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gxsr_sarge
March 2nd, 2009, 03:28 PM
Greetings all: I checked and it seems as though this topic hasn't been covered in this sub-forum since mid-2007 (http://www.scubaboard.com/forums/compressors-boosters-nitrox-trimix-blending-systems/194802-welding-versus-medical-o2.html) so I figured I could revive the topic.

I'm in the final stages of setting up my new home PP blending system and am now trying to secure O2 and He. I thought that I had secured "Tech Diving Grade" O2 w/ Praxair after having sent in my application showing my c-cards for both blending EAN and Trimix gases and also for using them. They just gave me the Heisman and told me that since I wasn't a "certified retail dive center" (whatever that means), I couldn't buy from them :no:. So I'm looking at industrial/welding or "aviator" grade O2.

I don't think I'll have a hard time buying welding O2. I just called Praxair's "front desk" and asked them what buying O2 entailed. They immediately asked "what for" - I said, "Oh, for oxyacetylene welding". The guy immediately said to just swing by, lease a tank and you're set.

I've asked a few suppliers before about Medical O2 and they said no-way b/c you need a prescription. So that leaves Aviators as far as the other "breathable gas".

My questions (please consider any or all) are as follows:

- What response would I give for the inevitable "why do you need aviator's grade O2 for"?
- Is there a valid "welding or torch cutting" reason to ask for a purer, dryer or cleaner form of O2?
- What are your experiences in dealing w/ suppliers in buying O2 or He? Do you tell them what it's for?
- Lastly, HAS ANYONE EVER HEARD OF ANYONE BEING HARMED FROM BREATHING "WELDING" GRADE O2? I know that many may prefer to buy Medical or Aviators just to feel cozy - but really, does it matter?

Cheers

steamtrollnuke
March 2nd, 2009, 04:16 PM
From what I remember from the Navy Nuclear Emergency welder class I took,
Technical 02 (welding) is at least 99.8% pure. solid green bottle
Medical 02 is at least 99.9% pure, white top half
Aviator 02 is at least 99.9% pure and actually has a lower moisture content than Medical 02, white band

We used Aviator grade 02 for the entire welding class, I don't see why you should have to give a reason why you want aviator grade 02.

gxsr_sarge
March 2nd, 2009, 04:51 PM
Does "purer" = "more breathable"?

For example, Matheson Tri-Gas categorizes their O2 as follows:

Research Purity, 99.998% (< 5ppm Argon, 0.1ppm CO2, 0.1 CO)
Matheson Purity, 99.997% (< 15ppm Argon, 1ppm CO2, 1ppm CO)
Ultra High Purity, 99.98% (< 1ppm CO2, 1ppm CO - no argon listed)
Zero Gas, 99.8% (doesn't list tolerances)
Extra Dry, 99.6% (doesn't list tolerances)

They all indicate "not for human consumption". I couldn't find anything that listed "aviator".

I'm guessing that Research Purity is best though they don't offer 337 Cubic Ft sized cylinders. The middle three above are the only ones that come in 337's (1L's).

pescador775
March 2nd, 2009, 05:46 PM
I see no need to revisit this topic or define "pure" beyond what is obvious lest it become an Abbot and Costello act, "Who's on First?" Here is some reading material. BTW, I use welding oxygen.

Applications Detail (http://www.mhoxygen.com/index.phtml?nav_id=25&article_id=18)

gxsr_sarge
March 2nd, 2009, 06:04 PM
I see no need to revisit this topic or define "pure" beyond what is obvious lest it become an Abbot and Costello act, "Who's on First?" Here is some reading material. BTW, I use welding oxygen.

