at empty tank. What happen to your buddy if he need air? If you plan your dive to empyt your tank, what are you going to do?

I guess we are just going to have to disagree. I believe everyone should plan a dive to breath their tank dry (or real close) so they will know how their gear performs under such circumstances. Had I not done that, I would not have know how well my 2nd stages performed as pressure dropped below IP or that one particular design of a 1st stage (Scubapro Mk7) essentially stops delivering breathable gas through the primary right ablout IP and I must switch to my secondary to access the rest of the gas in my tank.

What do your regulators do as your tank approaches empty?