NITROX marked tanks MUST be filled to 24% or greater?

[NAM001]

Above 40% OR partial pressure filling requires 02 cleaning. My shop has no problem with me switching back and forth between nitrox and air in the same tank. They bank their 30% nitrox, so partial pressure filling doesn't come into play.

"Gas mixes with more than 40% oxygen require equipment, including cylinder, that has been cleaned to oxygen service specifications. Because the cylinder valve and interior will be in contact with pure oxygen, if partial pressure blending with oxygen will be used, the cylinder must meet oxygen service standards, even if the final enriched air blend will have less than 40% oxygen. The standard SCUBA cylinder doesn't meet these requirements." ~PADI

"If an enriched air cylinder that has been prepared for oxygen service is accidentally filled from a conventional air source, it must be serviced and cleaned by someone qualified to service enriched air equipment before being exposed to more than 40% oxygen again." ~PADI

I've never been refused nitrox because I didn't have an 02 clean sticker. But then I've never used a dive shop that does partial pressure filling.

The definition in contention is "conventional air source". oca and hyp e is not conventional air. Yet many say if yo fill a nitrox tank with OCA you have to reclean to put nitrox in it again. that is BOGUS. Yet practiced.

Your first paragraph is correct you have to have a cylendar to qualify for the highest O2 contents it will be exposed to. Yet many see no difference between PP 30% and banked 30%. Psi admits that their 23.5% is based in the what if concept. what if you PP blended a 23.5% mix you would have pure 02 above 50psi and then top off with air if you used an empty tank to star with. the worst case scenereo point of view. You can have 23% at 3k but you cant have 23.5% greater than 50 psi with out O2 cleaning.

 

[NAM001]

That's nice, and the way I feel it should be. I've run into a few shops, though, that bank 32% and still require O2 cleaning...another of the 'their shop, their rules' situation if that's where I want/need to get fills.

I have 0one station in my area that will not put air in a nitrox stickered tank. no even OCA unless he treats it as a 20.9% nitrox fill and double charges for the nitrox mix process. another location will not fill a tank with a nitrox sticker without removing the valve to drain the tank then scraping the sticker and O2 vip sticker. You next fill with him requires a vip charge since you have no vip sticker on the tank.

Yes lots of variatons out there. So many wrong.

 

[tursiops]

Please supply a link to the above.

Those quotes are taken from the 2009 (current) PADI EANX manual, pages 8-12, but they are not quite the complete quotes. Here they are again, as in the manual:
Gas mixes with more than 40% oxygen require equipment (including cylinders) that has been cleaned to oxygen service specifications.

Because the cylinder valve and interior will be in contact with pure oxygen, if partial pressure blending with oxygen will be used, the cylinder must meet oxygen service standards, even if the final enriched air blend will have less than 40% oxygen. <some more stuff>The standard SCUBA cylinder doesn't meet these requirements.

If an enriched air cylinder that has been prepared for oxygen service is accidentally filled from a conventional air source, it must be serviced and cleaned by someone qualified to service enriched air equipment before being exposed to more than 40% oxygen again.

In addition, the instructor manual (p26) says:
d. To use air in an oxygen service rated enriched air cylinder, have it filled with oxygen compatible air by a qualified enriched air blender. The fill is treated as enriched air in all respects, including marking it as EANx21 — enriched air with 21 percent oxygen — analyzing the contents and completing all records.
e. Enriched air cylinders that are not oxygen service rated may be used for premixed enriched air blends with up to 40 percent oxygen only. They may be filled from standard air sources by a qualified enriched air blender (it will be labeled as EANx21), but should never have pure oxygen or enriched air with more than 40 percent oxygen put into them at any time.

This is alluded to on p11 of the student manual.

 

[NAM001]

Those quotes are taken from the 2009 (current) PADI EANX manual, pages 8-12, but they are not quite the complete quotes. Here they are again, as in the manual:
Gas mixes with more than 40% oxygen require equipment (including cylinders) that has been cleaned to oxygen service specifications.

Because the cylinder valve and interior will be in contact with pure oxygen, if partial pressure blending with oxygen will be used, the cylinder must meet oxygen service standards, even if the final enriched air blend will have less than 40% oxygen. <some more stuff>The standard SCUBA cylinder doesn't meet these requirements.

If an enriched air cylinder that has been prepared for oxygen service is accidentally filled from a conventional air source, it must be serviced and cleaned by someone qualified to service enriched air equipment before being exposed to more than 40% oxygen again.

In addition, the instructor manual (p26) says:
d. To use air in an oxygen service rated enriched air cylinder, have it filled with oxygen compatible air by a qualified enriched air blender. The fill is treated as enriched air in all respects, including marking it as EANx21 — enriched air with 21 percent oxygen — analyzing the contents and completing all records.
e. Enriched air cylinders that are not oxygen service rated may be used for premixed enriched air blends with up to 40 percent oxygen only. They may be filled from standard air sources by a qualified enriched air blender (it will be labeled as EANx21), but should never have pure oxygen or enriched air with more than 40 percent oxygen put into them at any time.