Applications Detail (http://www.mhoxygen.com/index.phtml?nav_id=25&article_id=18)

pescador775, I don't mind (and welcome) the Abbot & Costello act. I'm here to acquire knowledge from folks like you on how and where they buy gases (along with the "tactics" ;)). Something could have changed since 2007 - I don't know. I suppose that with over 2600 posts, you've seen it all but I'm still a relative "newbie" both to the forum and the blending. So please .....

pescador775
March 2nd, 2009, 06:22 PM
There is no change. Local gas suppiers are independant actors. Individually, they set rules, sell to whom and at what price they choose. They appear to hold to the view that they are "pros" and everybody else is a sucker or a potential hazard or lawsuit waiting to happen. They misinterpret rules for perscription drugs and other things or make up their own. Buy some aviator's oxygen and tell them it is for industrial use. However, any differences with welders oxygen might be hard to prove. Any inert gas such as nitrogen or argon is a potential contaminant but the kick back would be from welders as opposed to divers. Before filling, the supplier is supposed to draw a vacuum on the tank before transfilling pure, cryo oxygen. The are probably conscientious about this because if a flammable substance were present in the tank they would be first to hear about it (booooom)..

Thalassamania
March 2nd, 2009, 06:30 PM
It is my understanding that the only actual difference between welding oxygen and medical oxygen is that at the final delivery point the suck a vacuum on the bottle before filling it with medical oxygen. Same product, same cooling tower ... different delivery protocol.

cool_hardware52
March 2nd, 2009, 06:43 PM
It is my understanding that the only actual difference between welding oxygen and medical oxygen is that at the final delivery point the suck a vacuum on the bottle before filling it with medical oxygen. Same product, same cooling tower ... different delivery protocol.

Would you introduce High pressure Pure O2 into any commercial cylinder of of unknown provenance, particularly if this cylinder is at or near empty?

I wouldn't and my local gas supplier won't either.

Tobin

Thalassamania
March 2nd, 2009, 07:14 PM
I would not, but evidently it is done with welding oxygen cylinders thousands of times every day.

Gilldiver
March 2nd, 2009, 09:52 PM
Having been at all of the major gas manufacturers and re-packagers for a major aerospace corp doing a corporate purchasing agreement, I found that there is no, that means zero, difference between how tanks are handled until you get above UHP levels. That means 5.0 grade or 99.9990%.

All the pure gas comes from a liquid source, welding tanks, etc get vacuumed and refilled in batches of up to 12. Once the batch is filled in about 5 minutes, the operator checks his computer screen and the screen tells him what is need at that instance. If anything other then welding gas is required, a bottle from the batch of 12 is tested and the stickers are printed out and the bar codes on the tank are recorded. So from that batch of 12 tanks, 6 may be welding, 2 Aviators, and the rest UHP.

Aluminum medical tanks are treated slightly different if they are aluminum or smaller then the 200 or 300 cubic foot tanks.

So, the difference between welding O2 and He and UHP O2 and He is a piece of paper, nothing more. But if you sell that gas or give it to anyone else, that piece of paper can be very valuable if you get sued.

Now when you get above 5.0 (99.9990%) the bottles are treated differently. They will be heated to above 212F to dry out any water, flushed and vacuumed at least twice, filled and may be individually tested and cost a lot more then any diver will ever want to pay.

Last, the major gas plants are set up to fill over 10,000 bottles per year. Just how much care do you think they can give to each one? Also, the fill stations are all on what looks a lot like a unheated loading dock.

rjack321
March 2nd, 2009, 09:58 PM
Sarge,
Welding O2 hasn't changed since 2007. And there are no reported illnesses or deaths because of it. As you found out the gas companies will make up rules just to be pinheads. The big chains like praxair and sometimes the smaller vendors as well.

Do this:
Get oxyhacker's handbook.
Read it.
Go in and buy O2, welding is fine but aviators avoids the miniscule risk of something like acetylene being in the tank (which you can easily smell).
Do not give them any more information than necessary to avoid creation of more made up rules.
Although O2 has a special valve fitting (unlike He) Analyze your gas every time
Once you have been a customer for awhile and proven that you are not an idiot by bringing their tanks back etc you may want to discuss what you are doing with the gas. Until then do not volunteer information. You are an individual working in your garage. More than that is none of their business.

gxsr_sarge
March 2nd, 2009, 10:08 PM
Gilldiver and pescador775, I appreciate your detailed responses.

