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View Full Version : New Tanks: Fill with Air or Nitrox?



ravenfish
03-11-2008, 13:23
So I just bought new AL80's. Now, do I have them prepped for Nitrox or air? I am Nitrox certified and have only used Nitrox since. However, I am not against air. Nitrox is just very common where I dive locally and on vacation. I guess the only real issue is that of cost. Is the extra cost of Nitrox fill and O2 cleaning worth it? I know a lot of shops that don't charge for regular air fills for loyal customers and service for air tanks are cheaper. Air or Nitrox?

skdvr
03-11-2008, 13:31
If it is a brand new tank it should be NITROX Reday to 40%, which means that if they are using premixed NITROX it can be filled with NITROX as long as you do not exceed 40% O2. If your shop does partial pressure fills then you will have to get it O2 cleaned before they can put NITROX in it. The cost is not that much for a O2 cleaning of the tank and valve, espically if you plan on diving NITROX a lot. If you are only going to dive NITROX every once in a while you would probably be better off just to rent a tank with NITROX in it for those specific dives.

Phil

ReefHound
03-11-2008, 13:35
Depends on your diving needs. You're just wasting money using nitrox for 30 foot pond dives but if most of your dives are in the 80 to 100 foot range then consider nitrox. You can't really mix the two since an air fill will contaminate your O2 clean tank. Some places will fill your air tank with nitrox if they are running from banks.

skdvr
03-11-2008, 13:47
You can't really mix the two since an air fill will contaminate your O2 clean tank. Some places will fill your air tank with nitrox if they are running from banks.

I thought that was only the case if the filling station did not use Grade E air? If that was the case I would not dive it any way.

Phil

No Misses
03-11-2008, 13:49
Most cylinders ship “O2 service ready”. If you specify that you want O2 service, the LDS needs to use an O2 service cleaned valve assembly and O-rings, and label the cylinder as such (O2 cleaned/ready).

The second consideration is; where are you going to get fills? You only need an O2 service cylinder if you are using PP (Partial Pressure) filling. Any time that the Cylinder will be exposed to >23.5% O2, you need to have it cleaned for O2 service. If your LDS or FSO (Fill Service Operator) uses banked EANx and/or a membrane system, your cylinders will never be exposed to >40% O2 and do not need to be O2 service ready (cleaned).

A few more points on EANx
1. The DOT (Dept of Transportation) is the governing body charged with regulation of compressed gas cylinders. They state that you must use an O2 service cleaned cylinder any time that it will be exposed to >40% O2, that it must be in current hydro, and that it have a contents label (what % mix). They do not care about VIP stickers or the big yellow and green "Nitrox" label.
2. Some LDS/FSO do not understand the Laws as written. I have dealt with operators that insisted that all Nitrox cylinders have the O2 Service tag, VIP, and big wrap around Nitrox label.
3. VIP stickers and big “Nitrox” wraps are a dive industry thing. Even though it is not a law, most FSO will not fill your cylinder without a current VIP sticker. A good number of FSO are not hung up about the “Nitrox” wrap. They understand that it is a suggestion from PADI, but you are not required to have one.

End of RANT :-)

I hope some of this information helped.

texdiveguy
03-11-2008, 13:55
Congrats on the purchase...pretty exciting is it not!!

As others have mentioned above those 'new' tanks/valves are ready from the factory for premixed nitrox up to 40%.

IF your LDS is PP filling their nitrox fills than you will need the tanks/valves O2 cleaned and thus labeled such.

Remember if you go the O2 cleaned route....the only AIR you can fill those tanks with in the future is going to be pre banked Modified Grade E air or scuba grade air run thru a 'hyper filter' prior to entering your tanks.

:)

mark44883
03-11-2008, 13:59
fill with o2

CompuDude
03-11-2008, 13:59
So I just bought new AL80's. Now, do I have them prepped for Nitrox or air? I am Nitrox certified and have only used Nitrox since. However, I am not against air. Nitrox is just very common where I dive locally and on vacation. I guess the only real issue is that of cost. Is the extra cost of Nitrox fill and O2 cleaning worth it? I know a lot of shops that don't charge for regular air fills for loyal customers and service for air tanks are cheaper. Air or Nitrox?

Depends on how the local shops fill. If they pre-mix or use membrane systems, you can switch back and forth freely and don't need to worry about it. If they're doing PP blending, then you need o2 clean tanks. At that point you need to consider if you're willing to dive ONLY Nitrox (and/or pay extra for o2-clean air fills). Otherwise, you really need more than one tank.

texdiveguy
03-11-2008, 14:03
Most cylinders ship “O2 service ready”.

