Scuba Tanks & Nitrox

[FishDiver]

The point is that Nitrox is a manufactured product, and therefore taxable. It doesn't matter how you make it; the point is that the supplier is creating a new product. By contrast, an air fill goes on the books as service, which thus far they haven't chosen to tax.

And by the way, I think Monterey's tax rate of 8.25% is about the lowest in the state.

I will contribute to the thread hijack by noting that Dolphin Scuba in Sacto charges tax on air fills. Since the fills are only $3 I never thought to complain.

 

[SDAnderson]

My suggestion is take it to take it to a shop that really knows what they are talking about (at least to get a VIP) and pay for a VIP to detect any hydro carbons with light. IF they do, get them O2 cleaned and have them put an O2 clean sticker on it. If no visible hydrocarbons are present, an O2 clean would be rather redundant. I understand their reluctance if the shop that VIP'd the tank didn't check for hydrocarbons but hey, what can you do?

Many hydrocarbons (particularly synthetic lubricants commonly used in compressors) don't fluoresce under black light, so black light tests are not conclusive. Actually, there is no test or series of tests that will determine if a cylinder is oxygen clean or serviced. When in doubt, the only acceptable practice is to actually oxygen clean and service the cylinder and valve.

Almost any scuba gear (clean or not) is compatible with nitrox up to 40% O2 up to 2400 psi, including kit with Ti, buna or nylon components. At those levels, even a combination of crud, adiabatic compression, friction and particle impingement usually isn't enough of a fuel/ignition source to cause a problem. Increase the O2 or the pressure and things start to get wobbly, fast. There is almost no scuba equipment (clean or not) compatible with 100% at 3500 psi. At those levels, you're getting dangerously close to self-ignition on many common materials and any contamination or ignition source is a very serious threat.

So what does it mean when a manufacturer says their equipment is suitable for use with nitrox up to 40%? That depends on your perspective, I suppose. At one end of the scale they aren't saying much, at the other end of the scale they might be accused of trying to sucker ignorant consumers. Another possibility might be that they're terrified of blood-sucking lawyers and feel they have to hedge their bets. One thing you know for certain, they are NOT saying that the cylinder is suitable for use in 100% oxygen which is what partial pressure blending requires. Maybe they can be serviced for oxygen use, maybe not.

Caveat emptor.

 

[zaberman1]

Many hydrocarbons (particularly synthetic lubricants commonly used in compressors) don't fluoresce under black light, so black light tests are not conclusive. Actually, there is no test or series of tests that will determine if a cylinder is oxygen clean or serviced. When in doubt, the only acceptable practice is to actually oxygen clean and service the cylinder and valve.

Almost any scuba gear (clean or not) is compatible with nitrox up to 40% O2 up to 2400 psi, including kit with Ti, buna or nylon components. At those levels, even a combination of crud, adiabatic compression, friction and particle impingement usually isn't enough of a fuel/ignition source to cause a problem. Increase the O2 or the pressure and things start to get wobbly, fast. There is almost no scuba equipment (clean or not) compatible with 100% at 3500 psi. At those levels, you're getting dangerously close to self-ignition on many common materials and any contamination or ignition source is a very serious threat.

So what does it mean when a manufacturer says their equipment is suitable for use with nitrox up to 40%? That depends on your perspective, I suppose. At one end of the scale they aren't saying much, at the other end of the scale they might be accused of trying to sucker ignorant consumers. Another possibility might be that they're terrified of blood-sucking lawyers and feel they have to hedge their bets. One thing you know for certain, they are NOT saying that the cylinder is suitable for use in 100% oxygen which is what partial pressure blending requires. Maybe they can be serviced for oxygen use, maybe not.

Caveat emptor.

Though I agree with most of what you said, I do have some points. The O2 cleaning we as scuba professionals perform is an informal cleaning meant to remove visible hydrocarbons and some of the ones we do not see via O2 cleaning. Most facilities that O2 clean do not use distilled water for pre/post wash, they just use an O2 compatible wash and tumble. This is not a good process, but it does reveal that most shops do what is convenient. Consequently, we may actually be adding contaminants in there (not saying putting in more than we remove). To clarify what I mean by informal (the non-distilled water is not informal):

XS Scuba Luxfer Oxygen-Enriched and Oxygen Serivce FAQ

While black light tests may not be the BEST form of hydrocarbon detection (the light should be at the proper frequency, not the black light we get at the store), it is certainly the best one the industry has for detection (that I am familiar with...though NASA uses IR spectrophotometers sp?). It detects MOST hydrocarbons and I also do not accept that all hydrocarbons are removed from the informal O2 cleaning process. Of course, when in doubt, clean but a thorough inspection MAY rule out the absolute necessity to have it done every year (legally). It is currently not required to get a wash, for instance, every time you inspect the cylinder. My suggestion to the OP isn't wrong or dangerous given that he has a new tank from the factory but I agree, when in doubt, clean. The battle of oxygen clean/not clean/detection is ongoing and and inconclusive. Ie hoses, regulators, tanks, valves, o-rings, etc.