PS: Pesky, in addition, thanks for the handy transfill/tank equalization formula that I found in an old thread. http://www.scubaboard.com/forums/2624137-post29.html

gxsr_sarge
March 2nd, 2009, 10:21 PM
Sarge,
Do this:
Get oxyhacker's handbook.
Read it.
Go in and buy O2, welding is fine but aviators avoids the miniscule risk of something like acetylene being in the tank (which you can easily smell).
Do not give them any more information than necessary to avoid creation of more made up rules.
Although O2 has a special valve fitting (unlike He) Analyze your gas every time
Once you have been a customer for awhile and proven that you are not an idiot by bringing their tanks back etc you may want to discuss what you are doing with the gas. Until then do not volunteer information. You are an individual working in your garage. More than that is none of their business.

Great advice. In fact, I've downloaded and will read a bunch of articles on oxyacetylene welding to get my "lingo" up on the subject in case I get "quizzed". I've used an arc-welder but never this stuff. I just think they don't want to hear that it's for "human consumption".

dannobee
March 2nd, 2009, 11:14 PM
A couple of tips. See if you can purchase tank(s) instead of leasing. That will save money if the tanks are just sitting.

Tell them you're using it for some metal art projects if they ask. Those typically use a lot of oxygen and not so much acetylene.

When you start to need helium, tell them you've stepped up and bought a heliarc welding machine and your regulator is "set up" for helium. Tell them you'd like to know the difference between helium and "gold gas" for TIG/MIG welding.

Don't offer any more info than that.

It all comes from the same cryogenic tank anyway (fractional distillation process).

You'll be bringing back the tanks with more oxygen than I care to, so keep an eye out for a decent used compressor, then use a nitrox stick.

You're starting down a slippery slope and will soon have more tanks and mixing stuff than your local dive shop.

Good luck!

rigdiver
March 3rd, 2009, 12:58 AM
Isn't there a law in Florida where any diver can legally buy Oxygen?
I talked with Praxair @ DEMA and was told they would sell gas if you are a certified blender and show them that you keep records/logs. Praxair has a "Diver Grade" Oxygen.

gxsr_sarge
March 3rd, 2009, 11:40 AM
Isn't there a law in Florida where any diver can legally buy Oxygen?
I talked with Praxair @ DEMA and was told they would sell gas if you are a certified blender and show them that you keep records/logs. Praxair has a "Diver Grade" Oxygen.

In fact, yesterday I gave Praxair a little pushback on their decision asking them to identify a "suit" at corporate that could give me a good reason NOT to sell gas to a certified blender/user. (I couldn't help it, I'm a lawyer).

I think may have changed their minds as I got a price quote this AM for O2 and He along with a message that my account is being set up....

Nonetheless, based on all of the responses thus far, my comfort level with welding O2 is as equally as "pure" - 99.95%.

Thanks.

Peter_C
March 3rd, 2009, 02:46 PM
I use welding grade from Praxair. Somehow Dannobee gets gas cheaper than I do and I have a commercial account at Praxair with the same discount as a welding shop. I purchased one of my welders and my plasma cutter at Praxair for less then I could find them anywhere else including online.

One of the best ones I have heard for aviator grade is to tell them you are building a space capsule :rofl3:

cool_hardware52
March 3rd, 2009, 03:37 PM
One of the best ones I have heard for aviator grade is to tell them you are building a space capsule :rofl3:

I have to imagine that some people would have no trouble convincing the average welding supply sales clerk that they are in desperate need of a space capsule of their very own.


Tobin

Peter_C
March 3rd, 2009, 04:20 PM
I have to imagine that some people would have no trouble convincing the average welding supply sales clerk that they are in desperate need of a space capsule of their very own.


Tobin

Yeah, but who are they to judge stupid? They sold someone enough helium to fill balloons and go for a ride in a lawn chair :D The crazier the notion the more likely they will believe it.

