Oxygen?

[gcg]

COULDNT FIGURE OUT WHERE TO PUT THIS SO I FIGURED IF YOU KNOW ABOUT THE TANKS YOU KNOW WHATS IN THEM.Sorry about the caps.......is the oxygen i weld with the same quality purity otherwise same gas as the 02 i dive with? if so i' have 2 k bottles that hold my welding oxygen its only $80 to get them both filled.. why not put my 02 in my tanks. the air is free i just pay for the 02 at the shop.i should mention i get signigigant discounts due to my assistance with the local colleges scuba class. and i fill my own tanks at the shop, so im not ignorant to the issues.

 

[kidspot]

best resource out there is the Oxy Hackers guide from http://www.airspeedpress.com - From my limited understanding of the issue, they are different "grades" but frequently come from the same source, and some divers use it... Though others would not think about it. Personally it was cheaper for me to get Aviators Breathing Oxygen than any other grade, and since it is designed for human use I don't have to worry if I need to offer it to somone else for a dive emergency.

I'm sure someone who is much more authoritative on the subject will be along shortly, but int he meantime definitely pick up the Oxygen Hackers guide...

Aloha, Tim

 

[moneysavr]

Dude,
are you asking to mix NITROX? or think Welding O-2 is Air? Welding Oxygen is pure 99.98888877665544332211 % Oxygen,
And Oxygen could & will kill you dead if used at depth's greater than 20FSW for extended limits longer than stated in O-2 training,, see course manual. air you fill your scuba tank is 21% oxygen,Nitrogen, and some trace gas.
Are you NITROX CERT?
Oh then we have to cover O-2 clean tanks,risk of fire and explosion,, but I am not even going into this!As you say you fill tanks?????!!!!!!!!!!!!!!!!!!!!!!!!!!!
Ok to cover your Oxygen questions if you were NITROX cert you would not of asked this question but here it goes,
3 -grades of O-2
Medical = is pure oxygen with not really moisture specs.you need a prescription to buy.

Aviation = is Pure oxygen with moisture specs its dry air,and is mostly used by divers and can be purchased at specialty oxygen providers for 3 times the price you pay for welding gas.

Welding Oxygen = Is pure oxygen,But this is the big but! as there is not a concern as to the container that is filled as it is not inspected each fill,could contain contaminant's,but as some will Say has to be supper pure for welding purposes.

So if you plan to mix gas take the courses and purchase the proper testing equipment,leave your mix sit over night to settle in and re test prior to dive! If you dive some one Else's mix,RE TEST IT PRIOR TO DIVE! OR YOU COULD DIE! YES DIE !
Dive safe,
Brad

 

[do it easy]

and i fill my own tanks at the shop, so im not ignorant to the issues.

I'm not clear on what you are planning on doing with this? blending nitrox, or are you trying to fill an O2 bottle for use as a deco gas?

Just so that we are on the same page, what issues would those be?

 

[gcg]

ok now that i feal like ive had my balls busted, im nitrox cert and doing advanced nitrox for accelerated deco within the month. first i never dive a mixed bottle withought analysing it, and i most certainly never trust someone elses analyzing results. im very aware that partial pressures of 02 can kill you(actually the sezures will.) second acording to the laws of physics a gases makup(percentage of 02)will not change regardless of how long it sits unless a gas with greater or less 02 is added to the bottle when mixed under pressure. im afraid that the many grades of 02 were not covered im any of my classes. my welding bottles are every bit as clean as my dive tanks as they are VIPd anually just like my dive tanks and are 02 clean just like my dive tanks. otherwise it would not be safe to put gas mixstures greater than 40% in them. i was unclear as to whether or not the 02 at the shop(dive shop) was somhow purified or cleaner than that which i obtain from my local gas supplier. although i know my welding gas is nearly 100% 02. on a side note the 02 we supply to Florida State University and what we use in our 02 kits for the diving program is the same gas we blend EAN for diving with.
please if your going to respond to this post keep the tempers down and realize im not new tot this diving thing. im a dm who works in a dive shop ocasionaly, and ive 02 cleaned many tanks and completed many gas fills for patrons, students, and instructors alike.
and i love diving with them there oxygen tanks....just kidding
again my question is in regard to the quality of the difrent oxygen sources.

 

[padiscubapro]

Medical = is pure oxygen with not really moisture specs.you need a prescription to buy.


Dive safe,
Brad

BS

Medical Oxygen is one of the lower grades of oxygen vailable, its just certified at the grade you are buying.. and in SOME juristrictions requires a prescription.

There are varying grades of medical o2.. the lowest alllows oxygen purity to be as low as 90%..

Avaiators grade is specified as 99.9%+ with a specifcic dew point (although 99%+ is not always availabel in all countries)


In several countries there is a DIVING grade, which is specified as 99.9% plus it has a very low dew point.. (very dry)

Industrial non graded is just that... This being said Industrial is usually 99% plus becaue its important to not have any contaminates when welding..