IMO.... it is still best to O2 clean even factory new Al. cylinders if you intend them for O2 gas (40%+) service....it's an easy process and better ensures it truly is O2 clean....when it comes to steel cylinders going into O2 gas service, its 'always' a must to O2 clean those bad boys.

cummings66
03-11-2008, 14:05
I know in MO that the dive shop down south (SS) uses modified grade E and my true LDS also has Modified Grade E. I suspect any shop that he's sold a compressor to has it, but I don't know all of those.

I know he services the compressors for man fire departments, ambulance districts, and Scuba Shops. He strongly believes in Modified Grade E air for some reason and that's what he pushes.

I know some dive shops using Grade E and some that won't test their air for some reason.

skdvr
03-11-2008, 14:06
OK, so if I have a O2 clean tank and I am going to get a regular air fill somewhere other than my normal LDS what do I need to ask to see (Grade sheet, Label, Sticker)to make sure it will not contaminate my O2 clean tank?

I guess everytime I have had air put into my one O2 cleaned tank it has been at my LDS and it is from the same air source that they top off the tank with when it is PP filled...

Phil

cummings66
03-11-2008, 14:06
[quote=texdiveguy;143998when it comes to steel cylinders going into O2 gas service, its 'always' a must to O2 clean those bad boys.[/quote]

It seems rust commonly happens in steel tanks, perhaps from the rapid release of air when you get fills? Rust is bad for O2.

texdiveguy
03-11-2008, 14:07
At that point you need to consider if you're willing to dive ONLY Nitrox (and/or pay extra for o2-clean air fills).

I our neck of the woods shops that offer O2 clean air will charge around $2.00 a fill more to cover filter cost.....this is pretty common practice to charge a wee bit more.

skdvr
03-11-2008, 14:12
So I guess it is not Grade E I need to keep an eye out for. I need to make sure that it is Modified Grade E? Is that correct?

Phil

texdiveguy
03-11-2008, 14:15
OK, so if I have a O2 clean tank and I am going to get a regular air fill somewhere other than my normal LDS what do I need to ask to see (Grade sheet, Label, Sticker)to make sure it will not contaminate my O2 clean tank?

I guess everytime I have had air put into my one O2 cleaned tank it has been at my LDS and it is from the same air source that they top off the tank with when it is PP filled...

Phil

Most reputable shops will not fill labeled O2 clean tanks with air if their air is not O2 clean....but it is your responsability to ensure this does not happen. Sounds like your LDS is running banked air thru a hyper filter system prior to filling your O2 clean tank. A shop should never object to you asking for proof their air is O2 clean air....if they do, you should give a big 'hmmmmmm' and find another fill station.

skdvr
03-11-2008, 14:20
Most reputable shops will not fill labeled O2 clean tanks with air if their air is not O2 clean....but it is your responsability to ensure this does not happen. Sounds like your LDS is running banked air thru a hyper filter system prior to filling your O2 clean tank. A shop should never object to you asking for proof their air is O2 clean....if they do, you should give a big 'hmmmmmm' and find another fill station.


So then do I need to look for Grade E or Modified Grade E? I just want to make sure that when I go to other shops for air (Not that often) that I do not put the next person at risk that is going to PP fill my tank.

Phil

BSea
03-11-2008, 14:38
Most reputable shops will not fill labeled O2 clean tanks with air if their air is not O2 clean....but it is your responsability to ensure this does not happen. Sounds like your LDS is running banked air thru a hyper filter system prior to filling your O2 clean tank. A shop should never object to you asking for proof their air is O2 clean....if they do, you should give a big 'hmmmmmm' and find another fill station.


So then do I need to look for Grade E or Modified Grade E? I just want to make sure that when I go to other shops for air (Not that often) that I do not put the next person at risk that is going to PP fill my tank.

Phil
To be safe, I just fill my nitrox tanks with nitrox when I'm on a trip. My LDS fills all air tanks with "Clean" air. Since they do PP blending, the air they top off the nitrox tanks is the same air they fill regular tanks. So locally I use both in my nitrox tanks. Depending on your shop, you could do what I do, or just use 1 for nitrox & 1 for air. Then when you get your next tank(s) you can make them whatever works best for your type of diving.