Thalassamania
March 3rd, 2009, 04:45 PM
Interesting how they'll sell you breathing media for space travel, or for the life support system in a deep submersible (I've bought for that, not a problem) but not for a little underwater EVA.

rigdiver
March 3rd, 2009, 08:26 PM
This thread brings back some old and not so fond memories. I initially started trying to buy Medical Grade Oxygen for partial pressure blending about 12 years ago. Air Liquide would not sell it to me without a "prescription." Being an R.N. and EMT-Paramedic getting said prescription was easy. When I presented the prescrition to Air Liquide they then said "we are not pharmacists."
This was at the plant where air was actually cooled enough to get liquid Oxygen and Nitrogen. Thousands of cylinders were filled there everyday. Same manifold for every grade.

waterpirate
March 7th, 2009, 02:44 PM
I just called my gas supplier (Roberts Oxygen) two weeks ago to gat a lease on two bottles of therapy grade 02. The sales guy asked me for what? I responded do I have to tell you? He said yes. I told him to blend scuba gas. He replied great!!, can I interest you in a lease on the biggest cascade that you can afford?
Maybe the economy is motivating them to sell, not be dicks.
obtw that line about building a space capsule was priceless!
Eric

Norseman1
March 10th, 2009, 05:35 PM
It is my understanding that the only actual difference between welding oxygen and medical oxygen is that at the final delivery point the suck a vacuum on the bottle before filling it with medical oxygen. Same product, same cooling tower ... different delivery protocol.


FWIW, I am a Nitrox (<or= 40% O2) and Advanced Gas (>40% O2 and Trimix) Blending Instructor Trainer with TDI and hold the equivalent ratings at the instructor level with IANTD.

What I have always found to be the case with the vendors I have worked with is that Medical O2 cylinders are triple evacuated before filling and Industrial (welding) O2 cylinders are evacuated only once. Other than that they are the same gas as far as purity goes. Aviation O2 has a lower moisture content to prevent freezing in the delivery system at high altitudes. All O2 cylinders require the same level of cleanliness for obvious reasons.

Of course other vendors could have different methods and/or protocol for how they fill cylinders.

HTH

Thalassamania
March 10th, 2009, 05:40 PM
Usually I just ordered and the tanks arrived on the loading dock, we only bought medical grade for the ship, regardless of their intended purpose, so that in a diving emergency unused bottles were always available. My only direct experience with a vender's protocols is a surgical supply house, they evacuated the bottles and filled, and said that welding supply companies did not do that. Thanks for the information.

captain
March 10th, 2009, 06:10 PM
FWIW, I am a Nitrox (<or= 40% O2) and Advanced Gas (>40% O2 and Trimix) Blending Instructor Trainer with TDI and hold the equivalent ratings at the instructor level with IANTD.

Aviation O2 has a lower moisture content to prevent freezing in the delivery system at high altitudes. All O2 cylinders require the same level of cleanliness for obvious reasons.

TH

By the very nature of the process that produces oxygen the possibility of moisture in it is virtually impossible. Oxygen and most other atmospheric gases, nithogen and argon are produced in a cryogenic process that liquifies air to about -298 F.

All water vapor, carbon dioxide and carbon monoxide must be and are removed in molecular seive towers before the liquification temperature other wise the water and co2 would freeze and plug up the processing equipment. There is zero moisture in liquid oxygen so I cannot see how they can make the statement that aviators oxygen has less moisture.

The liquid oxygen is pumped at high pressure through an evaporator that turns it back into a gas and then to the cylinder filling rack.

Although there are other processes that can produce oxygen, liguification and fractional distillation is the only way to produce it at industrial volumn and economy. It is the process use by all the industral gas producers, Praxair, Air Liquide, Air Products, etc

I worked almost 30 years operating an air seperation plant for Praxair making 150 tons of oxygen a day. The unit would automaticly shutdown if moisture or co2 was detected downstram of the seive towers.

oxyhacker
March 10th, 2009, 08:21 PM
The lab guys at my gas supplier's plant told me that virtually all the O2 they sell meets aviation standards for dryness, except that every once in a while they get a tankfull that doesn't, and it always turns out to be one that was just hydroed.


By the very nature of the process that produces oxygen the possibility of moisture in it is virtually impossible. Oxygen and most other atmospheric gases, nithogen and argon are produced in a cryogenic process that liquifies air to about -298 F.

Betail
March 10th, 2009, 08:36 PM
I use the avatiation grade. They would not sell me medical grade and I figured my life was worth a few extra bucks a tank over welding gas.