UV technology seems to work for other industries with greater exposure to O2 than we have and I do not see why it is unacceptable. Sure, it is not the litmus test for passing but is sufficient to demand a cleaning. GMCscuba, btw, has some good testing supplies and explanations... Maybe you can shed some light on it? No pun intended



Hydrocarbon contamination detection with UV blacklights

UV blacklight fluorescent inspection lamps for hydrocarbon contamination detection.

Ultrviolet Cylinder Inspection Lights

 

[SDAnderson]

Though I agree with most of what you said, I do have some points.

Maybe I didn't understand what you said...in your second post you said, "blacklight is not the litmus test for passing"...hydrocarbon inspection, yet wasn't that what you were advocating in your first post?

We're at risk of getting way off topic here but a couple of thoughts:

Yes, the oxygen cleaning protocols and standards used in scuba are less rigorous than NASA employs. Scuba differs from NASA in a couple of important ways: (a) we don't need NASA clean to be effective, and (b) we don't have the budget for NASA clean. It's worth adding that even NASA has a number of O2 service protocols designed to meet their requirements in specific situations. The scuba protocols may not be "perfect" (whatever that is) but they do an adequate job of meeting our needs, if they are followed.

Yes, some shops don't do a very good job of following the protocol and they certainly should but that's not relevant to the discussion. People will cut corners and fudge protocols but that doesn't mean its the smart thing or the right thing to do. We shouldn't be encouraging anyone to take a short-cut, either.

Global makes money selling blacklight equipment. Would you expect them to say it's largely ineffective? It's fine to use blacklight as a verification tool when cleaning - I do - but relying on it (and it alone) to determine if cleaning is needed is inadequate. You're PADI, TDI and PSI trained and all of those agencies agree on this point.

Some might consider this a reductio ad absurdum, I don't:

1. Compressor lubricant is the most common source of hydrocarbon contamination.
2. Many (most) compressors are using synthetic lubricants.
3. Many (most) synthetic lubricants used in compressors don't fluoresce under blacklight.
4. Blacklight is ineffective as a detection tool in many (most) situations.

Whether Worthington cylinders, fresh from the factory, can be considered O2 ready (as distinct from EAN ready) might be a debatable point. More to the point, however, is that OP didn't (a) understand the distinction between O2 ready and EAN ready and (b) didn't know the difference between Grade E air and hyperfiltered OCA. A nitrox diver should have learned all this during the class, now the cylinders are no longer fresh from the factory and he is looking at a pretty hefty bill for his ignorance.

The most important point, the one thing that will do the most to avoid problems like this in the future, is for divers to remember that millenia old axiom: caveat emptor. The vendor doesn't have to be lying or intentionally misleading you for you to get hurt if you don't know what you're doing.

 

[zaberman1]

Fair enough and thanks for the clarification, thats all I asked for . The first post I made may have been misleading and needed clarification which I hope was done both in my second post and by you (short responses during finals week is a necessity since I am addicted to SB). If this is way off topic, which I don't think it is, we can continue on PM or split into another thread....

That being said, I wasn't advocating cutting corners or short cuts, hence my referencing the protocol used for inspection and separating those practices from my definition. I hope at least that much was clear. Maybe I did not read the OP's question properly but my suggestion was for the new tank he purchased, nothing more.

Now to the hypothetical:

Are there any other methods (aside from the blacklight) to measure/test hydrocarbons? The byproducts we form may not all be visible by the black light but how does that compare to the contaminants potentially placed into the tank from cleaning (we can't all be perfect)? We are given a specific amount of acceptable hydrocarbons (less than 2.5 mi i think) but how can we determine whether or not a tank or inspection removes that much? In other words, how effective is the O2 clean process for non-visible hydrocarbons (although it is obviously safer than not cleaning)? These are questions which I would really like some technical answers to that I haven't found too much in agency literature. I wouldn't mind calling PSI/PCI or any of the other agencies if no one can come up with where to look...

 

[SDAnderson]

Now to the hypothetical:

Are there any other methods (aside from the blacklight) to measure/test hydrocarbons? The byproducts we form may not all be visible by the black light but how does that compare to the contaminants potentially placed into the tank from cleaning (we can't all be perfect)? We are given a specific amount of acceptable hydrocarbons (less than 2.5 mi i think) but how can we determine whether or not a tank or inspection removes that much? In other words, how effective is the O2 clean process for non-visible hydrocarbons (although it is obviously safer than not cleaning)? These are questions which I would really like some technical answers to that I haven't found too much in agency literature. I wouldn't mind calling PSI/PCI or any of the other agencies if no one can come up with where to look...

There are ways to pretty conclusively measure for hydrocarbon residue but they are too expensive to utilized in our arena. That's why following the cleaning protocol is so important. If you've followed all the steps carefully there shouldn't be any testing necessary, though the protocol does call for visual inspection in visible and ultraviolet along with smear and water break tests.

In the world of scuba, no amount of detectable hydrocarbons are acceptable when oxygen servicing equipment, if you find any when testing the standard is to start over again from scratch. NASA testing is more intense and they will allow some hydrocarbons in some instances.

