double tank equipment

[agilis]

Obviosly, mixing between the two tanks takes place under the circumstances I outlined, probably primarily in the manifold. If mixing did not take place, what would be the point of having a communicating manifold?

The issue I was addressing initially had to do with the possibility of each separate tank having a different level of O2 when using nitrox. I understand that gas from one tank will not flow into the other unless there is a difference in pressure, and that there cannot be a pressure difference if the tanks are communicating.

On the other hand, if there is a pressure difference because the valve between them is closed there will indeed be a mixing of gases when the valve is opened. This is the situation that was described by a poster who had consequently called a dive under those circumstances, and to whose post I responded. Then you decided to stick your nose in for no valid reason, apparently motivated by that inflated ego.

Obviously, if the pressures in both tanks are equal, there will be little or no mixing in either tank, but there surely will be in the manifold. You know I'm correct but you find it galling to do anything but make unjustified remarks about my competence.

I'll leave this 'debate' now because you have chosen to complain to the moderators. I received both your complaint and their reply. You were basically slapped down and told to fight your own battles, and that they would not interfere.

I leave you victorious on your pathetic field.. This is not a debate. It is an exposition of your infantile anger an inability to be objective. Running to complain to mommy and daddy is typical of your sort. In 12 years on this board I have never complained about anything or anybody.

The moderators did not chastise me in any way. Quite the contrary. You were told what to do with your complaints in no uncertain terms.

I'll leave it at that. The floor is yours, Mr. Quizzling.

 

[cool_hardware52]

Obviosly, mixing between the two tanks takes place under the circumstances I outlined, probably primarily in the manifold. If mixing did not take place, what would be the point of having a communicating manifold?

Er ah, well the manifold exists to allow the diver access to all the gas in both tanks via a single regulator. As I have already noted this is the key advantage of manifolded tanks. The proper and intended use of the manifold has zero to do with mixing gas, none, zero. Only the ignorant would think so.

If you want to mix gas under water buy a Rebreather.

(Anybody want to give odds on how soon agilis will return with advice on rebreathers, after all he was probably in the same zipcode with one once)

Pretty sure everybody here now understands pretty clearly that you have some un met need for public humiliation. What other explanation can there be for repeatedly posting absolutely wrong information about a subject you have zero experience with or knowledge of?

First you claim both valves need to be open for filling, absolutely wrong.

Then you claim that manifolds contain some sort of magical valves that lack a mechanism to open or close, imaginative, but wrong

Then you claim gas is drawn "mostly from one cylinder, again wrong.

Now you claim manifolds exist to mix gas from one tank with the other, again wrong


Pretty sure everybody here now understands pretty clearly that you have some un met need for public humiliation. What other explanation can there be for repeatedly posting absolutely wrong information about a subject you have zero experience with or knowledge of?

It's sad really. Forums can be a place for people to learn. All you have done is spread nonsense.


Tobin

 

[Divin'Papaw]

Obviosly, mixing between the two tanks takes place under the circumstances I outlined, probably primarily in the manifold. If mixing did not take place, what would be the point of having a communicating manifold?

The issue I was addressing initially had to do with the possibility of each separate tank having a different level of O2 when using nitrox. I understand that gas from one tank will not flow into the other unless there is a difference in pressure, and that there cannot be a pressure difference if the tanks are communicating.

On the other hand, if there is a pressure difference because the valve between them is closed there will indeed be a mixing of gases when the valve is opened. This is the situation that was described by a poster who had consequently called a dive under those circumstances, and to whose post I responded. Then you decided to stick your nose in for no valid reason, apparently motivated by that inflated ego.

Obviously, if the pressures in both tanks are equal, there will be little or no mixing in either tank, but there surely will be in the manifold. You know I'm correct but you find it galling to do anything but make unjustified remarks about my competence.

I'll leave this 'debate' now because you have chosen to complain to the moderators. I received both your complaint and their reply. You were basically slapped down and told to fight your own battles, and that they would not interfere.

I leave you victorious on your pathetic field.. This is not a debate. It is an exposition of your infantile anger an inability to be objective. Running to complain to mommy and daddy is typical of your sort. In 12 years on this board I have never complained about anything or anybody.

The moderators did not chastise me in any way. Quite the contrary. You were told what to do with your complaints in no uncertain terms.

I'll leave it at that. The floor is yours, Mr. Quizzling.

I honestly think this is just a confusion in terms. Mixing and Equalizing are two very different things. The two tanks EQUALIZE via the manifold, but there is nothing then forcing the movement of air through the manifold to promote MIXING.

