Nitrox Tank

[idocsteve]

If I could make the Thanks button work, I'd click it...

If you're using an IBM compatible, it's the LEFT mouse button.

If it's a MAC, it's the only button.

If that doesn't work for you then you might want to get yourself checked for muscular dystrophy or some other condition that prevents you from exerting sufficient force on the mouse button.

 

[ajduplessis]

No, because scuba tanks that are contaminated and then filled with pure oxygen have been known to explode in the absence of heat/ignition.

I rest my case!!!!!

 

[PfcAJ]

no, for recreational nitrox you should not be worried about o2 cleaning tanks. They will be fine. Your lsd/dive operator will know what to do.

this is not true.



As the oxygen concentration in the fill mix increases, there is a great chance of combustion. Contaminents in the tank bind with the oxygen to make this more likely.

Off the top of my head i cant recall how they actually clean the tank but whatever they do, once the tank is certified 02 clean, it's labeled as a nitrox tank with a sticker and even if it's filled with air, the fill has to be done with filtration, so that the air is also at the same high quality of clean 02.

New tanks are already clean as far as i know.

so what you are saying is that all recreational nitrox tanks must be o2 clean?

- this means that no shop will give you a nitrox fill unless they have cleaned the tanks themselves, as they will be foolish to trust any other.
- it also means that if you don't have o2 clean regs you are also in deep pooh.
- it also means that once you have used normal air (unfiltered), all the equipment you use then is no longer o2 clean and thus not usable for nitrox.

I think the diving industy is about to "blow" up!!!

really? The dive shop won't give you a fill unless they cleaned the tank themselves even if it's got a sticker on it? According to your logic, then a shop tech won't fill a tank that has not been visually inspected or hydro'd by them because they would be foolish to trust any other. Maybe he shouldn't be intimate with his significant other unless she provides proof of a recent std panel because she could be lying. Maybe the dive shop owner won't eat food he hasn't prepared himself because who knows what could be in there? Maybe when he gets his car back from the shop he's going to put it up on a jack to make sure the work was done properly?

regs do not have to be 02 cleaned when used with recreational diving nitrox mixes. Tanks do need to be 02 clean when used with recreational diving nitrox mixes.

if you use normal unfiltered air in your tank it will be need to be cleaned again prior to be filled with nitrox (depending on whether it's banked or blended of course).

you need fuel, o2 and heat/ignition to have a fire/explosion. Do you argree?

If you fill an empty no-o2 clean tank with o2 at a very slow rate like you always should (this means no heat or ignition source), meaning you only have 2 of the 3 "items" to start/sustain a fire. Please explain how this is going to end up in a fire/explosion?

Please also explain how recreational nitrox require a o2 clean tank and valve but not the regs?

no, because scuba tanks that are contaminated and then filled with pure oxygen have been known to explode in the absence of heat/ignition. If they didn't well then there would be no point in having tanks 02 cleaned in the first place.

i rest my case!!!!!

Wat?!

The entire point of cleaning a tank is to remove hydrocarbons. The reason for this is that a nitrox tank will come into contact with 100% o2 during partial pressure blending.

Regs, OTOH, don't come into contact with 100% o2. If they do, then they need to be cleaned.

 

[idocsteve]

I rest my case!!!!!

Yes of course you do.

Now go have a cookie.

Just one!

And make sure you wash your hands first, we don't want any contaminents in there.

 

[ajduplessis]

idocsteve,

OK Einstein, I had my cookie and washed my hands. Now, please once again explain how you can have a fire with only O2, a fuel source but NO heat or ignition source?

Maybe PfcAJ can help you out.

 

[boulderjohn]

idocsteve,

OK Einstein, I had my cookie and washed my hands. Now, please once again explain how you can have a fire with only O2, a fuel source but NO heat or ignition source?

Maybe PfcAJ can help you out.

Because O2 is such an excellent oxidant that in high enough concentrations the right fuel source can ignite at ambient temperatures. It was one of the first things I learned in my blending class.

 

[Slamfire]

Not just high concentrations (fO2) but also high pressures (pO2). When you have a 100% O2 Al 40 tank at 3000 psi and you quickly open the valve to pressurize your unclean reg, you are increasing the pressure inside the regulator by more than 200 times in just a fraction of a second. That in itself can provide a good amount of heat in localized areas. Yes, enough heat to ignite silicon grease packed inside an ambient pressure chamber of a piston first stage regulator kitted for cold water diving. It has happened before and probably will happen again.

Changes in pressure also mean changes in other properties such as boiling point or autoignition temperature. The higher the pressure and the higher O2 concentration, the lower an autoignition temperature becomes.

From wikipedia (emphasis is mine):

The autoignition temperature or kindling point of a substance is the lowest temperature at which it will spontaneously ignite in a normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical will ignite decreases as the pressure increases or oxygen concentration increases.

Theoretically, ajduplessis may be right when he says no heat. No heat would mean absolute zero temperature (-273 ^oC). But I doubt that is what he meant. You lower the autoignition temp enough with high O2 concentrations and pressures, and it could very well end up lower than ambient temperature, which means it'll blow up anytime...

 

[PfcAJ]

idocsteve,

OK Einstein, I had my cookie and washed my hands. Now, please once again explain how you can have a fire with only O2, a fuel source but NO heat or ignition source?

Maybe PfcAJ can help you out.

You should probably just take a time out and listen. You're not making a good case for yourself, bud.

 

[idocsteve]

idocsteve,

OK Einstein, I had my cookie and washed my hands. Now, please once again explain how you can have a fire with only O2, a fuel source but NO heat or ignition source?

No need, that's been done by our fellow ScubaBoard posters who are much more versed in the subject than I am.

But I do appreciate the Einstein comparison, thanks.

:cool2:

 

[ajduplessis]

Not just high concentrations (fO2) but also high pressures (pO2). When you have a 100% O2 Al 40 tank at 3000 psi and you quickly open the valve to pressurize your unclean reg, you are increasing the pressure inside the regulator by more than 200 times in just a fraction of a second. That in itself can provide a good amount of heat in localized areas. Yes, enough heat to ignite silicon grease packed inside an ambient pressure chamber of a piston first stage regulator kitted for cold water diving. It has happened before and probably will happen again.

Changes in pressure also mean changes in other properties such as boiling point or autoignition temperature. The higher the pressure and the higher O2 concentration, the lower an autoignition temperature becomes.

From wikipedia (emphasis is mine):

Theoretically, ajduplessis may be right when he says no heat. No heat would mean absolute zero temperature (-273 ^oC). But I doubt that is what he meant. You lower the autoignition temp enough with high O2 concentrations and pressures, and it could very well end up lower than ambient temperature, which means it'll blow up anytime...

I appreciate your feedback. However heat/pressure is being raised time and time again. The debate is around O2 and fuel only. No heat or ignition source.