How effective is the scuba oxygen cleaning protocol when measured against an absolute? I don't know the answer to that, the folks at PSI might be able to give you an answer.

Here is some extracted information from one NASA unit that might be of interest...

NASA Glenn Research Center Glenn Safety Manual
Chapter 5 - Oxygen
BMS Document GRC-M8300.001
Revision Date: 2/05

5.15 APPENDIX B - CLEANLINESS SPECIFICATION FOR GASEOUS/LIQUID OXYGEN SERVICE IN GLENN TEST FACILITY SYSTEMS

5.15.2 Requirements

Materials: All materials used shall have been previously determined to be compatible with oxygen and should be widely accepted throughout the aerospace industry. All materials shall be approved by the Glenn Assurance Management Office and/or the Area Safety Committee.

Lubricants: Liquid oxygen is a powerful oxidizing agent, so a petroleum-based lubricant must not be used. Special lubricants such as the fluorolubes or the perfluorocarbons, which have been tested and found suitable for oxygen service, may be used. All lubricants shall be approved by the Glenn Assurance Management Office and/or the Area Safety Committee.

Cleanliness: All component parts shall be free of burrs, chips, scale, slag, or foreign matter and shall be cleaned prior to assembly. Inspection for cleanliness shall consist of the following.

Visual inspection: Visible contamination shall require recleaning of the surface. Discoloration due to welding will be permitted, providing no scale or rust is associated with the discoloration. Visual inspection aided by an ultraviolet light source (3200 to 3800 angstrom wavelength) shall show no evidence of fluorescence from contamination.

White cloth inspection: Surfaces shall be rubbed in two directions with a clean, lint-free white cloth. Any evidence of oil, rust, stain, scale, or foreign matter will be cause for rejection. The cloth may be examined under natural or ultraviolet light. Use of ultraviolet light (3200 to 3800 angstrom wavelength) shall show no evidence of fluorescence from contamination.

Solvent rinse: Sufficient quantities of solvent rinse shall be used so as to yield 100-milliliters/square foot of internal surface area. The solvent rinse shall be performed by either sloshing or agitating the fluid around the inside surface of the components and straining it through a 5-micron, or finer, filter. Further instructions are found in ASTM MNL 36, January 2000.

CONTAMINATION LIMITS

a. Solid Particles
Particle size, microns Maximum number per 100-ml sample (Millipore test)
<100 = Unlimited
100 to 250 = 93
251 to 300 = 3
>300 = 0

b. Fibers
Fiber length (up to 25 um diameter), microns Maximum number of 100-ml sample (Millipore test)
0 to 500 = 20
501 to 1000 = 3
1001 to 1875 = >1875 None

c. Nonvolatile residue
Maximum residue, mg/square foot 1.0

d. Hydrocarbon limit
Ultraviolet Light = No fluorescence
Infrared spectrophotometer = 5 ppm hydrocarbon

e. Total solids and fibers
25 mg/square foot (maximum)

Cleaning: Cleaning shall consist of the typical cleaning, rinsing, and drying procedures used throughout the aerospace industry:

a. Cleaning shall consist of a thorough flushing of all surfaces with aqueous detergent solutions.
b. Rinsing shall consist of a thorough rinsing and flushing with de-mineralized water, followed by rinsing and flushing with isopropyl alcohol.
c. Drying shall consist of blowing dry with filtered gaseous nitrogen or oil-free air.​

Inspection: Inspection of cleaned components shall be performed by the solvent rinse method where possible. (This is generally done during the final cleaning stages and just prior to the drying operation.) The solvent shall be used at a rate of 100 milliliters per square foot of internal wetted surface area. (For all components having less than one square foot of internal wetted surface area, use 100 ml of solvent.) The solvent rinse shall be performed by either sloshing or agitating the fluid around the inside surface of the component to ensure dislodgment of particles. The rinse shall be poured through a filter sized to detect all particles greater than 100 microns. The assembled component, or any part thereof, shall be recleaned if it fails to pass the inspection(s).

 

[Guy Alcala]

Guy just posted it was $9 a fill if purchased on a fill card. Otherwise I believe it is $10. There is also tax since oxygen is a tangible product.

I personally do not spend much time in Monterery. Although I hope to spend more time there than usual over the Christmas New Years holidays this year.

Oops, I see you already caught the error. Never mind.

Guy

 

[GeorgeC]

.......There is almost no scuba equipment (clean or not) compatible with 100% at 3500 psi. At those levels, you're getting dangerously close to self-ignition on many common materials and any contamination or ignition source is a very serious threat.....

Reefraff,

What is the max pressure for 100% Oxygen when filling a bottle? Where can this rule be found?

Warm Regards,
George

 

[zaberman1]

I appreciate the response, and will research the topic more/call PSI for a firm answer and reference...

 

[GeorgeC]

Reefraff,

What is the max pressure for 100% Oxygen when filling a bottle? Where can this rule be found?

Warm Regards,
George

For pure oxygen, DOT mandates strict pressure limits: Gas pressure in an aluminum cylinder containing pure oxygen must never exceed 3,000 psi (even if the cylinder is stamped for a pressure above 3,000 psi).

From the XS Website FAQ's