Isn't there a paper trail on the cylinders used for medical and aviation that is not present for welding gas?

captain
March 10th, 2009, 09:38 PM
The lab guys at my gas supplier's plant told me that virtually all the O2 they sell meets aviation standards for dryness, except that every once in a while they get a tankfull that doesn't, and it always turns out to be one that was just hydroed.

What type of tankful. Do they mean a tank truck of liquid o2 or an individual HP cylinder or bank of cylinders that they decant from.

Point being there is no difference in the way welding, aviation and medical o2 is manufactured. Any contaminants would have to come after the manufacturing process not during. Our specifications were zero h2o, 99.98% pure o2, the .02 percent was rare earth gases such as neon, xenon, argon, kypton, etc with argon being the greatest part of the .02%

b1gcountry
March 10th, 2009, 09:49 PM
In fact, yesterday I gave Praxair a little pushback on their decision asking them to identify a "suit" at corporate that could give me a good reason NOT to sell gas to a certified blender/user. (I couldn't help it, I'm a lawyer).

I think may have changed their minds as I got a price quote this AM for O2 and He along with a message that my account is being set up....

Nonetheless, based on all of the responses thus far, my comfort level with welding O2 is as equally as "pure" - 99.95%.

Thanks.

I'm just curious, what price did you get?

oxyhacker
March 11th, 2009, 06:32 PM
Individual cylinder, like a K. Point being the the O2 is plenty dry as it comes out of the plant. Like you said.


What type of tankful. Do they mean a tank truck of liquid o2 or an individual HP cylinder or bank of cylinders that they decant from.

SCUBA_Phil
April 11th, 2009, 02:00 PM
I'm another one using welding grade O2 on my RB. Never had a problem. I have oxyhacker's book - very good. And remember, if you ever need to weld, you can do that too!

wedivebc
April 11th, 2009, 02:44 PM
If we are talking about diving applications this whole argument is really silly when you consider the purity of the crap we call air.
http://www.airchecklab.com/assets/docs/08AirSpecs.pdf

gxsr_sarge
April 11th, 2009, 11:19 PM
If we are talking about diving applications this whole argument is really silly when you consider the purity of the crap we call air.
http://www.airchecklab.com/assets/docs/08AirSpecs.pdf

Agreed!

ComputerJoe
April 22nd, 2009, 08:50 AM
I have heard much the same except that welding oxygen tanks are not drained before filling. Myself, I have bought my own cascade cylinders, cleaned them, and use them for nothing but o2. This is to avoid ANY chance of cross contamination of acetelene at a welding shop. This could happen if the oxygen tank is bled dry and the welder is using a fine brazing tip. Heck, since I partial pressure blend, I never run my tanks down lower than a couple of hundred PSI so air can not contaminate the tank.

Rick Inman
April 22nd, 2009, 09:16 AM
I'm just curious, what price did you get?

That's the funny part, too. Price seem to be something that is flexible, if you know what to say to whom.

I just picked up two of the T bottles (332cf, I think) of aviator grade. They bill me on account, but I always ask the price before I leave with the bottles. The guy said, "$32.00?" as if it was a question. I said, "No, that sounds high." So he said, "23.00?" I said, "Sure, that sounds right."

I don't know how much less the welding grade is, but $23.00 for 330cf of O2 is good enough for me.

Oh, and my supplier said that the only difference between Medical and any other grade is what they have to guarantee, not what's in the bottle. Same gas, different guarantee.

They also fill those bottles hot, in about 30 seconds, and overfill them.

BTW, with these guys, attitude is everything. If you talk the language with confidence, they will usually set you up with whatever gas you want, no questions. If they do question you, flash a nitrox card at them as if that answers everything and they will pretend they know what they are looking at, and sell you the gas. Setting up an account with them also ends all questions. All the account is, is some clerk checking your credit to see if you are billable. But once the the guy behind the counter sees you have an account, they sell you whatever you want. However, these are gas people, so YMMV, and it can change day to day and at different locations.

WD8CDH
July 28th, 2009, 09:53 AM
I have never had problems getting my cascade bottles filled but an individual rebreather bottle is almost an impossability. The medical supply places won't fill customer owned tanks even with a perscription. The welding place won't fill anything with a SCUBA valve on it.

