Regs & Nitrox

[Diver806]

I can agree that it is difficult to determine if a dive facility has OCA (oxygen clean air). The facility where I dive has their air results posted above the fill station for all customers to see. To "assume" you can get OCA air at a lot of places would be wrong. It depends on how they fills tanks (banked air or membrane system). A facility that partial pressure blends will have to have OCA air coming out of their fill station becuase they will have to add air to the tank that has O2 in it.

Chris

 

[Ron Brandt]

What the hell is O2 clean air ? Does this mean I loose my Tri-mix blender credential ? My regs are the same for everything. 21%,40%,50%,100% o2

Ron

 

[mermom]

So are you telling Grendel that you should have 2 different regulators if you decide to use Nitrox? Or can you use the same reg, such as the Genesis2000, which is Nitrox compatible up to 40%, for both?

 

[Iguana Don]

Mermom,

You can use the same reg for Nitrox as you do for "straight" air. No need to purchase a second reg.

ID

 

[The Chairman]

Most (if not all) regulators should be fine for use with NitrOx up to %40. HOWEVER, the Enriched Air manuals I have read leave the final say for NitrOx suitablility to the individual manufacturers. Check with your manufacturer or their literature to be sure.

As for air, I always get my Oxygen suitable tanks filled from my local NitrOx blender. Even if it's just plain ol' air, they know enough to use the same air that they would have used to dilute the Oxygen anyway.

Most people tend to worry about an explosion from the oil residue associated with "dirty air". Actually, there is usually not enough oil to explode. Still, it will oxidize (burn) when pure oxygen is introduced into it, and the subsequent byproducts will poison the final mixture.

 

[Ron Brandt]

Let the manufacturer make the call ? Well, the manufacturers are in business. They want to make you think you need to spend more money. I personally use Scuba Pro and Oceanic regs with no modification on all blends up to 100% O2. Note: I am a CERTIFIED blender tech. Yup,the guy that 02 cleans your tank and puts the 02(and he.) in.

Yes , with my 30 min of labour the dive shop can charge you the diver BIG MONEY for this !

Ron

 

[blacknet]

Guys guys guys,

Lets make this simple.

Nitrox less than 40% o2 (in the civilian world) you do NOT need to o2 clean your regs. You *DO* need to o2 clean your tanks IF it is a partial pressure fill. IF it is a 'premix' (membrane) fill you do *NOT* need to o2 clean the tank.

Nitrox greater than 41% o2 you DO need to o2 clean everything (fire hazard)

Call the shop(s) you will be filling your nitrox tanks with and see what setup they use. You may just be able to get away with slaping a sticker on any tank that states "dna nitrox" or "nitrox only"

I know that PSI has 3 forms of inspection stickers "suitable for air service" "suitable for enriched air service" and "suitable for oxygen service", air service is a no brainer, 'enriched air service' means you can get a partial pressure fill to 40% (technicaly above NNII to 40% is a gray area) if the tank is o2 clean or a regular tank if using a membrane (premix) system, suitable for oxygen service means it's full blown o2 clean and you can ONLY use equipment that's o2 clean and you best be very anal about filling the tank. If you are going the later route then make log entries in your log book as to who cleaned the tank and when, who filled the tank, what %, when, where, how and have them initial it.

The 'o2 cleaning' process is simply removing all the nasty stuff from the tank and reg, removing all the silicon grease and replace it with a more o2 friendly grease that doesn't have the nasty fire hazard associated with it like silicon does The o-rings are replaced, everything is cleaned, tank is inspected for vapor/carbons/nasties and everything is repacked. It's basicaly an overhaul but with strict standards and high $ grease.

FYI o2 service stations that does partial pressure fills typicaly produces CLEANER gas than the normal compressed air stations does. They have to be because of the fire hazard (as they watch hydrocarbons, vapors and the like)

I recently purchased some stage bottles and intend to run 100% o2 thru one of them (but not at this current time) I had them o2 cleaned and will ONLY use partial pressure fills on them.

Ed

 

[rainreg]

Hello I have been watching this thread to see where it would go and before people get to far off track I wanted to enlighten you all on this subject.

This so called 40% rule is no real rule what so ever, the number cannot be substantiated with any official test data or reports at all. The real deal is anything above 25% should be cleaned to 100% o2 standards, There are numerous tests and data to support this and they were conducted by White Sands Test Facility. This is a Federal / Government run Facility and has been doing testing for (NASA, The Department of Defense and the like) since the 60's. Your tax dollars have been paying for the tests and the reports. The information is available from DTIC (Defense Technical Information Center) http://www.dtic.mil/ or you can get the info from me I have copies in my own Technical Library. These are Official Reports and have proof to back it up, As far as the DOD (Department of Defense) They us a procedure for O2 Cleaning based on an instruction that is referred to as the Mil-std- 1330D, this instruction gives a specific process to follow to complete O2 Cleaning of Components and the like. It has additional substantiated documentation by ASTM G 63 (Standard Guide for Evaluating Nonmetallic Materials for Oxygen Service) and ASTM G 94 (Standard Guide for evaluating metals for Oxygen Service. There are also other documents such as the Note: "Autoignition Temperature of selected Polymers at elevated Oxygen pressure and their Heat of Combustion” by Fu-Yu Hshieh, Joel M. Stolzfus and Harold D. Beeson. This document also refers to ASTM G 72.

By now you can see that there is really Substantial documentation to disprove the 40% rule in which the DOD and Federal Government do not recognize, They only recognize the 25% rule stated above.

I Retire form the U.S. Navy on 31 August (I have been a Diver for them almost my entire 20+ years of service. I am currently a Saturation Diver and I have worked with this particular Standard for years.... I am a qualified O2 Clean Room Technician as well as an O2 Clean room Operator. I have re-written the 1330D in civilian terms and forwarded it to White Sands, and NASA for approval. This abides by the 25% rule and I will be providing a training class As soon as I receive Final Approval from NASA. No other Blending, Cleaning or other civilian course has this approval and well I can prove It can be cost effective to build your own clean room and perform the work and charge less than what is being charged now. I will keep you posted through Scubasource.

OK After all of that I hope this may change your outlook on the so-called o2 cleaning you have been performing / paying for.

Any more questions on this subject feel free to add.

Michael Rainone
U.S. Navy Saturation Diver (Almost retired)

 

[blacknet]

Hello,

Yes I read the 25% rule in the manual but most agencies endorses the 40% rule (think one agency uses 25% and they get bashed for it last I checked). So the actual question now is WHERE did the 40% rule come from that these agencies uses? I talked to iantd and he told me 40% for o2 cleaning (even mentioned goverment standards of 25%) cause that was one of my concerns, conflicting standards.

IANTD states -> "NOTE: Tanks and regulators used with gases containing oxygen concentrations greater than 40% must be O2 service rated (example: partial pressure blending requires oxygen service rated tanks)."

GUE states -> (cylinder should be oxygen clean for mixtures over 40%)

DNA states this -> http://www.dnax.com/dnax.html -> "Existing oxygen mixing and blending setups employ high oxygen concentrations that require oxygen clean (free of contamination) equipment. Our denitrogenated air never exceeds 40% oxygen and does not require O2 cleaning. "

ANDI states the 40% is a myth -> http://www.andihq.com/ANDIHQ/news.htm

The problem comes into play when I goto a membrane system with my o2 clean unit and they dirty my o2 clean units by filling them.

Ed

 

[blacknet]

Hello,

Just found this link by Dick Rutkowski where he states the source of the 40% (have not yet verified these sources he quotes)

http://www.dnax.com/o2myths.html

Ed