The NOAA Diving Manual is an excellent reference book and belongs on the shelf of every serious diver. It's also copyright protected, which means quoting directly from it ("No part of this publication may be reproduced...) is a no-no. You can get your own copy directly from Best Publishing at
http://www.bestpub.com. It's worth the money. However, to paraphrase the manual:
Nitrox Diving (Chapter 15)
15.11.4 Cleaning for Oxygen Service
NOAA calls for any equipment that is exposed to a percentage of oxygen in excess of 40% at a pressure in excess of 200 psi to be oxygen cleaned, i.e., you don't need to clean your tanks if they are never filled with anything but premix not exceeding 40%. If you partial pressure blend or use hotter mixes, your tanks (and valves and regulators) must be specially cleaned and serviced. Basically, NOAA defers to other specifications for the details of oxygen cleaning and servicing, specifically mentioning CGA, ASTM, NFPA, NASA and US Navy standards. In a section of the NOAA manual called "Informal Oxygen Cleaning" the general process is reviewed, including the need to use special cleaning agents and techniques, and oxygen compatible lubricants and materials. The NOAA standard also calls for the technicians performing oxygen cleaning and servicing to receive special training.
Chapter 15.12.2: Identification of Nitrox Cylinders
Calls for a four-inch green band on a yellow background at least one-in wide with two-inch tall lettering that says "Nitrox" or "Enriched Air" or similar. Readers will notice that "Geezer Gas" and "Voodoo Gas" are not specifically mentioned but the presumption has to be that neither would be acceptable.
15.12.3 Cylinder Label for Oxygen Cleaning
NOAA has a specific label (or will accept MIL STD 1330) that must be used. The label states that the tank was cleaned and inspected in accordance with NOAA standards. There is a punch out indicating that the tank may be used for either (a) oxygen service or (b) premix nitrox up to 40% but not both. There is also a punch out for the date of the cleaning/inspection and a statement that the cylinder will require reinspection at 12 months or sooner if contaminated.
15.12.4 Cylinder Labeling
Each cylinder must be labeled with the fill date, cylinder pressure, oxygen percentage, maximum operating depth, the name or identification of the person completing the label, and the user's initials verifying that it was analyzed.
Mixed-Gas and Oxygen Diving (Chapter 16)
16.8 Cylinder Identification and Labeling
The section discusses the requirements for a contents label, essentially as discussed in Chapter 15. It adds that abbreviations for mixes should not be used, i.e., don't use the common abbreviation 18/50 but, instead, write out the mix - Oxygen 18%, Helium 50%, Nitrogen 32%.
It says that there is a clear convention for nitrox labeling and refers to Chapter 15 for details. It also mentions that oxygen cylinders are usually white or green with the word OXYGEN stenciled on the cylinder. Optionally, 20 may also be stenciled near the bottom of cylinders containing 100% O2. The section also states that there is not a standardized labeling or color coding system for trimix or heliox cylinders but it recommends that the MOD be marked in 2-3 inch letters horizontally near the bottom of the cylinder.
It's important to remember that NOAA rules apply only to NOAA operations - they aren't law and, if you aren't diving on a NOAA project, you are free to take or leave them. For the most part, they are good standards but they tend to run a bit behind the times - they were written in the days when Nitrox was considered to be pretty much out there and trimix was freaky-scary stuff. As more and more sport divers use these gases it becomes important to iron out some of the inconsistencies and eliminate some of the bugaboo stuff. Personally, though I clean to CGA and ANDI standards, I don't use the nitrox bumper sticker on my tanks and mark the MOD vertically near the shoulder of the tank (not the bottom) on my deco and stage bottles - all my other bottles only have the MOD marked on the contents label.
Hope this helps.
(assuming you are qualified)