 

[do it easy]

The tanks have to be clean to handle oxygen, but the real issue is how pure the gas is. My LDS has always used Aviators grade (ABO), since it is drier (less moisture). A lot of this will be covered in a blending class.

The short answer is NO, don't use welding gas for diving.

 

[moneysavr]

Hey gcg,
Sorry!
No BB just thought that the post was a joke or some guy was going to try to take 99% o-2 and try to fill his tanks with it!
That said I know that one local blender (private) his own use, buys welding o-2 from the local air source as he dose a vis on his tanks prior to filling.
In my deco and o-2 air kit on my dive boat I use only aviation grade and its a 30 mile trip for a fill and the price nuts!
It is something with Nitrox courses they don't cover gas grades but in your-blender and O-2 provider they do,

Oh one thing you state blended gas is a stable gas after it is mixed? I am sure this was a mistake? not to start a another thread but,,
Dive safe.
Brad

 

[cyklon_300]

Dude,
are you asking to mix NITROX? or think Welding O-2 is Air? Welding Oxygen is pure 99.98888877665544332211 % Oxygen,
And Oxygen could & will kill you dead if used at depth's greater than 20FSW for extended limits longer than stated in O-2 training,, see course manual. air you fill your scuba tank is 21% oxygen,Nitrogen, and some trace gas.
Are you NITROX CERT?
Oh then we have to cover O-2 clean tanks,risk of fire and explosion,, but I am not even going into this!As you say you fill tanks?????!!!!!!!!!!!!!!!!!!!!!!!!!!!
Ok to cover your Oxygen questions if you were NITROX cert you would not of asked this question but here it goes,
3 -grades of O-2
Medical = is pure oxygen with not really moisture specs.you need a prescription to buy.

Aviation = is Pure oxygen with moisture specs its dry air,and is mostly used by divers and can be purchased at specialty oxygen providers for 3 times the price you pay for welding gas.

Welding Oxygen = Is pure oxygen,But this is the big but! as there is not a concern as to the container that is filled as it is not inspected each fill,could contain contaminant's,but as some will Say has to be supper pure for welding purposes.

So if you plan to mix gas take the courses and purchase the proper testing equipment,leave your mix sit over night to settle in and re test prior to dive! If you dive some one Else's mix,RE TEST IT PRIOR TO DIVE! OR YOU COULD DIE! YES DIE !
Dive safe,
Brad

is that someone could die laughing after reading this...

 

[DA Aquamaster]

Aviator oxygen is nice as it is quite dry and is less likely to cause problems with freeze flows in cold water.

Medical oxygen is the worst in this regard as it normally has a much higher moisture content as it is not critical and often more moisture is added at the hospital anyway to help prevent drying patients nasal and oral passages.

And I agree that in many areas welding 02 is generated in the same manner as Aviator and medical grades and is at least as pure. The difference, as stated above, is that no special protocols are required to keep it pure until it reaches the distribution point. But given the refinements in welding technology and the requirements for very pure O2, a supplier would not be in business long if they did not take great care to keep their welding O2 free of other contaminants.

But overall Aviator oxygen is the best way to go as it is assured to be safe for human use and is assured to be dry.

Mixing your own nitrox by adding 02 on top of your own O2 at the shop is a practice that works fine, but some shops will have a fit with it. One of the concerns is that if you screw up the order of opening/closing valves you could introduce higher than 21% mixes into their fill whip. In reality the amount of O2 introduced would be quite small and not noticeable or hazardous in the next AL 80 that gets filled from the whip. A more valid concern is the cleanliness of your tanks, but this is also less of an issue since the O2 is already in them and an explosion or fire would have been more likely to occur in your garage rather than their shop.

Still some shops will say absolutlely not if they find out about it. And not telling them is not really an option as the shop monkey filling the tank may then slam the air in on top of the O2 in what amounts to a very hot fill - which is a very bad idea with partial pressure blended nitrox. Plus accuracy is important and unless they are careful, your mixes are going to be off.

If you are allowed to do your own fills, the possible objections of the shop should be manageable.

As for mixes changing, the standard for partial pressure mixing is to use a very slow fill rate of no more than about 50 psi per minute. At those rates, the O2 tends to remain separated in the bottom of the tank and the air added second tends to remain on top. It can take a long time for the two to fully mix, so rolling the tank is often done to speed the process. In the extreme, I have seen a tank of 50% test at around 27% after the fill and then after rolling for a couple minutes come in within 1% of 50%.

Personally, I use a slightly higher fill rate and then put the last 200 PSI in the tank in about a minute which creates enough turbulence in the tank to fully mix the gases (at least in a 30 or 40 cu ft deco bottle). Doing this will give you accurate analyzing results immediately with no rolling require.

In my experience, if the math is right and your gauges are accurate, the mix will always be right so the first thing I do if a mix is too low is roll the tank and that normally resolves the problem.