Say you transfill air into one side and 32% into the other with the manifold closed. If both sides were filled to the same pressure and you then opened the manifold, the two sides would hardly mix at all. A week later you'd still have close to 21% on the one side and 32% on the other. Try it sometime. You have to somehow force mixing across the manifold.

 

[decompression]

I think I can sum this up......OP, seek qualified assistance with learning to dive doubles. It's the prudent thing to do.


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[AfterDark]

I think I can sum this up......OP, seek qualified assistance with learning to dive doubles. It's the prudent thing to do.


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This is called coming full circle. Wasn't the OP asking how many SPGs were needed?

 

[agilis]

I honestly think this is just a confusion in terms. Mixing and Equalizing are two very different things. The two tanks EQUALIZE via the manifold, but there is nothing then forcing the movement of air through the manifold to promote MIXING.

Say you transfill air into one side and 32% into the other with the manifold closed. If both sides were filled to the same pressure and you then opened the manifold, the two sides would hardly mix at all. A week later you'd still have close to 21% on the one side and 32% on the other. Try it sometime. You have to somehow force mixing across the manifold.

As I wrote earlier, the stability in each tank will last only until they are used, until gas is being drawn off. Then mixing will take place, principally in the manifold if pressures in both tanks are the same, in both the manifold and the tank with lower pressure if there is a pressure differential.
Comments of mine were intentionally misquoted and distorted a few posts ago through the mechanism of turning hypothetical physics based situations into misleading and inaccurate statements of supposed fact. I will not deal with the individual who made them for reasons already given, and will disengage from this discussion as soon as possible. Some individuals seem fixated on personal attack instead of dispassionate discussion.

 

[cool_hardware52]

As I wrote earlier, the stability in each tank will last only until they are used, until gas is being drawn off. Then mixing will take place, principally in the manifold if pressures in both tanks are the same, in both the manifold and the tank with lower pressure if there is a pressure differential.
Comments of mine were intentionally misquoted and distorted a few posts ago through the mechanism of turning hypothetical physics based situations into misleading and inaccurate statements of supposed fact. I will not deal with the individual who made them for reasons already given, and will disengage from this discussion as soon as possible. Some individuals seem fixated on personal attack instead of dispassionate discussion.

When you post nonsense expect it to be quoted.

Tobin

 

[Aquavelvet]

As I wrote earlier, the stability in each tank will last only until they are used, until gas is being drawn off. Then mixing will take place, principally in the manifold if pressures in both tanks are the same, in both the manifold and the tank with lower pressure if there is a pressure differential.

This is still incorrect. You are posting out of ignorance and supposition. It would really be better if you just stopped writing as you said you would.
Just stop. You are neither making a contribution, nor listening with an intent to understand.


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[Adobo]

I agree about the isolation manifold issue; if you have a doubles set with an isolation manifold you should know that it's supposed to be open, both during filling and diving. But that point can be made in about five minutes by a half-competent LDS worker.

Storker, you gotta admit, there is more to this than a 5 minute discussion with a half-competent LDS worker. Right?

 

[agilis]

This is still incorrect. You are posting out of ignorance and supposition. It would really be better if you just stopped writing as you said you would.
Just stop. You are neither making a contribution, nor listening with an intent to understand.


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What, exactly, is incorrect? That the relative stability of different nitrox mixes in two separate but linked tanks ( as described by others) will remain only in a static situation, but not when the system is being utilized and gas drawn off as through a regulator? Is it your belief that the hypothetically different mixes in each tank will retain their distinct compositional integrity even though connected through an open manifold that is being used by a diver to draw off gas from the system? The separate gases are certainly mixing in the open manifold that is feeding the regulator. If not, Id like to know how that works, and I ask that quite sincerely. I am listening with an intent to understand.

Likewise, if two tanks attached to a closed isolation manifold have different pressures, are you asserting that the tank with the lower pressure will not receive an infusion of gas from the tank with higher pressure when the isolation valve is opened? If you believe this will not happen, please explain. If you agree with me that it must happen, will there not be a mixing of gas from each tank in the tank that had less pressure as the pressures instantly equalize?

It's not enough to say 'this is still incorrect', especially when all that may be at issue is the terminology learned by divers a trifle weak on the physics involved. That's one of the problems that sometimes arise in formal training. I saw this happen when I completed nitrox certification years ago. The instructor conceded I was correct after he researched the technical problem, but did so privately and asked me not to mention this because it would confuse the other guys who depend on literal interpretation and instructor infallibility.