What is a good way to get individual bottles filled? I have thought of painting them all green and using CGA540 valves and saying it for welding.

dannobee
July 28th, 2009, 11:21 AM
I have never had problems getting my cascade bottles filled but an individual rebreather bottle is almost an impossability. The medical supply places won't fill customer owned tanks even with a perscription. The welding place won't fill anything with a SCUBA valve on it.

What is a good way to get individual bottles filled? I have thought of painting them all green and using CGA540 valves and saying it for welding.

Transfill from a small ("125") welding oxygen bottle. If you're so inclined, there are small oxygen boosters available for around $2K (new) that will allow you to use up most of the source gas.

rjack321
July 28th, 2009, 05:58 PM
Transfill from a small ("125") welding oxygen bottle. If you're so inclined, there are small oxygen boosters available for around $2K (new) that will allow you to use up most of the source gas.

Yeah I swapped my 2x 250cf "K" bottles for 4x 125cf bottles. With more bottles I can always have a full one on hand. Once its only partly full e.g. <~1200psi its not much use to me for transfilling O2 anymore (although still good for PP blending 50%). So I use that last 1/2 of a cylinder to continuous blend 32%. With the 250cf bottles I needed to use ALOT of 32% before exchanging the supply cylinder. With the smaller 125cf supply bottles I can use up the dregs easier and swap for a full one sooner.

oxyhacker
July 28th, 2009, 07:39 PM
Why guess or go by hearsay or third hand gossip? Call the lab at your gas suppliers bottling plant, and ask them what the difference is between med and welding. Ask them if they vacuum welding bottles. Don't give your real name, and don't admit you are diving with the stuff.

Oh, and ask them if some acetylene backflowed into an empty O2 tank, and someone filled 1800 psi of O2 on top of it, what would happen.


I have heard much the same except that welding oxygen tanks are not drained before filling.

Killer&Griller
July 28th, 2009, 11:48 PM
Call the lab at your gas suppliers bottling plant, and ask them what the difference is between med and welding. Ask them if they vacuum welding bottles.

I did ask about the av vs weld in the beginning. I was told the biggest thing was extra drying process. As far as med vs av in layman's terms, paperwork and politics.

Oxy-- I keep meaning to order your book....... :confused:

I would like to see a thread just posting what guys are paying for 02 fills........ maybe there already is one, I didn't see it. Hummmm......... I have an idea....

WD8CDH
August 3rd, 2009, 12:35 PM
Transfill from a small ("125") welding oxygen bottle. If you're so inclined, there are small oxygen boosters available for around $2K (new) that will allow you to use up most of the source gas.

My cascade already is a bank of 4 "125" bottles. I need to find the most hassle free way to get individual RB bottles filled when I can't fill them myself.

dannobee
August 3rd, 2009, 03:28 PM
My cascade already is a bank of 4 "125" bottles. I need to find the most hassle free way to get individual RB bottles filled when I can't fill them myself.

Will the local dive shop fill up an HP tank with oxygen? At least that way you'd start out with ~3500 psi and could transfill off of it.

cool_hardware52
August 3rd, 2009, 03:43 PM
Will the local dive shop fill up an HP tank with oxygen? At least that way you'd start out with ~3500 psi and could transfill off of it.

Based on my experience I'd be stunned if a local commercial gas supplier would touch a Scuba bottle with a ten foot pole.

Tobin

dannobee
August 3rd, 2009, 06:08 PM
Based on my experience I'd be stunned if a local commercial gas supplier would touch a Scuba bottle with a ten foot pole.

Tobin

That's why I asked if the local dive shop would fill it with O2 to 3500. ;)

cool_hardware52
August 3rd, 2009, 06:23 PM
That's why I asked if the local dive shop would fill it with O2 to 3500. ;)

Oops! Gotta improve the reading comprehension:shocked2:

I'd still be pretty surprised if many (any?) LDS would be willing to pump O2 up to 3500.

Few LDS's have O2 boosters, and most are not real excited about filling beyond 3k.