Anybody notice that tanks are genetically related to rabbits?

ravenfish
03-11-2008, 14:41
WOW! I didn't expect so many replies in such little time. After reading through the posts I am a bit confused. Please a little tutorial on banked air and membrane fills. Cleaned O2 is air(21%) run through the same air filter system as EANx?

skdvr
03-11-2008, 14:43
Most reputable shops will not fill labeled O2 clean tanks with air if their air is not O2 clean....but it is your responsability to ensure this does not happen. Sounds like your LDS is running banked air thru a hyper filter system prior to filling your O2 clean tank. A shop should never object to you asking for proof their air is O2 clean....if they do, you should give a big 'hmmmmmm' and find another fill station.


So then do I need to look for Grade E or Modified Grade E? I just want to make sure that when I go to other shops for air (Not that often) that I do not put the next person at risk that is going to PP fill my tank.

Phil
To be safe, I just fill my nitrox tanks with nitrox when I'm on a trip. My LDS fills all air tanks with "Clean" air. Since they do PP blending, the air they top off the nitrox tanks is the same air they fill regular tanks. So locally I use both in my nitrox tanks. Depending on your shop, you could do what I do, or just use 1 for nitrox & 1 for air. Then when you get your next tank(s) you can make them whatever works best for your type of diving.

Anybody notice that tanks are genetically related to rabbits?

My LDS does the same thing. Everyone gets the same air that they use for PP fills, even if they are only getting air. I just wanted to make sure if I get them filled while I am at the lake that I can make sure that it will not negate my O2 cleaning.

Thanks to everyone for all the info.

Phil

MSilvia
03-11-2008, 14:55
After reading through the posts I am a bit confused.
I'll try to simplify it for you... anything that might come into contact with a gas that has a higher oxygen content than 40% needs to be O2 cleaned. Anything that will not, does not.

If your LDS does partial pressure fills, that basically means they mix the nitrox in your tank. Filling it part way with oxygen, and then topping it off with clean air. Since the tanks getting filled this way do get exposed to pure oxygen, they need to be oxygen compatible, and not be contaminated with "dirty" air that might have hydrocarbons and whatnot in it. (thanks to No Misses for catching my error)

If your LDS pre-mixes their nitrox, they might keep a "bank" of EAN40, which they can then use for partial pressure blending, or they might even keep banks of EAN36 and EAN32. Since a tank filled here will never be exposed directly to pure oxygen during the fill process, it doesn't matter if it's O2 clean, if it gets filled with questionably clean air, or any of that. You can put whatever breathing gas you want in it, so long as it doesn't get exposed to a gas with more than 40% oxygen.

ravenfish
03-13-2008, 11:36
I am going with Nitrox. The shop will initially O2 clean the tanks and fill with clean air. Now I can only fill the tanks with at least clean air, banked EANx or PP fill (pure O2 or >EAN40 with clean air). "Clean air" is what exactly? Grade E Oxygen Compatible Air?

skdvr
03-13-2008, 11:40
"Clean air" is what exactly? Grade E Oxygen Compatible Air?

Modified Gade E

That is what you want to look for on their air certification.

At least that is the way I understand it...

Phil

doczerothree
03-13-2008, 11:52
Enjoy your new tanks, You're going to have some good stories. I'd get them cleaned.

ravenfish
03-13-2008, 11:54
Is there is a difference between Grade E compatible and Modified Grade E?

skdvr
03-13-2008, 11:56
Is there is a difference between Grade E compatible and Modified Grade E?

The way I understand it.

Grade E is regular scuba air quality.

Modified Grade E is able to be mixed with pure O2.

Hopefully someone else will chime in and let us know if I am mistaken or not...

Phil

CompuDude
03-13-2008, 12:56
Is there is a difference between Grade E compatible and Modified Grade E?

The way I understand it.

Grade E is regular scuba air quality.

Modified Grade E is able to be mixed with pure O2.

Hopefully someone else will chime in and let us know if I am mistaken or not...

Phil

Correct.

"Hyperfiltered" air is another way that Mod Grade E air is sometimes referred to, btw. Also, "OCA" (Oxygen-compatible air).

Point being, you put regular scuba air from a regular compressor on some guy's boat or some random dive shop that does not deal with oxygen-compatible gas, you have just dirtied your tank and it is no longer o2 clean until you pay to have it cleaned again.

ravenfish
03-13-2008, 15:19
Is anyone familiar with Dutch Springs in PA? They state they fill with Grade E Oxygen Compatible Air. Does that = OCA? Is that good for an O2 cleaned tank?

CompuDude
03-13-2008, 15:51
Is anyone familiar with Dutch Springs in PA? They state they fill with Grade E Oxygen Compatible Air. Does that = OCA? Is that good for an O2 cleaned tank?

Not familiar, but you could probably call them and find out easily.