This is alluded to on p11 of the student manual.

I agree with the quote in application. That is the way I do it. However regs say otherwise. The part I do not understand is """The standard SCUBA cylinder doesn't meet these requirements."""" Is this another definition of perhaps standard. in that a scuba tank contains air.
The statement seams to imply that yo can put high O2 contents in it and not be covered by cleanliness requirements. I would say that once you start with EAN it is no longer a "standard" scuba tank. I n its application. Is it saying tat a standard scuba tank is assumed to not come in contact with elevated O2level exposure?? The other way I read this is that the scuba tank if filled >40% must be O2 clean """"That standard tank does not meet those requirements" and must be made O2 clean? The later makes the most sense.

 

[KevinNM]

what if you PP blended a 23.5% mix you would have pure 02 above 50psi and then top off with air if you used an empty tank to star with. the worst case scenereo point of view. You can have 23% at 3k but you cant have 23.5% greater than 50 psi with out O2 cleaning.

Why the pressure limit? The Apollo 1 fire didn't have 50 psi of 100%. You get massive changes in flammability just from the oxygen content.

 

[NAM001]

Why the pressure limit? The Apollo 1 fire didn't have 50 psi of 100%. You get massive changes in flammability just from the oxygen content.

That part I cant answer. a lot does not make sense and in my opinion is not based on any science I am aware of. It cant be because of fire and tank explosion. that is not real at that psi.

 

[BRT]

That part I cant answer. a lot does not make sense and in my opinion is not based on any science I am aware of. It cant be because of fire and tank explosion. that is not real at that psi.

I'm quite sure that higher partial pressures of 02 are more of a combustion risk. We run pure O2 through rubber hoses for welding at 40 psi and less with no issues.

 

[NAM001]

Those quotes are taken from the 2009 (current) PADI EANX manual, pages 8-12, but they are not quite the complete quotes. Here they are again, as in the manual:
Gas mixes with more than 40% oxygen require equipment (including cylinders) that has been cleaned to oxygen service specifications.

Because the cylinder valve and interior will be in contact with pure oxygen, if partial pressure blending with oxygen will be used, the cylinder must meet oxygen service standards, even if the final enriched air blend will have less than 40% oxygen. <some more stuff>The standard SCUBA cylinder doesn't meet these requirements.

If an enriched air cylinder that has been prepared for oxygen service is accidentally filled from a conventional air source, it must be serviced and cleaned by someone qualified to service enriched air equipment before being exposed to more than 40% oxygen again.

In addition, the instructor manual (p26) says:
d. To use air in an oxygen service rated enriched air cylinder, have it filled with oxygen compatible air by a qualified enriched air blender. The fill is treated as enriched air in all respects, including marking it as EANx21 — enriched air with 21 percent oxygen — analyzing the contents and completing all records.
e. Enriched air cylinders that are not oxygen service rated may be used for premixed enriched air blends with up to 40 percent oxygen only. They may be filled from standard air sources by a qualified enriched air blender (it will be labeled as EANx21), but should never have pure oxygen or enriched air with more than 40 percent oxygen put into them at any time.

This is alluded to on p11 of the student manual.

(d) follows the concept that fit is to have >40% in it it has to have OCA in it only to be enriched to any level. Use to be that the NITROX decal meant no air less than OCA and expected contents were greater than 40% nitrox only. 32% was a no-no 50% was ok
(e) Those guidelines follow <40 is air and >40 is O2

(e) according to PSI there is no such thing as an EAN cylinder that is not O2 cleaned unless <23.5% and < 50psi. Padi and other agencies are often an example PSI uses in their course. Their response is that when things go south PADI and others will pay the price for not following fed regs.

 

[NAM001]

I'm quite sure that higher partial pressures of 02 are more of a combustion risk. We run pure O2 through rubber hoses for welding at 40 psi and less with no issues.

I know,,,, I will look in my PSI book and it has a discussion regarding the 23.5 ill post it if I can find it. Higher the PPo2 the faster the corrosion. One reason for storing tanks with 50 psi or less over the winter.

 

[Scared Silly]

Tursiops thanks for supplying the reference to the 2009 (current) PADI EANX manual.

(e) according to PSI there is no such thing as an EAN cylinder that is not O2 cleaned unless <23.5% and < 50psi. Padi and other agencies are often an example PSI uses in their course. Their response is that when things go south PADI and others will pay the price for not following fed regs.

It is really CGA that says the above and then by reference gets incorporated into the Federal Regulations. But regardless I am surprised that PADI is saying that and has been for so long. Especially given their emphasis on standards and risk management.