Tobin

WD8CDH
August 4th, 2009, 04:59 PM
Transfill from a small ("125") welding oxygen bottle. If you're so inclined, there are small oxygen boosters available for around $2K (new) that will allow you to use up most of the source gas.


Will the local dive shop fill up an HP tank with oxygen? At least that way you'd start out with ~3500 psi and could transfill off of it.
Sure, if I had proper training as a sport rebreather diver which they want to charge me many $$$$ for. But I was trained as a commercial rebreather diver before the shop owner was even born.:shakehead:

paddler3d
August 4th, 2009, 05:29 PM
You're starting down a slippery slope and will soon have more tanks and mixing stuff than your local dive shop.

Good luck!

:rofl3:

Isn't that anything with SCUBA in it?

dannobee
August 4th, 2009, 06:08 PM
Sure, if I had proper training as a sport rebreather diver which they want to charge me many $$$$ for. But I was trained as a commercial rebreather diver before the shop owner was even born.:shakehead:

No, what I'm asking is if you're adv nitrox trained, or have DAN O2 certification, dive shops will fill oxygen tanks for you. Then if you have an HP tank (~3500 psi), and if they aren't scared and have a booster, will they fill it to the rated pressure? DAN O2 cert would be the cheap way to go if you just need the cert to obtain O2.

If you have access to a booster that is O2 cleaned, that would be another option.

Belmont
August 4th, 2009, 10:43 PM
What about Helium??

I heard there is a balloon filling grade with some air in it.

Do they have welders grade and better?

Scott L
August 4th, 2009, 10:54 PM
You guys are nuts using industrial/welders O2 or balloon grade HE. Work a few hours longer to afford the proper grade and live a full life...

Thalassamania
August 4th, 2009, 11:00 PM
You guys are nuts using industrial/welders O2 or balloon grade HE. Work a few hours longer to afford the proper grade and live a full life...While it's not the case for He, all O2 grades come off the same cooling tower. It's only a question of how the flask that you bring in for filling is handled.

Scott L
August 4th, 2009, 11:13 PM
While it's not the case for He, all O2 grades come off the same cooling tower. It's only a question of how the flask that you bring in for filling is handled.

My tech instructor scared the bejeebers out of me telling me otherwise. but I will defer to your knowledge as you have not steered me wrong yet...

Thalassamania
August 5th, 2009, 12:21 AM
Things could be different in different times and places. Ask your supplier. I think that what you'll find is that the only difference is pulling a vacuum on the flask before filling. Let me know if they tell you different, please.

oxyhacker
August 5th, 2009, 11:07 AM
If you have some secret info we don't have concerning fatalities caused by the use of welding O2, by all means let us know. But if you look at the specs welding O2 is actually purer and cleaner than med, the only difference if any being in vacuuming the tanks, and that varies with the supplier, hence the recommendation to call the plant or lab.

Since helium is used mostly for precision welding and analytical work, all the grades are pretty clean, but if you want to be extra safe, just buy one of the better ones.

Balloon grade? It's not really, technically speaking, a grade, but rather an ungraded or sub-grade, and can indeed conceal all sorts of vices. But you got to be pretty clueless to use it diving. USP medical helium, for that matter, is only two nines (99.0%) according to the specs, while the cheapest welding/industrial grade you'll usually run across is 99.5% to 99.95%.




You guys are nuts using industrial/welders O2 or balloon grade HE. Work a few hours longer to afford the proper grade and live a full life...

Cave Bum
August 5th, 2009, 11:24 AM
But if you look at the specs welding O2 is actually purer and cleaner than med, the only difference if any being in vacuuming the tanks, and that varies with the supplier, hence the recommendation to call the plant or lab.

One of the things I like to point out to folks is that most of the oxygen we buy is generated from cryogenic liquid oxygen. No matter the grade, it all comes out of the same cryogenic tank and through the same lines. This means it’s being generated from liquid at a temperature of -297.3F (-183.0C). Since water freezes at 32F (0C) the only H2O contamination we can get in generated O2 has to be added after the generation process. This also applies to just about all other types of contamination as well. The ‘grade’ specs deal more with how clean the containers you are filling are kept then with the purity of the gas that's being put into them.