It bothers me that they use two phrases that mean two different things: OCA and Grade E. Either they don't know what they're doing, or they're being sloppy by not including the "Modified" in the "Grade E" in their description. Sloppy work by the people I'm trusting to fill my tanks with gas to keep me alive makes me nervous.

in_cavediver
03-13-2008, 20:07
A few more points on EANx
1. The DOT (Dept of Transportation) is the governing body charged with regulation of compressed gas cylinders. They state that you must use an O2 service cleaned cylinder any time that it will be exposed to >40% O2, that it must be in current hydro, and that it have a contents label (what % mix). They do not care about VIP stickers or the big yellow and green "Nitrox" label.
2. Some LDS/FSO do not understand the Laws as written. I have dealt with operators that insisted that all Nitrox cylinders have the O2 Service tag, VIP, and big wrap around Nitrox label.
3. VIP stickers and big “Nitrox” wraps are a dive industry thing. Even though it is not a law, most FSO will not fill your cylinder without a current VIP sticker. A good number of FSO are not hung up about the “Nitrox” wrap. They understand that it is a suggestion from PADI, but you are not required to have one.



Not to nitpick but the DOT isn't really concerned with dive gases etc. It was the diving industry who came up with the 40% thing. DOT goes with CGA and the CGA says anything over 23.5% must be cleaned to 02 standards and labeled as contents other than air. (Oxygen or oxygen/nitrogen blend with percentages). They also claim any time a cylinder changes from Nitrox or 02 service to air service, it must be cleaned. IE, different blends of nitrox or air to nitrox etc. Its based on percentages so Nitrox 21 doesn't count.

Generally speaking, dive uses are isolated and a very small part of the compressed gas market that those little issues just get ignored. Now, if you were to have the industrial gas supplier fill your tanks, they'd require that service be done.

anvil
03-13-2008, 20:25
Here in NZ everyone is into the membrane system, so swapping gases is no prob,Im not sure how it works tho as Im about the only wreckdiving on air still.Anyone explain?

Crimediver
03-13-2008, 21:47
Not to nitpick but the DOT isn't really concerned with dive gases etc. It was the diving industry who came up with the 40% thing. DOT goes with CGA and the CGA says anything over 23.5% must be cleaned to 02 standards and labeled as contents other than air. (Oxygen or oxygen/nitrogen blend with percentages). .[/quote]

That is why I generally stick to 21 % Nitrox.

CompuDude
03-13-2008, 22:32
Here in NZ everyone is into the membrane system, so swapping gases is no prob,Im not sure how it works tho as Im about the only wreckdiving on air still.Anyone explain?

Air goes up to membrane. Membrane filters out some of the Nitrogen.

Stuff that makes it to the other side of the membrane has more Oxygen.

In a nutshell.

cummings66
03-14-2008, 07:06
Simple but accurate explanation. I wish more shops had them around here as it would make O2 cleaning a non issue.

No Misses
03-14-2008, 09:28
Here is the test results from my LDS (Fill Express). They test there "Air" to this standard - CGA G-7.1-2004 Grade E (Modified Grade E). You should ask to see the test reults for your LDS/FSO.

If you want to see thier current results look here http://fillexpress.com/library/testresults.pdf

texdiveguy
03-14-2008, 09:49
Here is the test results from my LDS (Fill Express). They test there "Air" to this standard - CGA G-7.1-2004 Grade E (Modified Grade E). You should ask to see the test reults for your LDS/FSO.

If you want to see thier current results look here http://fillexpress.com/library/testresults.pdf

Most quality fill stations will post this cert. in plain view for all to examine.

in_cavediver
03-14-2008, 16:09
Here is the test results from my LDS (Fill Express). They test there "Air" to this standard - CGA G-7.1-2004 Grade E (Modified Grade E). You should ask to see the test reults for your LDS/FSO.

If you want to see thier current results look here http://fillexpress.com/library/testresults.pdf

yea but since fill express is your gas supplier - why dive air? They charge the same for air as nitrox......

Duckydiver
03-14-2008, 20:43
I just bought a Nitrox tank yesterday and the price between a o2 clean tank and normal tank was the slightly more expensive valve and the cost of the nitrox sticker. In total, it was minimal. On the other hand, to get an older tank o2 cleaned, that was a bit of money.

ravenfish
03-16-2008, 13:56
To be safe, at anytime I feel that the nitrox fill in my O2 cleaned tank is not "clean" I should not have it PP filled until I have it O2 cleaned again. But until then I may fill with banked EANx under 40%, clean air or Modified Grade E.