WD8CDH
August 7th, 2009, 08:17 PM
No, what I'm asking is if you're adv nitrox trained, or have DAN O2 certification, dive shops will fill oxygen tanks for you. Then if you have an HP tank (~3500 psi), and if they aren't scared and have a booster, will they fill it to the rated pressure? DAN O2 cert would be the cheap way to go if you just need the cert to obtain O2.

If you have access to a booster that is O2 cleaned, that would be another option.
Like I said, I have no problem filling at home. I can fill to 3500 easily there. The problem has getting small cylinders filled in the field.

No, I don't have a DAN O2 cert. I was trained and had 10 years and over 1000 hours of rebreather, heliox, and tri-mix experience before DAN even existed. I did get recreational OW and AOW back in the early '70s (by assisting instructors so it was free;) ). The DAN O2 cert sounds like a good affordable solution, I hadn't thought of that. I really don't want to sit thru NITROX and Advanced NITROX just to do what I have been doing for almost 40 years.

WD8CDH
August 9th, 2009, 11:58 AM
Well, I think I found the solution to getting small individual RB bottles filled at an unknown welding gas supplier. I machined a CGA540 nipple(chrome, hand-tight, of course) to fit my Poseidon O2 regulator inlet. I then put a compact Sherwood chrome CGA540 valve on a D size med oxygen bottle. I then took it to a welding shop that didn't know me and told them it was for a portable welder for my 4x4. After they filled it, they reminded me keep grease from the truck off of the valve and gave me a valve protector with their name and phone number on it.:D

Other than needing an adapter to fill the O2 bottle at a diveshop, I don't see any downside to using the CGA540 fitting on the RB.

Thalassamania
August 9th, 2009, 02:54 PM
Sweet.

WD8CDH
October 8th, 2009, 04:26 PM
Just an update. I have been to 4 different welding gas suppliers with my "portable welder O2 tank" and had no problems getting it filled at any of them. Two required leaving it overnight because they only fill twenty O2 bottles at a time. They usually charge me the same as a 20CF tank even though it only holds 15CF. I know at least one of the shops filled it with the medical tank batch. Several of the counter men drove 4x4s and said they wanted to make up a tank like it for their trucks.

Tigerman
October 8th, 2009, 06:40 PM
"make up" being pretty accurate in your case? :p

5513
December 22nd, 2009, 02:36 AM
I just called my gas supplier (Roberts Oxygen) two weeks ago to gat a lease on two bottles of therapy grade 02. The sales guy asked me for what? I responded do I have to tell you? He said yes. I told him to blend scuba gas. He replied great!!, can I interest you in a lease on the biggest cascade that you can afford?
Maybe the economy is motivating them to sell, not be dicks.
obtw that line about building a space capsule was priceless!
Eric

Re: space capsule, we can tell them the He is for making it light enough to get into space so we avoid the propulsion system maybe we can get both He and O2 without a hassle.

Water Monkey
December 31st, 2009, 11:52 PM
Thanks, I learned something new today. I have been using welding gas for several years for mixing Nitrox. I was told by my supplier that it is basically the same as medical grade and that it should not be a problem so I have been using it, but I feel a little better about it after reading your post.

Water Monkey
December 31st, 2009, 11:54 PM
Thanks Gilldiver, I learned something new today. I have been using welding gas for several years for mixing Nitrox. I was told by my supplier that it is basically the same as medical grade and that it should not be a problem so I have been using it, but I feel a little better about it after reading your post.

Gilldiver
January 1st, 2010, 09:55 AM
Just remember:
1) If you sell or trade the gas that you mix
2) Use any gas that does not have a quality reconized as being appropriate by the industry, even if the only dif is a piece of paper
and
3) There is a problem with the dive, any problem

Then

You will be TOAST in a court of law.

Personal use is diffrent.

Water Monkey
January 2nd, 2010, 12:45 PM
I think another thing to remember is that your gas is only as clean as your last air fill. If your mixing your own gas and do diligent testing you can be fairly certain your getting a clean mix. But you can easly blow a seal in a filter and then all bets are off.

And I’m pretty certain the air coming out of my filtration system is no where near as clean as welding o2.

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